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fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.2 UE IP Address Management | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.2.1 General | The UE IP address management includes allocation and release of the UE IP address as well as renewal of the allocated IP address, where applicable.
The UE shall perform the association of the application to a new PDU Session described in clause 6.1.2.2.1 of TS 23.503 [45], with the following considerations:
- If there is a matching URSP rule, except the URSP rule with the "match all" Traffic descriptor, or a matching UE Local Configuration containing a PDU Session Type of "IPv4", "IPv6" or "IPv4v6", then the UE shall set the requested PDU Session Type to the PDU Session Type contained in the matching URSP rule or in the matching UE Local Configuration, if this PDU Session Type is supported by the UE's IP stack capabilities Detailed operation is described in TS 24.526 [110].
- Otherwise, if a URSP Rule with the "match all" Traffic descriptor exists, the UE shall set the requested PDU Session Type to the PDU Session Type contained in the "match all" URSP Rule, if this PDU Session Type is supported by the UE's IP stack capabilities. Detailed operation is described in TS 24.526 [110].
- Otherwise, the UE shall set the requested PDU Session Type during the PDU Session Establishment procedure based on its IP stack capabilities as follows:
- A UE which supports IPv6 and IPv4 shall set the requested PDU Session Type "IPv4v6".
- A UE which supports only IPv4 shall request for PDU Session Type "IPv4".
- A UE which supports only IPv6 shall request for PDU Session Type "IPv6".
- When the IP version capability of the UE is unknown in the UE (as in the case when the MT and TE are separated and the capability of the TE is not known in the MT), the UE shall request for PDU Session Type "IPv4v6".
The SMF selects PDU Session Type of the PDU Session as follows:
- If the SMF receives a request with PDU Session Type set to "IPv4v6", the SMF selects either PDU Session Type "IPv4" or "IPv6" or "IPv4v6" based on DNN configuration, subscription data and operator policies.
- If the SMF receives a request for PDU Session Type "IPv4" or "IPv6" and the requested IP version is supported by the DNN the SMF selects the requested PDU Session type.
In its answer to the UE, the SMF may indicate the PDU Session Types not allowed for the combination of (DNN, S-NNSAI). In this case, the UE shall not request another PDU Session to the same (DNN, S-NNSAI) for PDU Session Types indicated as not allowed by the network. In the case that the initial PDU Session was established with a PDU Session Type and the UE needs another single IP version PDU Session Type, the UE may initiate another PDU Session Establishment procedure to this (DNN, S-NNSAI) in order to activate a second PDU session with that PDU Session Type.
An SMF shall ensure that the IP address management procedure is based on the selected PDU Session Type. If IPv4 PDU Session Type is selected, an IPv4 address is allocated to the UE. Similarly, if IPv6 PDU Session type is selected, an IPv6 prefix is allocated. If IPv4v6 PDU Session Type is selected, both an IPv4 address and an IPv6 prefix are allocated. For Roaming case, the SMF in this clause refers to the SMF controlling the UPF(s) acting as PDU Session Anchor. i.e. H-SMF in home routed case and V-SMF in local breakout case. For home routed case, V-SMF forwards the PDU Session Type requested by UE to H-SMF without interpreting it. V-SMF sends back to UE the PDU Session Type selected by H-SMF. The SMF shall process the UE IP address management related messages, maintain the corresponding state information and provide the response messages to the UE.
The 5GC and UE support the following mechanisms:
a. During PDU Session Establishment procedure, the SMF sends the IP address to the UE via SM NAS signalling. The IPv4 address allocation and/or IPv4 parameter configuration via DHCPv4 (according to RFC 2131 [9]) can also be used once PDU Session is established.
b. /64 IPv6 prefix allocation shall be supported via IPv6 Stateless Auto-configuration according to RFC 4862 [10], if IPv6 is supported. The details of Stateless IPv6 Address Autoconfiguration are described in clause 5.8.2.2.3. IPv6 parameter configuration via Stateless DHCPv6 (according to RFC 8415 [182]) may also be supported. IPv6 Prefix Delegation using DHCPv6 may be supported for allocating additional IPv6 prefixes for a PDU Session. The details of Prefix Delegation are described in clause 5.8.2.2.4.
For scenarios with RG connecting to 5GC, additional features for IPv6 address allocation and IPv6 prefix delegation are supported, as described in TS 23.316 [84].
To allocate the IP address via DHCPv4, the UE may indicate to the network within the Protocol Configuration Options that the UE requests to obtain the IPv4 address with DHCPv4, or obtain the IP address during the PDU Session Establishment procedure. This implies the following behaviour both for static and dynamic address allocation:
- The UE may indicate that it requests to obtain an IPv4 address as part of the PDU Session Establishment procedure. In such a case, the UE relies on the 5GC network to provide IPv4 address to the UE as part of the PDU Session Establishment procedure.
- The UE may indicate that it requests to obtain the IPv4 address after the PDU Session Establishment procedure by DHCPv4. That is, when the 5GC network supports DHCPv4 and allows that, it does not provide the IPv4 address for the UE as part of the PDU Session Establishment procedure. The network may respond to the UE by setting the allocated IPv4 Address to 0.0.0.0. After the PDU Session Establishment procedure is completed, the UE uses the connectivity with the 5GC and initiates the IPv4 address allocation on its own using DHCPv4. However, if the 5GC network provides IPv4 address to the UE as part of the PDU Session Establishment procedure, the UE should accept the IPv4 address indicated in the PDU Session Establishment procedure.
- If the UE sends no IP Address Allocation request, the SMF determines whether DHCPv4 is used between the UE and the SMF or not, based on per DNN configuration.
If dynamic policy provisioning is deployed and the PCF was not informed of the IPv4 address at PDU Session Establishment procedure, the SMF shall inform the PCF about an allocated IPv4 address. If the IPv4 address is released, the SMF shall inform the PCF about the de-allocation of an IPv4 address.
In order to support DHCP based IP address configuration, the SMF shall act as the DHCP server towards the UE. The PDU Session Anchor UPF does not have any related DHCP functionality. The SMF instructs the PDU Session Anchor UPF serving the PDU Session to forward DHCP packets between the UE and the SMF over the user plane.
When DHCP is used for external data network assigned addressing and parameter configuration, the SMF shall act as the DHCP client towards the external DHCP server. The UPF does not have any related DHCP functionality. In the case of DHCP server on the external data network, the SMF instructs a UPF with N6 connectivity to forward DHCP packets between the UE and the SMF and the external DHCP server over the user plane.
The 5GC may also support the allocation of a static IPv4 address and/or a static IPv6 prefix based on subscription information in the UDM or based on the configuration on a per-subscriber, per-DNN basis and per-S-NSSAI. 5GC may support the provisioning of a static IPv4 address and/or a static IPv6 prefix in the subscription information in the UDM based on NEF Parameter Provision service as described in clause 4.15.6.5 of TS 23.502 [3].
If the static IP address/prefix is stored in the UDM, during PDU Session Establishment procedure, the SMF retrieves this static IP address/prefix from the UDM. If the static IP address/prefix is not stored in the UDM subscription record, it may be configured on a per-subscriber, per-DNN and per-S-NSSAI basis in the DHCP/DN-AAA server and the SMF retrieves the IP address/prefix for the UE from the DHCP/DN-AAA server. This IP address/prefix is delivered to the UE in the same way as a dynamic IP address/prefix. It is transparent to the UE whether the PLMN or the external data network allocates the IP address and whether the IP address is static or dynamic. If the SMF is notified by UDM that the subscription data has changed and SMF detects that the static IP address/prefix in the subscription data is added, removed or modified, the SMF may trigger a release of the PDU Session and includes a cause value indicating that a PDU Session re-establishment is requested, as described in clause 4.3.4 of TS 23.502 [3].
For IPv4 or IPv6 or IPv4v6 PDU Session Type, during PDU Session Establishment procedure, the SMF may receive a Subscriber's IP Index from the UDM. If the UE IP address/prefix was not already allocated and provided to PCF when SMF initiates the SM policy association, the SMF may receive a Subscribers IP Index from the PCF. If the SMF received a Subscriber's IP index from both UDM and PCF, the SMF shall apply the Subscriber's IP Index received from the PCF. The SMF may use the Subscriber's IP Index to assist in selecting how the IP address is to be allocated when multiple allocation methods, or multiple instances of the same method are supported. In the case of Home Routed roaming, the H-SMF may receive the IP index from the H-PCF.
NOTE: The IP Index can e.g. be used to select between different IP pools, including between IP pools with overlapping private address range. To support deployments with overlapping private IPv4 address, the IP domain corresponding to IP index can also be provided from UDM to SMF as part of the subscription data and then provided to PCF.
When Static IP addresses for a PDU session are not used, the actual allocation of the IP Address(es) for a PDU Session may use any of the following mechanisms:
- The SMF allocates the IP address from a pool that corresponds to the PDU Session Anchor (UPF) that has been selected
- The UE IP address is obtained from the UPF. In that case the SMF shall interact with the UPF via N4 procedures to obtain a suitable IP address. The SMF provides the UPF with the necessary information allowing the UPF to derive the proper IP address (e.g. the network instance).
- In the case that the UE IP address is obtained from the external data network, additionally, the SMF shall also send the allocation, renewal and release related request messages to the external data network, i.e. DHCP/DN-AAA server and maintain the corresponding state information. The IP address allocation request sent to DHCP/DN-AAA server may include the IP address pool ID to identify which range of IP address is to be allocated. In this case the SMF is provisioned with separate IP address pool ID(s) and the mapping between IP address pool ID and UPF Id, DNN, S-NSSAI, IP version. The provision is done by OAM or during the N4 Association Setup procedure.
A given IP address pool is controlled by a unique entity (either the SMF or the UPF or an external server). The IP address managed by the UPF can be partitioned into multiple IP address pool partition(s), i.e. associated with multiple IP address pool ID(s).
When the SMF is configured to obtain UE IP addresses from the UPF, the SMF may select a UPF based upon support of this feature. The SMF determines whether the UPF supports this feature via NRF or via N4 capability negotiation during N4 Association Setup. If no appropriate UPF support the feature, the SMF may allocate UE IP addresses, if configured to do so. Based on the operator policy, the UPF, e.g. for scenario described in Annex U, when allocating a UE IP address, may provide the SMF with DNS server information (and optionally DNS security information) corresponding to the target network instance, if it is locally configured with this information.
The IP address/prefix is released by the SMF (e.g. upon release of the PDU Session), likewise the UPF considers that any IP address it has allocated within a N4 session are released when this N4 session is released.
UPF may use NAT between the UE and the Data Network and thus the 5GC allocated (private) UE IP address may not be visible on the N6 reference point. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.2.2 Routing rules configuration | When the UE has an IPv6 multi-homed PDU Session the UE selects the source IPv6 prefix according to IPv6 multi-homed routing rules pre-configured in the UE or received from network. IPv6 multi-homed routing rules received from the network have a higher priority than IPv6 multi-homed routing rules pre-configured in the UE
The SMF can generate the IPv6 multi-homed routing rules for a UE based on local configuration or dynamic PCC rules received from the PCF as defined in TS 23.503 [45]. If dynamic PCC is deployed, the SMF generates the IPv6 multi-home routing rules for a source IPv6 prefix based on the SDF Templates of those PCC rules which contain the DNAI corresponding to the newly assigned IPv6 prefix. The SMF can send IPv6 multi-homed routing rules to the UE to influence the source IPv6 prefix selection in IPv6 Router Advertisement (RA) messages according to RFC 4191 [8] at any time during the lifetime of the IPv6 multi-homed PDU Session. Such messages are sent via the UPF.
NOTE: For multiple IPv4 PDU Session and multiple IPv6 PDU Session cases, routing rule based PDU Session selection is not specified in this Release of the specification. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.2.3 The procedure of Stateless IPv6 Address Autoconfiguration | If Stateless IPv6 Address Autoconfiguration is used for IPv6 address allocation to the UE, after PDU Session Establishment the UE may send a Router Solicitation message to the SMF to solicit a Router Advertisement message. The SMF sends a Router Advertisement message (solicited or unsolicited) to the UE. The Router Advertisement messages shall contain the IPv6 prefix.
After the UE has received the Router Advertisement message, it constructs a full IPv6 address via IPv6 Stateless Address Autoconfiguration in accordance with RFC 4862 [10]. To ensure that the link-local address generated by the UE does not collide with the link-local address of the UPF and the SMF, the SMF shall provide an interface identifier (see RFC 4862 [10]) to the UE and the UE shall use this interface identifier to configure its link-local address. For Stateless Address Autoconfiguration however, the UE can choose any interface identifier to generate IPv6 addresses, other than link-local, without involving the network. However, the UE shall not use any identifiers defined in TS 23.003 [19] as the basis for generating the interface identifier. For privacy, the UE may change the interface identifier used to generate full IPv6 address, as defined in TS 23.221 [23] without involving the network. Any prefix that the SMF advertises to the UE is globally unique. The SMF shall also record the relationship between the UE's identity (SUPI) and the allocated IPv6 prefix. Because any prefix that the SMF advertises to the UE is globally unique, there is no need for the UE to perform Duplicate Address Detection for any IPv6 address configured from the allocated IPv6 prefix. Even if the UE does not need to use Neighbor Solicitation messages for Duplicate Address Detection, the UE may, for example, use them to perform Neighbor Unreachability Detection towards the SMF, as defined in RFC 4861 [54]. Therefore, the SMF shall respond with a Neighbor Advertisement upon receiving a Neighbor Solicitation message from the UE.
In IPv6 multi-homing PDU session, SMF shall not allocate an interface identifier when a new IPv6 prefix allocated corresponding to the new PDU Session Anchor.
The above IPv6 related messages (e.g. Router Solicitation, Router Advertisement, Neighbor Solicitation, Neighbor Advertisement) are transferred between the SMF and UE via the UPF(s). If the Control Plane CIoT 5GS Optimisation is enabled for a PDU session, the above IPv6 related messages are transferred between the SMF and UE via the AMF after PDU Session Establishment, see clauses 4.3.2.2.1 and 4.3.2.2.2 of TS 23.502 [3], using the Mobile Terminated Data Transport in Control Plane CIoT 5GS Optimisation procedures. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.2.4 IPv6 Prefix Delegation via DHCPv6 | Optionally, a single network prefix shorter than the default /64 prefix may be assigned to a PDU Session. In this case, the /64 default prefix used for IPv6 stateless autoconfiguration will be allocated from this network prefix; the remaining address space from the network prefix can be delegated to the PDU Session using prefix delegation after the PDU Session establishment and IPv6 prefix allocation via IPv6 stateless address autoconfiguration as defined in clause 5.8.2.2.3.
Depending on configuration, the SMF may obtain the prefix from a locally provisioned pool, from the PSA UPF or from the external DN.
The address space provided is maintained as an IPv6 address space pool available to the PDU Session for DHCPv6 IPv6 prefix requests with the exclusion of the IPv6 prefix that is allocated to the PDU Session during PDU Session establishment as defined in clause 5.8.2.2.3. The total IPv6 address space available for the PDU Session (UE PDU Session prefix and UE PDU Session IPv6 address space pool) shall be possible to aggregate into one IPv6 prefix that will represent all IPv6 addresses that the UE may use.
If the UE had indicated that it supports prefix exclusion and the prefix to be delegated to the UE includes the /64 prefix that was allocated to the PDU Session, the SMF shall utilise the prefix exclusion feature as specified for DHCPv6 Prefix Delegation in IETF RFC 6603 [162].
NOTE: Support of the IPv6 prefix delegation in the SMF is assumed to be ensured by the operator e.g. by configuring specific DNN/S-NSSAI for PDU Sessions that are used by UEs that utilize IPv6 prefix delegation.
The UE uses DHCPv6 to request additional IPv6 prefixes (i.e. prefixes in addition to the default prefix) from the SMF after completing stateless IPv6 address autoconfiguration procedures. The UE acts as a "Requesting Router" as described in IETF RFC 8415 [163] and inserts one or more IA_PD option(s) into a DHCPv6 Solicit message sent from the UE to the SMF via the user plane and the UPF. The SMF acts as the DHCP server and fulfils the role of a "Delegating Router" according to IETF RFC 8415 [163]. The UE optionally includes the RAPID_COMMIT option in the DHCPv6 Solicit message to trigger two-message DHCPv6 procedure instead of the four-message DHCPv6 procedure. The UE shall include OPTION_PD_EXCLUDE option code in an OPTION_ORO option to indicate support for prefix exclusion. In response to the DHCPv6 Solicit message, the UE receives a DHCPv6 Reply message with one or more IA_PD prefix(es) for every IA_PD option that it sent in the DHCPv6 Solicit message. The SMF delegates a prefix excluding the default prefix with help of OPTION_PD_EXCLUDE. Prefix exclusion procedures shall follow IETF RFC 6603 [162].
For scenarios with RG connecting to 5GC, additional feature for IPv6 Prefix Delegation via DHCPv6 is defined in TS 23.316 [84]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.3 Management of CN Tunnel Info | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.3.1 General | CN Tunnel Info is the Core Network address of a N3/N9 tunnel corresponding to the PDU Session. It comprises the TEID and the IP address which is used by the UPF on the N3/N9 tunnel for the PDU Session.
The CN Tunnel Info allocation and release is performed by the UPF. The SMF shall indicate to the UPF when the UPF is required to allocate/release CN Tunnel Info. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.3.2 Void | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.3.3 Management of CN Tunnel Info in the UPF | The UPF shall manage the CN Tunnel Info space. When a new CN Tunnel Info is needed, the SMF shall request over N4 the UPF to allocate CN Tunnel Info for the applicable N3/N9 reference point. In response, the UPF provides CN Tunnel Info to the SMF. In the case of PDU Session Release or a UPF is removed from the user plane path of an existing PDU Session, the SMF shall request UPF to release CN Tunnel Info for the PDU Session. If the corresponding N4 Session is released the UPF releases the associated CN Tunnel Info. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.4 Traffic Detection | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.4.1 General | This clause describes the detection process at the UPF that identifies the packets belonging to a session, or a service data flow.
The SMF is responsible for instructing the UP function about how to detect user data traffic belonging to a Packet Detection Rule (PDR). The other parameters provided within a PDR describe how the UP function shall treat a packet that matches the detection information. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.4.2 Traffic Detection Information | The SMF controls the traffic detection at the UP function by providing detection information for every PDR.
For IPv4 or IPv6 or IPv4v6 PDU Session type, detection information is a combination of:
- CN tunnel info.
- Network instance.
- QFI.
- IP Packet Filter Set as defined in clause 5.7.6.2.
- Application Identifier: The Application Identifier is an index to a set of application detection rules configured in UPF.
- FQDN Filter for DNS Query message.
For Ethernet PDU Session type, detection information is a combination of:
- CN tunnel info.
- Network instance.
- QFI.
- Ethernet Packet Filter Set as defined in clause 5.7.6.3.
In this Release of the specification for Unstructured PDU Session Type, the UPF does not perform-QoS Flow level traffic detection for QoS enforcement.
Traffic detection information sent by the SMF to the UPF for a PDU Session may be associated with Network instance for detection and routing of traffic over N6. In the case of IP PDU Session Type, Network Instances can, e.g. be used by the UPF for traffic detection and routing in the case of different IP domains or overlapping IP addresses. In the case of Ethernet PDU Session Type, different Network Instances can e.g. be configured in the UPF with different ways to handle the association between N6 and the PDU Sessions.
When the DL traffic is end-to-end encrypted, the UPF may identify the media related information using On-Path N6 signalling as described in clause 5.37.9 |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.5 Control of User Plane Forwarding | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.5.1 General | The SMF controls user-plane packet forwarding for traffic detected by a PDR by providing a FAR with instructions to the UPF, including:
- Forwarding operation information;
- Forwarding target information.
The details of the forwarding target and operation will depend on the scenario and is described below. The following forwarding functionality is required by the UPF:
- Apply N3 /N9 tunnel related handling, i.e. encapsulation.
- Forward the traffic to/from the SMF, e.g. as described in Table 5.8.2.5.2-1.
- Forward the SM PDU DN Request Container from SMF to DN-AAA server
- Forward the traffic according to locally configured policy for traffic steering.
- Forward the traffic according to N4 rules of a 5G VN group for 5G VN group communication.
- Forward the traffic to/from the EASDF.
Data forwarding between the SMF and UPF is transmitted on the user plane tunnel established on N4 interface, defined in TS 29.244 [65]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.5.2 Data forwarding between the SMF and UPF | Scenarios for data forwarding between the SMF and UPF are defined as below:
Table 5.8.2.5.2-1: Scenarios for data forwarding between the SMF and UPF
Scenario description
Data forwarding direction
1
Forwarding of user-plane packets between the UE and the SMF e.g. DHCP signalling.
UPF to SMF
SMF to UPF
2
Forwarding of packets between the SMF and the external DN e.g. with DN-AAA server
UPF to SMF
SMF to UPF
3
Forwarding of packets subject to buffering in the SMF.
UPF to SMF
SMF to UPF
4
Forwarding of End Marker Packets constructed by the SMF to a downstream node.
SMF to UPF
5
Forwarding of user data using Control Plane CIoT 5GS Optimisation
UPF to SMF
SMF to UPF |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.5.3 Support of Ethernet PDU Session type | When configuring an UPF acting as PSA for an Ethernet PDU Session Type, the SMF may instruct the UPF to route the traffic based on detected MAC addresses as follows.
- The UPF learns the MAC address(es) connected via N6 based on the source MAC addresses of the DL traffic received on a N6 Network Instance.
- The UPF learns the MAC address(es) of UE(s) and devices connected behind, if any, based on the source MAC address contained within the UL traffic received on a PDU Session (N3/N9 interface).
- The UPF forwards DL unicast traffic (with a known destination address) on a PDU Session determined based on the source MAC address(es) used by the UE for the UL traffic.
- The UPF forwards UL unicast traffic (with a known destination address) on a port (PDU Session or N6 interface) determined based on the source MAC address(es) learned beforehand.
- In the case of multicast and broadcast traffic (if the destination MAC address is a broadcast or multicast address):
- for DL traffic received by UPF on a N6 Network Instance the UPF should forward the traffic to every DL PDU Session (corresponding to any N4 Session) associated with this Network Instance
- for uplink traffic received by UPF over a PDU session on a N3/N9 interface, the UPF should forward the traffic to the N6 interface and downlink to every PDU session (except toward the one of the incoming traffic) associated with the same N6 Network Instance
- for uplink and downlink unicast traffic received by UPF, if the destination MAC has not been learnt, the UPF should forward the traffic to every PDU session associated with the same N6 Network Instance and towards the N6 interface. In any case the traffic is not replicated on the PDU Session or the N6 interface of the incoming traffic.
NOTE 1: The UPF can consider a PDU Session or a N6 interface to be active or inactive in order to avoid forwarding loops. User data traffic is not sent on inactive PDU sessions or inactive N6 interface. This release of the specification does not further specify how the UPF determines whether a PDU Session or N6 interface is considered active or inactive.
NOTE 2: This release of the specification supports only a single N6 interface in a UPF associated with the N6 Network Instance.
- if the traffic is received with a VLAN ID, the above criteria apply only towards the N6 interface or PDU session matching the same VLAN ID, unless the UPF is instructed to remove the VLAN ID in the incoming traffic.
NOTE 3: This release of the specification supports Independent VLAN Learning (IVL) and does not support Shared VLAN Learning (SVL), as described in IEEE Std 802.1Q [98].
- if the destination MAC address of traffic refers to the same N6 interface or PDU session on which the traffic has been received, the frame shall be dropped.
In order to handle scenarios where a device behind a UE is moved from a source UE to a target UE, a MAC address is considered as no longer associated with a UPF interface (source UE's PDU session) when the MAC address has not been detected as Source MAC address in UL traffic for a pre-defined period of time or the MAC address has been detected under a different interface (target UE's PDU Session or N6).
NOTE 4: The UPF/NW-TT may also be provided with static filtering entries as described in clause 5.28.3. How the UPF uses the static filtering entry to achieve forwarding of Ethernet frames to one or more egress ports is up to UPF implementation. The externally observable behaviour of 5GS Bridge needs to comply with IEEE Std 802.1Q [98].
For ARP/IPv6 Neighbour Solicitation traffic, a SMF's request to respond to ARP/IPv6 Neighbour Solicitation based on local cache information or to redirect such traffic from the UPF to the SMF overrules the traffic forwarding rules described above.
NOTE 5: Local policies in UPF associated with the Network Instance can prevent local traffic switching in the UPF between PDU Sessions either for unicast traffic only or for any traffic. In the case where UPF policies prevent local traffic switching for any traffic (thus for broadcast/multicast traffic) some mechanism such as responding to ARP/ND based on local cache information or local multicast group handling is needed to ensure that upper layer protocol can run on the Ethernet PDU sessions.
The SMF may ask to get notified with the source MAC addresses used by the UE, e.g. if the PCF has subscribed to UE MAC address change notifications, as described in TS 23.503 [45].
In order to request the UPF to act as defined above, the SMF may, for each PDU Session corresponding to a Network Instance, set an Ethernet PDU Session Information in a DL PDR that identifies all (DL) Ethernet packets matching the PDU session. Alternatively, for unicast traffic the SMF may provide UPF with dedicated forwarding rules related with MAC addresses notified by the UPF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.6 Charging and Usage Monitoring Handling | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.6.1 General | The SMF shall support interfaces towards CHF and PCF. The SMF interacts with CHF and PCF based on information received from other control plane NFs and user plane related information received from the UPF.
QoS Flow level, PDU Session level and subscriber related information remain at the SMF and only usage information is requested from the UPF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.6.2 Activation of Usage Reporting in UPF | Triggered by the PCC rules received from the PCF or preconfigured information available at SMF, as well as from the CHF for online charging method via quota management mechanisms, the SMF shall provide Usage Reporting Rules to the UPF for controlling how usage reporting is performed.
The SMF shall request the report of the relevant usage information for Usage Monitoring, based on Monitoring Keys and triggers which are specified in TS 23.503 [45]. Each Usage Reporting Rule requested for usage monitoring control is associated with the PDR(s) whose traffic is to be accounted under this rule. The SMF shall generate the Usage Reporting Rule for each Monitoring-key within the active PCC Rule(s), either preconfigured or received from the PCF and also shall keep the mapping between them. Multiple Usage Reporting Rules may be associated with the same PDR.
The SMF shall request the report of the relevant usage information for offline and online charging, based on Charging keys and additional triggers which are specified in TS 32.255 [68]. Each Usage Reporting Rule requested for offline or online charging is associated with the PDR(s) whose traffic is to be accounted under this rule. The SMF shall generate the Usage Reporting Rule for each Charging key and Sponsor Identity (if applicable) within the active PCC Rule(s), either preconfigured or received from the PCF and also shall keep the mapping between them. Multiple Usage Reporting Rules may be associated with the same PDR.
The SMF function shall also provide reporting trigger events to the UPF for when to report usage information. The reporting trigger events (e.g. triggers, threshold information etc.) shall be supported for the PDU Session level reporting as well as on Rule level basis as determined by the SMF. The triggers may be provided as a volume, time or event to cater for the different charging/usage monitoring models supported by the TS 23.503 [45] for usage monitoring and by TS 32.255 [68] for converged offline and online charging. The SMF shall decide on the thresholds value(s) based on allowance received from PCF, CHF or based on local configuration. Other parameters for instructing the UPF to report usage information are defined in TS 29.244 [65].
When the PCC Rule attribute Service Data flow handling while requesting credit (specified in TS 23.503 [45]) indicates "non-blocking", the SMF shall request the report of the relevant usage information for the Charging key and Sponsor Identity (if applicable) and provide a default threshold value to the UPF while waiting for the quota from the CHF.
In some cases, the same Usage Reporting Rule can be used for different purposes (for both usage monitoring and charging), e.g. in the case that the same set of PDR(s), measurement method, trigger event, threshold, etc. apply. Similarly a reported measurement can be used for different purposes by the SMF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.6.3 Reporting of Usage Information towards SMF | The UPF shall support reporting of usage information to the SMF. The UPF shall be capable to support reporting based on different triggers, including:
- Periodic reporting with period defined by the SMF.
- Usage thresholds provided by the SMF.
- Report on demand received from the SMF.
The SMF shall make sure that the multiple granularity levels required by the reporting keys in the Usage Reporting rules satisfy the following aggregation levels without requiring a knowledge of the granularity levels by the UPF:
- PDU Session level reporting;
- Traffic flow (for both charging and usage monitoring) level reporting as defined by the reporting keys in the Usage Reporting Rule (see the description above).
Based on the mapping between Monitoring key and PCC rule stored at the SMF, the SMF shall combine the reported information with session and subscriber related information which is available at the SMF, for Usage Monitoring reporting over the corresponding Npcf interface (N7 reference point).
Based on the mapping between Charging key and Sponsor Identity (if applicable) and PCC rule stored at the SMF, the SMF shall combine the reported information with session and subscriber related information which is available at the SMF, for offline and online charging reporting over the corresponding charging interfaces.
This functionality is specified in TS 32.255 [68].
The usage information shall be collected in the UPF and reported to the SMF as defined in 5.8.2.6, based on Monitoring Keys and triggers which are specified in TS 23.503 [45]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.7 PDU Session and QoS Flow Policing | ARP is used for admission control (i.e. retention and pre-emption of the new QoS Flow). The value of ARP is not required to be provided to the UPF.
For every QoS Flow, the SMF shall determine the transport level packet marking value (e.g. the DSCP in the outer IP header) based on the 5QI, the Priority Level (if explicitly signalled) and optionally, the ARP priority level and provide the transport level packet marking value to the UPF.
For QoS Flows that are configured for PDU Set QoS handling, the SMF may additionally take into account the PDU Set Importance when determining the transport level packet marking values. In this case, the SMF provides a list of transport level packet marking values for the downlink direction to the UPF in a FAR, each of the transport level packet marking values corresponding to one or more PDU Set Importance values. When an I-SMF/I-UPF is inserted in the PDU Session, the I-SMF may instruct the I-UPF to derive the transport level packet marking of the outgoing N3 downlink packet based on the transport level packet marking of the incoming N9 downlink packet.
NOTE 1: It is recommended that the PDU Set Importance based transport level packet marking values applied by the UPF only vary the drop precedence between PDUs in the transport network nodes (e.g. IP routers) on the N3/N9 interfaces. This is needed to avoid causing packet reordering in the transport network when different transport level DSCP marking values are used for a single QoS Flow.
NOTE 2: The transport level packet marking values are provided on per-QoS Flow basis and it is up to operator deployments to enforce consistency of transport level marking in the transport network.
The SMF shall provide the Session-AMBR values of the PDU Session to the UPF so that the UPF can enforce the Session-AMBR of the PDU Session across all Non-GBR QoS Flows of the PDU Session.
SMF shall provide the GFBR and MFBR value for each GBR QoS Flow of the PDU Session to the UPF. SMF may also provide the Averaging window to the UPF, if Averaging window is not configured at the UPF or if it is different from the default value configured at the UPF.
In the case of 3GPP access, the SMF may decide to activate ECN marking for L4S by PSA UPF for the QoS Flow (see clause 5.37). In this case, the SMF shall send an ECN marking for L4S indicator to PSA UPF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.8 PCC Related Functions | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.8.1 Activation/Deactivation of predefined PCC rules | A predefined PCC rule is configured in the SMF.
The traffic detection filters, e.g. IP Packet Filter, required in the UP function can be configured either in the SMF and provided to the UPF, as service data flow filter(s), or be configured in the UPF, as the application detection filter identified by an application identifier. For the latter case, the application identifier has to be configured in the SMF and the UPF.
The traffic steering policy information can be only configured in the UPF, together with traffic steering policy identifier(s), while the SMF has to be configured with the traffic steering policy identifier(s).
Policies for traffic handling in the UPF, which are referred by some identifiers corresponding to the parameters of a PCC rule, can be configured in the UPF. These traffic handling policies are configured as predefined QER(s), FAR(s) and URR(s).
When a predefined PCC rule is activated/deactivated by the PCF, SMF shall decide what information has to be provided to the UPF to enforce the rule based on where the traffic detection filters (i.e. service data flow filter(s) or application detection filter), traffic steering policy information and the policies used for the traffic handling in the UPF are configured and where they are enforced:
- If the predefined PCC rule contains an application identifier for which corresponding application detection filters are configured in the UPF, the SMF shall provide a corresponding application identifier to the UPF;
- If the predefined PCC rule contains traffic steering policy identifier(s), the SMF shall provide a corresponding traffic steering policy identifier(s) to the UPF;
- If the predefined PCC rule contains service data flow filter(s), the SMF shall provide them to the UPF;
- If the predefined PCC rule contains some parameters for which corresponding policies for traffic handling in the UPF are configured in the UPF, the SMF shall activate those traffic handling policies via their rule ID(s).
The SMF shall maintain the mapping between a PCC rule received over Npcf and the flow level PDR rule(s) used on N4 interface. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.8.2 Enforcement of Dynamic PCC Rules | The application detection filters required in the UPF can be configured either in the SMF and provided to the UPF as the service data flow filter, or be configured in the UP function identified by an application identifier.
When receiving a dynamic PCC rule from the PCF which contains an application identifier and/or parameters for traffic handling in the UPF:
- if the application detection filter is configured in the SMF, the SMF shall provide it in the service data flow filter to the UPF, as well as parameters for traffic handling in the UPF received from the dynamic PCC rule;
- otherwise, the application detection filters is configured in UPF, the SMF shall provide to UPF with the application identifier and the parameters for traffic handling in the UPF as required based on the dynamic PCC rule.
The SMF shall maintain the mapping between a PCC rule received over Npcf and the flow level PDR(s) used on N4 interface. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.8.3 Redirection | The uplink application's traffic redirection may be enforced either in the SMF (as specified in 5.8.2.5 Control of user plane forwarding) or directly in the UPF. The redirect destination may be provided in the dynamic PCC rule or be preconfigured, either in the SMF or in the UPF.
When receiving redirect information (redirection enabled/disabled and redirect destination) within a dynamic PCC rule or being activated/deactivated by the PCF for the predefined redirection policies, SMF shall decide whether to provide and what information to be provided to the UPF based on where the redirection is enforced and where the redirect destination is acquired/preconfigured. When redirection is enforced in the UPF and the redirect destination is acquired from the dynamic PCC rule or is configured in the SMF, SMF shall provide the redirect destination to the UPF. When redirection is enforced in the SMF, SMF shall instruct the UPF to forward applicable user plane traffic to the SMF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.8.4 Support of PFD Management | The NEF (PFDF) shall provide PFD(s) to the SMF on the request of SMF (pull mode) or on the request of PFD management from NEF (push mode), as described in TS 23.503 [45]. In addition, the NEF (PFDF) may subscribe to NWDAF to be notified or request to get PFD "Determination analytics" for known applications (as specified in TS 23.288 [86]) and may decide whether to create, update, or delete PFD(s) based on the NWDAF analytics as specified in TS 23.503 [45]. The SMF shall provide the PFD(s) to the UPF, which have active PDR(s) with the application identifier corresponding to the PFD(s).
The SMF supports the procedures in clause 4.4.3.5 of TS 23.502 [3], for management of PFDs. PFD(s) is cached in the SMF and the SMF maintains a caching timer associated to the PFD(s). When the caching timer expires and there's no active PCC rule that refers to the corresponding application identifier, the SMF informs the UPF to remove the PFD(s) identified by the application identifier using the PFD management message.
When a PDR is provided for an application identifier corresponding to the PFD(s) that are not already provided to the UPF, the SMF shall provide the PFD(s) to the UPF (if there are no PFD(s) cached, the SMF retrieves them from the NEF (PFDF) as specified in TS 23.503 [45]). When any update of the PFD(s) is received from NEF (PFDF) by SMF (using "push" or "pull" mode) and there are still active PDRs in UPF for the application identifier, the SMF shall provision the updated PFD set corresponding to the application identifier to the UPF using the PFD management message.
NOTE 1: SMF can assure not to overload N4 signalling while managing PFD(s) to the UPF, e.g. forwarding the PFD(s) to the right UPF where the PFD(s) is enforced.
When the UPF receives the updated PFD(s) from either the same or different SMF for the same application identifier, the latest received PFD(s) shall overwrite any existing PFD(s) stored in the UPF.
NOTE 2: For the case a single UPF is controlled by multiple SMFs, the conflict of PFD(s) corresponding to the same application identifier provided by different SMF can be avoided by operator enforcing a well-planned NEF (PFDF) and SMF/UPF deployment.
When a PFD is removed/modified and this PFD was used to detect application traffic related to an application identifier in a PDR of an N4 session and the UPF has reported the application start to the SMF as defined in clause 4.4.2.2 of TS 23.502 [3] for the application instance corresponding to this PFD, the UPF shall report the application stop to the SMF for the corresponding application instance identifier if the removed/modified PFD in UPF results in that the stop of the application instance is not being able to be detected.
If the PFDs are managed by local O&M procedures, PFD retrieval is not used; otherwise, the PFDs retrieved from NEF (PFDF) override any PFDs pre-configured in the SMF. When all the PFDs retrieved from the NEF (PFDF) for an application identifier are removed, the pre-configured PFDs are used. The SMF shall provide either the PFDs retrieved from NEF (PFDF) or the pre-configured PFDs for an application identifier to the UPF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.9 Functionality of Sending of "End marker" | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.9.0 Introduction | Sending of "end marker" is a functionality which involve SMF and UPF in order to assist the reordering function in the Target RAN. As part of the functionality, constructing of end marker packets can either be done in the SMF or in the UPF, as described in clauses 5.8.2.9.1 and 5.8.2.9.2. Whether constructing of end marker packets is performed by SMF or UPF is determined by network configuration. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.9.1 UPF Constructing the "End marker" Packets | In the case of inter NG-RAN Handover procedure without UPF change, SMF shall indicate the UPF to switch the N3 path(s) by sending an N4 Session Modification Request message with the new AN Tunnel Info of NG RAN and in addition, provide an indication to the UPF to send the end marker packet(s) on the old N3 user plane path.
On receiving this indication, the UPF shall construct end marker packet(s) and send it for each N3 GTP-U tunnel towards the source NG RAN after sending the last PDU on the old path.
In the case of inter NG-RAN Handover procedure with change of the UPF terminating N3, the SMF shall request the UPF with N9 reference point to the UPF terminating N3 to switch the N9 user plane path(s) by sending an N4 Session Modification Request message (N4 session ID, new CN Tunnel Info of the UPF terminating N3) and in addition, provide an indication to this UPF to send the end marker packet(s) on the old path.
On receiving this indication, the UPF shall construct end marker packet(s) and send it for each N9 GTP-U tunnel towards the source UPF after sending the last PDU on the old path.
On receiving the end marker packet(s) on N9 GTP-U tunnel, source UPF shall forward the end marker packet(s) and send it for each N3 GTP-U tunnel towards the source NG RAN. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.9.2 SMF Constructing the "End marker" Packets | UPF referred in this clause is the UPF terminates N3 reference point.
It is assumed that the PDU Session for the UE comprises of an UPF that acts as a PDU Session Anchor and an intermediate UPF terminating N3 reference point at the time of this Handover procedure.
In the case of inter NG-RAN Handover procedure without UPF change, SMF shall indicate the UPF to switch the N3 path(s) by sending an N4 Session Modification Request message (N4 session ID, new AN Tunnel Info of NG RAN). After sending the last PDU on the old path, UPF shall replace the old AN Tunnel Info with the new one and responds with an N4 Session Modification Response message to acknowledge the success of path switch.
When the path switch is finished, SMF constructs the end marker packet(s) and sends it to the UPF. UPF then forwards the packet(s) to the source NG RAN.
In the case of inter NG-RAN Handover procedure with UPF change, SMF shall indicate the PSA UPF to switch the N9 user plane path(s) by sending an N4 Session Modification Request message (N4 session ID, new CN Tunnel Info of UPF). After sending the last PDU on the old N9 path, PSA UPF shall replace the old CN Tunnel Info with the new one and responds with an N4 Session Modification Response message to acknowledge the success of path switch.
When the path switch is finished, SMF constructs the end marker packet(s) and sends it to PSA UPF. PSA UPF then forwards the packet(s) to the source UPF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.10 UP Tunnel Management | 5GC shall support per PDU Session tunnelling on N3 between (R)AN and UPF and N9 between UPFs. If there exist more than one UPF involved for the PDU Session, any tunnel(s) between UPFs (e.g. in the case of two UPFs, between the UPF that is an N3 terminating point and the UPF for PDU Session Anchor) remains established when a UE enters CM-IDLE state. In the case of downlink data buffering by UPF, when mobile terminated (MT) traffic arrives at the PDU Session Anchor UPF, it is forwarded to the UPF which buffer the data packet via N9 tunnel. See clause 5.8.3 for more details on UPF buffering. In the case of Home Routed roaming, the SMF in HPLMN is not aware of the UP activation state of a PDU Session.
When the UP connection of the PDU Session is deactivated, the SMF may release the UPF of N3 terminating point. In that case the UPF (e.g. the Branching Point/UL CL or PDU Session Anchor) connecting to the released UPF of N3 terminating point will buffer the DL packets. Otherwise, when the UPF with the N3 connection is not released, this UPF will buffer the DL packets.
When the UP connection of the PDU Session is activated due to a down-link data arrived and a new UPF is allocated to terminate the N3 connection, a data forwarding tunnel between the UPF that has buffered packets and the newly allocated UPF is established, so that the buffered data packets are transferred from the old UPF that has buffered packets to the newly allocated UPF via the data forwarding tunnel.
For a PDU Session whose the UP connection is deactivated and the SMF has subscribed the location change notification, when the SMF is notified of UE's new location from the AMF and detects that the UE has moved out of the service area of the existing intermediate UPF, the SMF may decide to maintain the intermediate UPF, remove the established tunnel between UPFs (in the case of removal of the intermediate UPF) or reallocate the tunnel between UPFs (in the case of reallocation of the intermediate UPF). |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.11 Parameters for N4 session management (moved) | The parameters used by SMF to control the functionality of the UPF as well as to inform SMF about events occurring at the UPF are described in clause 5.8.5. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.12 Reporting of the UE MAC addresses used in a PDU Session | For Ethernet PDU Session type, the SMF may control the UPF to report the different MAC (Ethernet) addresses used as source address of frames sent UL by the UE in a PDU Session. These MAC addresses are called UE MAC addresses.
This control and the corresponding reporting takes place over N4.
NOTE: This is e.g. used to support reporting of all UE MAC addresses in a PDU Session to the PCF as described in clause 5.6.10.2.
The UPF reports the removal of a UE MAC address based on the detection of absence of traffic during an inactivity time. The inactivity time value is provided by the SMF to the UPF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.13 Support for 5G VN group communication | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.13.0 General | The SMF may configure the UPF(s) to apply different traffic forwarding methods to route traffic between PDU Sessions for a single 5G VN group. For example, depending on the destination address, some packet flows may be forwarded locally, while other packet flows are forwarded via N19 and other packet flows are forwarded to N6.
If a single SMF serves the DNN/S-NSSAI of the 5G VN group, the UPF local switching, N6-based forwarding and N19-based forwarding methods described in clause 5.29.4 are coordinated by the SMF. If an SMF set serves the DNN/S-NSSAI of the 5G VN group, implementation based mechanisms can be used between SMF(s) that are part of the SMF set for controlling the connectivity between the PSA UPFs of the UE members of the 5G VN group.
When a 5G VN group communication is extended in a wide area, bigger than the service area of any SMF set serving the DNN/S-NSSAI of the 5G VN group, multiple SMF sets might control the PDU Sessions of the UE members of the 5G VN group. In this case, N6/N19 connectivity between PSA UPFs of the UE members of the 5G VN group controlled by different SMF sets, is achieved via OAM configuration. As a deployment option, a subset of the UPFs controlled by an SMF Set may be configured with the N6/N19 connectivity to enable 5G VN group communication across SMF Sets. N6 connectivity between PSA UPFs via a DN may also exist.
5G VN group communication includes one to one communication and one to many communication. One to one communication supports forwarding of unicast traffic between two UEs within a 5G VN, or between a UE and a device on the DN. One to many communication supports forwarding of multicast traffic and broadcast traffic from one UE (or device on the DN) to many/all UEs within a 5G VN and devices on the DN.
Traffic forwarding within the 5G VN group is realized by using a UPF internal interface ("5G VN internal") and a two-step detection and forwarding process. In the first step, the packets received from any 5G VN group member (via it's PDU Session, via N6 or via N19) are forwarded to the UPF internal interface (i.e. Destination Interface set to "5G VN internal"). In the second step, PDRs installed at the UPF internal interface (i.e. Source Interface set to "5G VN internal") detect the packet and forward it to the respective 5G VN group member (via it's PDU Session, via N6 or via N19). The details of the PDR and FAR configuration are described in the following clauses.
For UEs belonging to the same 5G VN group and having PDU Sessions that correspond to N4 Sessions in the same PSA UPF, the following applies for traffic that is sent from one of these UEs to another one of these UEs using local switching: The incoming traffic for one PDU Session will match the corresponding N4 Session's PDR(s) of the source PDU Session (based on GTP-U header information). The traffic is then sent back to classification in that UPF (via the internal interface) and will match another N4 Session corresponding to the destination PDU Session (based on destination address in the PDU). The PDU is then forwarded to the target UE.
If 5G VN group members' PDU Sessions are served by different PSA UPFs and N19-based forwarding is applied, the SMF creates a group-level N4 Session with each involved UPF to enable N19-based forwarding and N6-based forwarding. When the traffic is then sent back to classification in that UPF (via the internal interface) it may match group-level N4 Session corresponding to the 5G VN group (based on destination address in the PDU or a default PDR rule with match-all packet filter). The PDU is then forwarded to N6 or to the UPF indicated in the group-level N4 Session via corresponding N19 tunnel. This enables the PDU to be sent to the target group member in the other UPF or to the device in the DN.
In the case of N19-based forwarding is not applied for a 5G VN group, group level N4 session is not required.
If more than one 5G VN group has to be supported in the PLMN, the N4 rule attribute Network Instance is used in addition to the UPF internal interface and set to a value representing the 5G VN group. This keeps the traffic of different 5G VN groups separate from each other and thus enables isolation of the 5G VN group communication during the packet detection and forwarding process. The SMF shall provide the PDRs and FARs related to the UPF internal interface as follows whenever more than one 5G VN group has to be supported in the PLMN:
- The FAR with Destination Interface set to "5G VN internal" shall also contain the Network Instance set to the value representing the 5G VN group.
- The PDR with Source Interface set to "5G VN internal" shall also contain the Network Instance set to the value representing the 5G VN group.
Forwarding Ethernet unicast traffic towards the PDU Session corresponding to the Destination MAC address of an Ethernet frame may correspond:
- either to the SMF explicitly configuring DL PDR(s) with the MAC addresses detected by the UPF on PDU Sessions and reported to the SMF; this is further described in clause 5.8.2.13.1;
- or to the SMF relying on MAC address learning in UPF as defined in clause 5.8.2.5.3. To request this UPF behaviour the SMF sets the Ethernet PDU Session Information indication in the DL PDR of the "5G VN internal" interface related with a 5G VN group. This may apply in the case that all PDU Sessions related with this 5G VN group are served by the same PSA or by multiple PSAs not inter-connected via N19.
For Ethernet traffic on 5G-VN, in the former case above where SMF explicitly configures DL PDR with the MAC addresses detected on PDU Sessions supporting a 5G VN group, the SMF acts as a central controller which is responsible for setting up the forwarding rules in the UPFs so that it avoids forwarding loops. The SMF becomes aware of the MAC addresses in use within a 5G VN group by the UPF's reporting of the MAC addresses. The SMF is responsible to react to topology changes in the Ethernet network. Local switching without SMF involvement is not specified for a 5G-VN when different PDU Sessions related with this 5G VN group may be served by different PSA(s) connected over N19.
NOTE: The mechanisms described above implies signalling on N4 Sessions related with a VN group each time a new MAC address is detected as used (or no more used) within a PDU Session related with this 5G VN group. Hence the usage of the solution with SMF explicitly configuring DL PDR with the MAC addresses defined in this release can raise signalling scalability issues for large VN groups with lots of devices (MAC addresses) served by PDU sessions related with this VN group. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.13.1 Support for unicast traffic forwarding of a 5G VN | To enable unicast traffic forwarding in a UPF, the following applies:
- The SMF provides for each 5G VN group member's N4 Session (i.e. N4 Session corresponding to PDU Session) the following N4 rules that enable the processing of packets received from this UE.
- in order to detect the traffic, a PDR containing Source Interface set to "access side" and CN Tunnel Information set to PDU Session tunnel header (i.e. N3 or N9 GTP-U F-TEID); and
- in order to forward the traffic, a FAR containing Destination Interface set to "5G VN internal".
- The SMF provides for each 5G VN group member's N4 Session (i.e. N4 session corresponding to PDU Session) the following N4 rules that enable the processing of packets towards this UE.
- in order to detect the traffic, a PDR containing Source Interface set to "5G VN internal" and Destination Address set to the IP/MAC address (es) of this 5G VN group member; and
- in order to forward the traffic, a FAR containing Outer Header Creation indicating the N3/N9 tunnel information and Destination Interface set "access side".
- If N19-based forwarding is applied, the SMF configures the group-level N4 Session for processing packets received from a N19 tunnel with the following N4 rules for each N19 tunnel.
- in order to detect the traffic, a PDR containing Source Interface set to "core side" and CN Tunnel Information set to N19 tunnel header (i.e. N19 GTP-U F-TEID); and
- in order to forward the traffic, a FAR containing Destination Interface set to "5G VN internal".
- If N19-based forwarding is applied, the SMF configures the group-level N4 Session for processing packets towards 5G VN group members anchored at other UPFs with the following N4 rules for each N19 tunnel.
- in order to detect the traffic, a PDR containing Source Interface set to "5G VN internal" and Destination Address set to the IP/MAC address (es) of UEs anchored at the peer UPF of this N19 tunnel (e.g. based on the IP address range supported by the peer UPF); and
- in order to forward the traffic to a 5G VN group member anchored at another UPF via the N19 tunnel, a FAR containing Outer Header Creation indicating the N19 tunnel information, Destination Interface set to "core side".
- The SMF configures the group-level N4 Session for processing packets received from a 5G VN group member connected via N6 with the following N4 rules.
- in order to detect the traffic, a PDR containing Source Interface set to "core side" and Source Address set to the IP/MAC address (es) of this 5G VN group member; and
- in order to forward the traffic, a FAR containing Destination Interface set to "5G VN internal".
- The SMF configures the group-level N4 Session for processing packets towards a 5G VN group member connected via N6 or packets towards a device residing in DN with the following N4 rules.
- in order to detect the traffic, a PDR containing Source Interface set to "5G VN internal" and Destination Address set to the IP/MAC address (es) of this 5G VN group member; and
- in order to forward the traffic to the 5G VN group member or device via N6, a FAR containing Destination Interface set to "core side".
- The SMF shall update N4 rules for group-level N4 Session to enable correct forwarding of packets towards UE who's PSA UPF has been reallocated and address is unchanged.
- The SMF may also configure the following N4 rules for the group-level N4 Session to process packets with an unknown destination address:
- in order to detect the traffic, a PDR containing Source Interface set to "5G VN internal", a match-all Packet Filter and a Precedence set to the lowest precedence value; and
- in order to process the traffic, a FAR containing Destination Interface set to "core side" to route the traffic via N6 by default, or in the case of local SMF configuration that N6-based forwarding is not applied a FAR instructing the UPF to drop the traffic. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.13.2 Support for unicast traffic forwarding update due to UE mobility | To enable the service continuity when the PSA UPF serving the UE changed, the following applies:
- Keep the UE address unchanged if N6-based forwarding is not used.
- Configure the UE's N4 Session with N4 rules (PDR, FAR) to detect and forward the traffic to this UE via its PDU Session tunnel(i.e. N3 tunnel) on the target PSA UPF.
- If N19-based forwarding is applied: To switch the traffic towards this UE from the source PSA UPF to the target PSA UPF for N19-based forwarding, the SMF deletes the N4 rule (PDR) that detects the traffic towards this UE in the group-level N4 Session at UPFs involved in the 5G VN group (except the source PSA UPF), then adds or updates the PDR that detects the traffic towards this UE with the FAR containing the N19 tunnel information of the target PSA UPF in the group-level N4 Session at UPFs involved in the 5G VN group (except the target PSA UPF). |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.13.3 Support for user plane traffic replication in a 5G VN | 5.8.2.13.3.1 User plane traffic replication based on UPF internal functionality
For Ethernet PDU Sessions, the SMF may instruct the UPF to route traffic to be replicated as described in clause 5.8.2.5.
For IP PDU Session types, the SMF may instruct the UPF to manage IP multicast traffic as described in clauses 4.6.6 and 7.7.1 of TS 23.316 [84]. The UPF replicates the IP multicast traffic received from PDU Sessions or N6 interface and sends the packets over other PDU Sessions and other N6 interface subscribed to the IP Multicast groups.
Mechanisms described in clauses 4.6.6 and 7.7.1 of TS 23.316 [84] apply to support 5G VN group communication with following clarifications:
- These mechanisms are not limited to Wireline access and can apply on any access,
- IP Multicast traffic allowed for a PDU Session is not meant for IPTV services reachable over N6,
- IGMP /MLD signalling does not relate with STB or 5G-RG: Clauses 4.6.6 and 7.7.1 of TS 23.316 [84], apply to UE members of a 5G VN group instead of 5G-RG and
- Clauses 7.7.1.1.2 and 7.7.1.1.4 of TS 23.316 [84] are not applicable to 5G VN groups: members of the 5G VN groups may receive any multicast traffic associated with the (DNN, S-NSSAI) of the 5G VN group.
- UPF exchange of signalling such as PIM (Protocol-Independent Multicast) may apply as defined in TS 23.316, with following clarification:
- PIM signalling is generally exchanged over N6 but may be sent towards the PDU Session supporting the source address of multicast traffic identified by IGMP / MLD signalling for Source Specific Multicast. In the case of IGMP / MLD signalling not related with Source Specific Multicast no PIM signalling is sent towards any PDU Session
5.8.2.13.3.2 User plane traffic replication based on PDRs with replication instructions
Alternatively, for IP or Ethernet type data communication, the SMF instructs the UPF via PDRs and FARs how to replicate user plane traffic.
The mechanism is supported in the following conditions:
- When N19 is used, there is a full mesh of N19 tunnels between UPFs controlled by each SMF Set serving the 5G VN group;
- There is no support for forwarding a broadcast/multicast packet with source address not known to SMF/UPF.
- Each UPF supports one N6 interface instance towards the data network, or only supports N19-based forwarding without N6;
- Multicast group formation of selected members of a 5G VN for Ethernet type data communication is not described in this release of the specification.
In this case, when the UPF receives a broadcast packet of a 5G VN group from N19 or N6, it shall distribute it to all 5G VN group members connected to this UPF. When the UPF receives a broadcast packet from a UE (source UE) via PDU Session associated with a 5G VN group, it shall distribute it to:
- All 5G VN group members (except the source UE) connected to this UPF via local switch; and
- All 5G VN group members connected to other UPFs via N19-based forwarding or N6-based forwarding; and
- The devices on the DN via N6-based forwarding.
To enable broadcast traffic forwarding of a 5G VN group in a UPF, the following applies:
- The SMF provides group-level N4 Session and each 5G VN group member' N4 Session with the PDR that detect the broadcast packet sent via "internal interface". When UPF receives the broadcast packets sent via "internal interface", it matches the broadcast packet against all PDRs installed at the "internal interface". A successful matching with a PDR that detect the broadcast packet instructs the UPF to continue the lookup of the other PDRs. A matching PDR that detects the broadcast packet shall instruct the UPF to duplicate the broadcast packet and perform processing (using associated FAR, URR, QER) on the copy instead of the original packet if the broadcast packet does not satisfy the packet replication skip information, otherwise the PDR instructs the UPF to skip the processing of the broadcast packet.
- The broadcast packets received from N19 or N6 are forwarded to the UPF internal interface together with a N19 or N6 indication.
- The SMF provides for each 5G VN group member' N4 Session (i.e. N4 session corresponding to PDU Session) the following N4 rules that enable the processing of broadcast packets towards this UE.
- in order to detect the traffic, a PDR containing Source Interface set to "5G VN internal", Destination Address set to the broadcast address, the Packet replication skip information set to the IP/MAC address (es) of this 5G VN group member and the indication to carry on matching; and
- in order to forward the traffic, a FAR containing Outer Header Creation indicating the PDU Session tunnel information and Destination Interface set "access side".
- The SMF configures the group-level N4 Session for processing packets received from a N19 tunnel with the following N4 rules for each N19 tunnel.
- in order to detect the traffic, a PDR containing Source Interface set to "core side", Destination Address set to the broadcast address and CN Tunnel Information set to N19 tunnel header (i.e. N19 GTP-U TEID); and
- in order to forward the traffic, a FAR containing Destination Interface set to "5G VN internal", Outer Header Creation with the N19 indication.
- The SMF provides for the group-level N4 Session the following N4 rules that enable the processing of broadcast packets towards the other UPFs.
- in order to detect the traffic, a PDR containing Source Interface set to "5G VN internal", Destination Address set to the broadcast address, the Packet replication skip information set to the N19 indication and the indication to carry on matching; and
- in order to forward the traffic to each involved UPF via the corresponding N19 tunnel, a FAR containing "Duplication" instruction, Outer Header Creation indicating the N19 tunnel information, Destination Interface set to "core side".
- The SMF configures the group-level N4 Session for processing packets received from N6 with the following N4 rules.
- in order to detect the traffic, a PDR containing Source Interface set to "core side" and Destination Address set to the broadcast address; and
- in order to forward the traffic, a FAR containing Destination Interface set to "5G VN internal", Outer Header Creation with the N6 indication.
- The SMF provides for the group-level N4 Session the following N4 rules that enable the processing of broadcast packets towards N6.
- in order to detect the traffic, a PDR containing Source Interface set to "5G VN internal" and Destination Address set to the broadcast address and the Packet replication skip information set to the N6 indication; and
- in order to forward the traffic to N6, a FAR containing Destination Interface set to "core side".
In this case, to enable multicast traffic forwarding of a 5G VN group in a UPF, broadcast traffic forwarding of a 5G VN applies to multicast traffic forwarding of a 5G VN with the following modifications:
- The SMF installs PDRs for the multicast address instead of the broadcast address.
- The PDRs and FARs are installed for PDU Sessions corresponding to the members of the multicast group.
- In addition, the SMF installs the PDR identifying IGMP/MLD signalling for each 5G VN group member' N4 Session and a URR with a Reporting Trigger set to "IGMP reporting" for IGMP or set to "MLD reporting" for MLD. Based on the IP Multicast address in "IP multicast join" or "IP multicast leave" reports received from UPF, the SMF manipulates (delete or add) the PDR identifying the multicast traffic for the reported IP Multicast address at the corresponding 5G VN group member' N4 Session and if required at the group-level N4 Session at the UPF(s) of the 5G VN group. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.14 Inter PLMN User Plane Security functionality | Operators can deploy UPF(s) supporting the Inter PLMN User Plane Security (IPUPS) functionality at the border of their network to protect their networks from invalid inter PLMN N9 traffic.
The IPUPS functionality forwards GTP-U packets (received via the N9 interface) only if they belong to an active PDU Session and are not malformed, as described in TS 33.501 [29].
The SMF can activate the IPUPS functionality together with other UP functionality in the same UPF, or insert a separate UPF in the UP path for the IPUPS functionality. In both cases the UPF with IPUPS functionality is controlled by the SMF via the N4 interface. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.15 Void | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.16 Support for L2TP tunnelling on N6 | If requested by the SMF during N4 Session Establishment, the UPF (PSA) may setup L2TP towards an L2TP network server (LNS) in the DN and tunnel the PDU Session user plane traffic in this L2TP tunnel. In this case the UPF acts as a L2TP access concentrator (LAC).
To enable this, the SMF may provide L2TP information to the UPF, such as LNS IP address and/or LNS host name, as described in TS 29.244 [65]. This L2TP information may be configured on the SMF as part of the DNN configuration or received from the DN-AAA Server during secondary authentication/authorization, as described in clause 5.6.6. Alternatively, the L2TP tunnel parameters may be configured in the UPF Function. The L2TP tunnel parameters include necessary parameters for setting up L2TP tunnel towards the LNS (e.g. LNS address, tunnel password, etc.).
In addition, the SMF may provide PAP/CHAP authentication information to the UPF, for use in L2TP session establishment, in case it was received from the UE in the PDU Session Establishment Request.
When L2TP is to be used for a PDU Session, the SMF may select a UPF based upon support of this feature. The SMF determines whether the UPF supports this feature via N4 capability negotiation during N4 Association Setup or via NRF discovery.
If SMF requests the UPF to allocate UE IP address, as described in clause 5.8.2.2.1, the UPF (LAC) may retrieve this IP address from the LNS. In addition, if the SMF requests the UPF to provide DNS address(es), the UPF (LAC) may request the LNS to provide DNS address(es) and report such DNS address(es) to the SMF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.17 Data exposure via Service Based interface | The UPF may expose information by means of UPF Event Exposure service as described in TS 23.502 [3] clause 5.2.26.2, via a service-based interface directly. The NF consumers, which may receive UPF event notifications, are AF/NEF, TSNAF/TSCTSF, SMF and NWDAF/DCCF/MFAF.
When the UPF supports the data exposure via the service based interface, it may register its NF profile to the NRF including the UPF Event Exposure services and the related Event ID(s).
For data collection from UPF (see clause 4.15.4.5 of TS 23.502 [3]), NF consumers can do the subscription to the UPF either directly or indirectly via SMF. As described in clause 4.15.4.5.1 of TS 23.502 [3], for User Data Usage events (i.e. User Data Usage Measures and User Data Usage Trends), an NF consumer should subscribe to the UPF Event Exposure service directly if target of data collection is "any UE" or if target of data collection is a UE IP address and if the subscription is not including any of the following parameters: AoI, BSSID/SSID and DNAI. Otherwise, the NF consumer shall subscribe indirectly via SMF.
NOTE 1: Direct subscription to UPF is more efficient, therefore it is recommended that NF consumer subscribes directly to UPF whenever possible.
NOTE 2: The UE IP address is used to discover the PSA UPF serving the particular UE IP address. The NF consumer can only use the UE IP address to discover PSA UPF(s) that serve the corresponding IPv4 address/IPv6 prefix range and register the corresponding information in the NRF.
Upon release of an N4 Session, the UPF implicitly terminates subscriptions for a UE related to the N4 Session. When the N4 Session to the UPF is released and the UPF received the Subscription termination reporting indication, the UPF shall send a notification with a subscription termination indication and an optional cause code to the UPF event consumer. When the N4 Session to the UPF is released, the UPF may report to the consumer any data that has been collected but not sent to the consumer yet, if UPF received the Remaining data reporting indication and/or based on local configuration (see clause 4.15.4.5 of TS 23.502 [3]).
To alleviate the load of UPF due to frequent event notification for data collection related events, the event subscription may include Reporting suggestion information. The Reporting suggestion information includes Reporting urgency information and Reporting window information. Reporting urgency information represents whether this event report can be delay tolerant, i.e. the event report can be delayed. If the Reporting urgency information indicates "delay tolerant", the Reporting window is also provided, which defines the last valid reporting time and UPF shall report the event before that time. If the Reporting suggestion information allows this, the UPF can concatenate several event reports (of the same event) to the same notification endpoint into one notification message.
The UPF may also expose UE information by means of the Nupf_GetUEPrivateIPaddrAndIdentifiers service as described in clause 5.2.26.3 of TS 23.502 [3]. An UPF which is deployed with NAPT (Network Address Port Translation) functionality may support to provide the 5GC UE IP address to NEF based on NEF request containing public IP address and port number using the Nupf_GetUEPrivateIPaddrAndIdentifiers service as described in clause 4.15.10 of TS 23.502 [3] for AF specific UE ID retrieval.
The UPF event exposure service may allow NF consumer to obtain one NATed UE public IP address and Port number for a particular PDU Session, based on the UE private IP address allocated by 5GC. An UPF which is deployed with NAT functionality may support to provide the UE public IP address and port number to consumer based on Nupf_EventExposure_Subscribe request as defined in clause 5.2.26.2.3 of TS 23.502 [3]. For information flow for getting UE public IP address and port number, see clause 6.2.8.2.4 of TS 23.288 [5]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.18 QoS Flow related QoS monitoring and reporting | The SMF may configure the UPF to perform QoS monitoring for a QoS Flow and to report the monitoring results with the help of the following parameters provided in the Session Reporting Rule (SRR) described in clause 5.8.5.11:
- QoS monitoring parameter(s) indicating the subject of the QoS monitoring as defined in clause 5.45;
NOTE 1: Clause 5.45 contains specific description about the UPF configuration for QoS monitoring for the respective QoS monitoring parameter.
- Reporting period indicating the time interval in which a new measurement result and a potential report has to be available. Generally, if no measurement result is available to the UPF within the Reporting period, the UPF shall report a measurement failure; however, for some QoS monitoring parameters (e.g. congestion information, PDV and data rate, available bitrate), the measurement failure report is not applicable.
- Reporting frequency indicating the type of the reporting as "periodic" or "event triggered":
- If the Reporting frequency indicates "periodic", the UPF shall send a report each time the reporting period is over.
- If the Reporting frequency indicates "event triggered", a Reporting threshold for each parameter in the QoS monitoring parameter(s) and a Minimum waiting time are provided as well. The UPF shall send a report when the measurement result matches or exceeds the indicated Reporting threshold. Subsequent reports should not be sent by the UPF during the Minimum waiting time. The UPF shall continue to report a measurement result that matches or exceeds the indicated Reporting Threshold when the Minimum waiting time is over.
NOTE 2: As an implementation option, the UPF can be configured to send subsequent report(s) during the Minimum waiting time, e.g. if the UPF determines that this report is considerably different from the previous report.
- (Optional) Target of the reporting and Indication of direct event notification indicating that the UPF shall send the reports to a different NF than the SMF (e.g. to the NEF/AF or the NWDAF/DCCF/MFAF). The NF is identified by a Notification Target Address and a Notification Correlation ID. The SMF can also indicate that the UPF shall send the reports to both, the NF indicated by the Target of reporting and to the SMF. If so, the UPF shall send the reports to the SMF as well. If the Indication of direct event notification is not provided, the UPF shall send the reports to the SMF.
- (Optional) Reporting suggestion information as defined in clause 5.8.2.17 applicable to Target of the reporting to reduce the UPF performance impacts. The SMF includes Reporting Suggestion information if received in a subscription to UPF QoS Monitoring event sent by the consumer via SMF for UPF Data Collection (see clause 4.15.4.5 of TS 23.502 [3]).
- (Optional) Indication of QoS Flow associated with the default QoS Rule (see clause 4.15.4.5.1 of TS 23.502 [3]). The UPF shall forward this indication, that the QoS monitoring report is for the QoS Flow associated with the default QoS Rule, in the Nupf_EventExposure_Notify service operation when sending reports.
- (Optional) Remaining data reporting indication. The SMF includes this indication if received in a subscription to UPF QoS Monitoring event sent by the consumer via SMF for UPF Data Collection (see clause 4.15.4.5). It indicates that the consumer requests that, at N4 session release, UPF reports any collected data not yet sent. UPF may send any collected data not yet sent to the UPF event consumer considering the Remaining data reporting indication and/or local configuration as described in clause 4.15.4.5.6 of TS 23.502 [3].
The UPF shall send the QoS Monitoring Report as follows:
- when the UPF sends reports to the SMF, the UPF shall use QoS Monitoring Reports as described in clause 5.8.5.12; and/or
- When the UPF sends reports to a different NF than the SMF (e.g. the NEF/AF or the NWDAF/DCCF/MFAF), the UPF shall use the Nupf_EventExposure_Notify service operation described in clause 5.2.26.2.2 of TS 23.502 [3]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.19 Explicit Buffer Management | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.19.1 General | 5GC supports buffering of UE's downlink packets for deactivated PDU Sessions.
Support for buffering in the UPF is mandatory and optional in the SMF.
When the UP connection of a PDU Session is deactivated, buffering in UPF can be activated by the SMF. If the SMF supports buffering capability, the SMF can decide to activate buffering in SMF instead of buffering in UPF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.19.2 Buffering at UPF | When the SMF decided to activate buffering in UPF, the SMF shall inform the UPF to start buffering packets for this PDU Session.
The SMF provides instructions to the UPF for at least the following behaviour:
- buffer downlink packets with the following additional options:
- reporting the arrival of first downlink packet (for a QoS Flow or a service data flow) and/or
- reporting the first discarded downlink packet (for a service data flow), or
- drop downlink packets with the following additional options:
- reporting the first discarded downlink packet (for a service data flow).
- buffer uplink packets.
When the SMF instructs the UPF for a service data flow to buffer downlink packets and to report the first discarded downlink packet, the SMF shall also instruct the UPF to report the arrival of the first downlink packet for this service data flow to enable the SMF check if this is also the first report for the QoS Flow (as described below). Based on local policy and/or an indication from the AMF, e.g. the RAT type of REDCAP or the CN based MT handling indication, the SMF may also instruct the UPF to report the DL data size in case of arrival of the first downlink packet.
Buffering in the UPF may be configured based on timers or the amount of downlink data to be buffered. The SMF decides whether buffering timers or amount of downlink data are handled by the UPF or SMF.
After starting buffering, when the first downlink packet (of a QoS Flow or a service data flow) arrives, UPF shall inform the SMF if it is setup to report. UPF sends a Downlink Data Report to the SMF via N4 unless specified otherwise and indicates the PDR by which the downlink packet was received. If the SMF receives a Downlink Data Report for a service data flow, the SMF shall also check if this is the first report for the QoS Flow corresponding to the PDR. If so, the SMF shall also proceed as described in clause 5.4.3.1.
After starting buffering, when the first downlink packet (of a service data flow) in a configured period of time that has been buffered is discarded by the UPF because the configured buffering time or amount of downlink data to be buffered is exceeded, the UPF shall inform the SMF if it is setup to report. UPF sends a Downlink Data Report to the SMF via N4 and indicates the PDR by which the discarded downlink packet was received.
A new report is sent if the SMF terminates and subsequently re-activates the buffering action at the UPF and the UPF again receives downlink packets.
NOTE: For the notification about the downlink data delivery status "buffered" or "discarded" related to packets from a particular AF as part of the Nsmf_EventExposure service, it is expected that a PDR with a traffic filter identifying that AF as source and a Forwarding Action rule with action "buffer" is installed.
When the UP connection of the PDU Session is activated, the SMF updates the UPF of the change in buffering state. The buffered downlink packets, if any, are then forwarded to the (R)AN by the UPF.
If the UP connection of the PDU Session has been deactivated for a long time, the SMF may indicate the UPF to stop buffering for this PDU Session.
The SMF may indicate to the UPF to start or stop the buffering of uplink packets of an application associated to the PCC rule as described in clause 6.3.5 of TS 23.548 [130]. When the buffering of uplink packets is stopped the UPF shall forward all buffered uplink packets before it forwards any new uplink packets. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.19.3 Buffering at SMF | When the SMF supports buffering capability and the SMF decided to activate buffering in SMF for the PDU Session, the SMF shall inform the UPF to start forwarding the downlink packets towards the SMF.
When the UP connection of the PDU Session is activated, if there are buffered downlink packets available and their buffering duration has not expired, the SMF shall forward those packets to the UPF to relay them to the UE. These packets are then forwarded by the UPF to the (R)AN. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.20 SMF Pause of Charging | The SMF Pause of Charging functionality is supported with the purpose that the charging and usage monitoring data in the core network more accurately reflects the downlink traffic actually sent to the (R)AN. When the amount of downlink data incoming at the UPF for a PDU Session that is in deactivated state goes above a pre-configured threshold, the pause of charging functionality ensures that data that dropped in the core network is not included in charging and usage monitoring records.
The procedures for SMF Pause of Charging are described in TS 23.502 [3]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.21 Operator configurable UPF capabilities | UPF may support operator defined non-standardized feature(s) (such as hardware features (e.g. xPUs information (e.g. CPU/GPU information)), computing features (e.g. computing resource type, computing capability) and protection features (e.g. Firewall, DDoS)) or partially supported standardized feature(s). If the UPF supports such features, the UPF indicates the supported features to the SMF using the operator configurable UPF capabilities to the SMF via N4 association setup procedure or N4 association update procedure as described in clause 4.4.3 of TS 23.502 [3], or to the NRF via NF Service Registration procedure or NF service update procedure as described in clause 4.17 of TS 23.502 [3]. SMF can consider the operator configurable UPF capabilities for UPF selection as described in clause 6.3.3.
NOTE: The operator configurable UPF capabilities can be used for example for partially supported standardized feature(s), e.g. to identify the supported certain option(s) of a standard feature. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.22 Handling of Payload Headers | Support of Handling of Payload Headers is an optional UPF feature as defined in clause 5.6.17.
The SMF receives Header Handling Control information in a PCC rule (as described in clause 6.3.1 of TS 23.503 [45]), it forwards the Header Handling Control information to the UPF via N4 interactions. The SMF adds the Header Handling Control information relevant for the UL direction, if any, into the FAR that corresponds to the UL PDR of that PCC rule and the Header Handling Control information relevant for the DL direction, if any, into the FAR that corresponds to the DL PDR of that PCC rule.
If the Header Value parameter contains a reference to information to be added by SMF, the SMF shall overwrite the Header Value parameter with the indicated information of the corresponding PDU Session.
If SMF determines based on local configuration that it shall receive notifications related to the Handling of Payload Headers, it can modify the Header Handling Reporting of the header handling actions of interest by setting it to "yes" and by adding itself as an endpoint. In addition, the SMF shall add its Notification Target Address and a Notification Correlation ID to the Header Handling Reporting Endpoints sent to UPF.
When UPF receives a Header Handling Control Rule from SMF over N4 (see clause 5.8.5.6), it contains a Header Detection Reference (see clause 5.6.17.2) which points to a predefined configuration in UPF which includes the details of the protocol and possibly the message for which a header handling action shall be performed (e.g. HTTP, HTTP message). The interpretation of the Header Detection Reference is part of the SLA and thus, implementation specific.
The Header Handling Control Rule contains other explicit Header Handling Control information to be used for handling the traffic that matches the Header Detection Reference, see clause 5.6.17.2.
When the Header Handling Control Rule includes Header Handling Reporting information, UPF may send notifications related to the Handling of Payload Headers to SMF and/or NEF/AF. The enforcement of a requested action is a Header Handling event. If reporting has been requested, UPF reports the events of the actions executed. If Reporting suggestion information is received, the UPF performs as defined in clause 5.8.2.17. When One-time-report has been indicated for an action, the first occurrence of the action per packet flow is reported. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.2.23 N6 Delay Measurement and Reporting | The candidate UPF(s) may be configured by the SMF, as described in clause 4.4.3 of TS 23.502 [3], to measure the N6 delay for the connection between the UPF and measurement endpoint(s) in the DN (represented by one or more IP address(es)).
NOTE 1: The measurement endpoint in the DN used for delay measurements can be a single EAS IP address, for instance when the measurement endpoint is deployed within the same IP host as the EAS itself. Alternatively, the measurement endpoint used for delay measurements can be multiple EAS IP addresses within a certain IP address prefix/subnet, for instance when the measurement endpoint is deployed in a node such as a router or load balancer on path or close to the EAS. Hence the delay from the node to any of the EAS is considered as negligible.
NOTE 2: The N6 delay measurements are per measurement endpoint, hence are independent from any UE PDU Session.
AF provides the information to support N6 delay measurement via EAS Deployment Information Management as described in clause 6.2.3.4 of TS 23.548 [130]. SMF retrieves the EDI information to configure the candidate UPF(s) for the N6 delay measurement.
AF may trigger the N6 delay measurement by providing Indication of considering N6 delay measurement through AF influence as described in clause 5.6.7. The SMF may also trigger the N6 delay measurement based on local configuration after it is provisioned with the N6 delay measurement assistance information as part of EAS Deployment Information. The SMF requests the candidate UPF(s) (via N4 association procedures described in clause 4.4.3 of TS 23.502 [3]) to perform the N6 delay measurement between the UPF and measurement endpoint and to report the N6 delay measurement to SMF. The request includes the following information: measurement endpoint address (e.g., EAS IP address and optionally port number) together with a Network Instance for N6, measurement protocol (e.g. TWAMP (IETF RFC 5357 [211]), OWAMP (IETF RFC 4656 [212]), STAMP (IETF RFC 8762 [213]), or other protocols), protocol-specific configuration parameters. The UPF leverages the measurement protocol and Network Instance for N6 information to measure the N6 delay. Then, the candidate UPF(s) report the N6 delay measurement and the corresponding endpoint address to the SMF (via the N4 association report procedure described in clause 4.4.3 of TS 23.502 [3]. N6 delay measurement reporting is triggered based on the reporting frequency and/or reporting threshold provided as part of the configuration.
The SMF may (re)select the PSA UPF(s) or trigger EAS(es) (re)discovery by considering N6 delay measurement result as described in clause 6.2.3.2 of TS 23.548 [130]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.3 Explicit Buffer Management (moved) | The Explicit Buffer Management is described in clause 5.8.2.19. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.4 SMF Pause of Charging (moved) | The SMF Pause of Charging is described in clause 5.8.2.20. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5 Parameters for N4 session management | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.1 General | These parameters are used by SMF to control the functionality of the UPF as well as to inform SMF about events occurring at the UPF.
The N4 session management procedures defined in clause 4.4.1 of TS 23.502 [3] will use the relevant parameters in the same way for all N4 reference points: the N4 Session Establishment procedure as well as the N4 Session Modification procedure provide the control parameters to the UPF, the N4 Session Release procedure removes all control parameters related to an N4 session and the N4 Session Level Reporting procedure informs the SMF about events related to the PDU Session that are detected by the UPF.
The parameters over N4 reference point provided from SMF to UPF comprises an N4 Session ID and may also contain:
- Packet Detection Rules (PDR) that contain information to classify traffic (PDU(s)) arriving at the UPF;
- Forwarding Action Rules (FAR) that contain information on whether forwarding, dropping or buffering is to be applied to a traffic identified by PDR(s);
- Multi-Access Rules (MAR) that contain information on how to handle traffic steering, switching and splitting for a MA PDU Session;
- Usage Reporting Rules (URR) contains information that defines how traffic identified by PDR(s) shall be accounted as well as how a certain measurement shall be reported;
- QoS Enforcement Rules (QER), that contain information related to QoS enforcement of traffic identified by PDR(s);
- Session Reporting Rules (SRR) that contain information to request the UP function to detect and report events for a PDU session that are not related to specific PDRs of the PDU session or that are not related to traffic usage measurement.
- Trace Requirements;
- Port Management Information Container in 5GS;
- Bridge/Router Information.
The N4 Session ID is assigned by the SMF and uniquely identifies an N4 session.
If the UPF indicated support of Trace, the SMF may activate a trace session during a N4 Session Establishment or a N4 Session Modification procedure. In that case it provides Trace Requirements to the UPF. The SMF may deactivate an on-going trace session using a N4 Session Modification procedure. There shall be at most one trace session activated per N4 Session at a time.
For the MA PDU Session, the SMF may add an additional access tunnel information during an N4 Session Modification procedure by updating MAR with addition of an FAR ID which refers to an FAR containing the additional access tunnel information for the MA PDU session for traffic steering in the UPF. For the MA PDU Session, the SMF may request Access Availability report per N4 Session, during N4 Session Establishment procedure or N4 Session Modification procedure.
A N4 Session may be used to control both UPF and NW-TT behaviour in the UPF. A N4 session support and enable exchange of bridge/router configuration between the SMF and the UPF:
- Information that the SMF needs for bridge/router management (clause 5.8.5.9);
- Information that 5GS transparently relays between the TSN AF or TSCTSF and the NW-TT: transparent Port Management Information Container along with the associated NW-TT port number.
- Information that 5GS transparently relays between the TSN AF or TSCTSF and the NW-TT: transparent user plane node Management Information Container (clause 5.8.5.14).
When a N4 Session related with bridge/router management is established, the UPF allocates a dedicated port number for the PDU Session. The UPF then provides to the SMF following configuration parameters for the N4 Session:
- port number.
- user-plane node ID.
To support TSN, the user-plane node ID is Bridge ID. To support integration with IETF DetNet, the user-plane node ID can be Router ID. The User Plane Node ID may be pre-configured in the UPF based on deployment.
After the N4 session has been established, the SMF and UPF may at any time exchange transparent user plane node and Port Management Information Container over a N4 session. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.2 N4 Session Context | N4 Session Context is identified by an N4 Session ID. An N4 Session Context is generated by SMF and UPF respectively to store the parameters related to an N4 session, including the N4 session ID and following information (see TS 29.244 [65] for an exhaustive list):
1) general session related parameters such as S-NSSAI, PDU Session Type, Trace Information, APN/DNN, ATSSS Control Information;
2) the PDRs, URRs, QERs, BAR(s), FARs, MARs used for this N4 session;
3) parameters sent to support UPF statistics.
The UPF may use parameters listed above in bullets 1) (e.g. S-NSSAI) and 2) (e.g. Network Instance in PDR/FAR(s)) for determining internal UPF resources. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.3 Packet Detection Rule | The following table describes the Packet Detection Rule (PDR) containing information required to classify a packet arriving at the UPF. Every PDR is used to detect packets in a certain transmission direction, e.g. UL direction or DL direction.
Table 5.8.5.3-1: Attributes within Packet Detection Rule
Attribute
Description
Comment
N4 Session ID
Identifies the N4 session associated to this PDR. NOTE 5.
Rule ID
Unique identifier to identify this rule.
Precedence
Determines the order, in which the detection information of all rules is applied.
Packet
Source interface
Contains the values "access side", "core side", "SMF", "N6-LAN", "5G VN internal".
Combination of UE IP address (together with Network instance, if necessary), CN tunnel info,
Detection
UE IP address
One IPv4 address and/or one IPv6 prefix with prefix length (NOTE 3).
packet filter set, application identifier, Ethernet PDU Session
Information.
NOTE 4.
Network instance (NOTE 1)
Identifies the Network instance associated with the incoming packet.
Information and QFI are used for traffic detection.
Source interface identifies the
CN tunnel info
CN tunnel info on N3, N9 interfaces, i.e. F-TEID.
interface for incoming packets
Packet Filter Set
Details see clause 5.7.6.
where the PDR applies, e.g. from access side (i.e. up-link),
Application identifier
from core side (i.e. down-link),
QoS Flow ID
Contains the value of 5QI or non-standardized QFI.
from SMF, from N6-LAN (i.e. the
Ethernet PDU Session Information
Refers to all the (DL) Ethernet packets matching an Ethernet PDU session, as further described in clause 5.6.10.2 and in TS 29.244 [65].
DN), or from "5G VN internal" (i.e. local switch).
Framed Route Information
Refers to Framed Routes defined in clause 5.6.14.
Details like all the combination possibilities on N3, N9 interfaces are left for stage 3 decision.
FQDN Filter for DNS Query
Contains one or more FQDN, FQDN range and/or any FQDN.
The FQDN or FQDN range only used for detection of plain DNS Query message (i.e. not subject to ciphering). The usage is described in TS 23.548 [130].
Protocol Description
Indicates service protocol used by the flow (NOTE 8), (NOTE 9).
Expedited Transfer Indication
Contains the value of the "Expedited Transfer Indication" for the downlink traffic. Can be set to TRUE or FALSE (NOTE 10).
Packet replication and detection carry on information
Packet replication skip information NOTE 7
Contains UE address indication or N19/N6 indication. If the packet matches the packet replication skip information, i.e. source address of the packet is the UE address or the packet has been received on the interface in the packet replication skip information, the UP function neither creates a copy of the packet nor applies the corresponding processing (i.e. FAR, QER, URR). Otherwise the UPF performs a copy and applies the corresponding processing (i.e. FAR, QER, URR).
NOTE 6
Carry on indication
Instructs the UP function to continue the packet detection process, i.e. lookup of the other PDRs.
Outer header removal
Instructs the UP function to remove one or more outer header(s) (e.g. IP+UDP+GTP, IP + possibly UDP, VLAN tag), from the incoming packet.
Any extension header shall be stored for this packet.
Forwarding Action Rule ID (NOTE 2)
The Forwarding Action Rule ID identifies a forwarding action that has to be applied.
Multi-Access Rule ID (NOTE 2)
The Multi-Access Rule ID identifies an action to be applied for handling forwarding for a MA PDU Session.
List of Usage Reporting Rule ID(s)
Every Usage Reporting Rule ID identifies a measurement action that has to be applied.
List of QoS Enforcement Rule ID(s)
Every QoS Enforcement Rule ID identifies a QoS enforcement action that has to be applied.
NOTE 1: Needed e.g. if:
- UPF supports multiple DNN with overlapping IP addresses;
- UPF is connected to other UPF or AN node in different IP domains.
- UPF "local switch", N6-based forwarding and N19 forwarding is used for different 5G LAN groups.
- UPF "local switch" may be used for DNN/S-NSSAI dedicated for PIN.
NOTE 2: Either a FAR ID or a MAR ID is included, not both.
NOTE 3: The SMF may provide an indication asking the UPF to allocate one IPv4 address and/or IPv6 prefix. When asking to provide an IPv6 Prefix the SMF provides also an IPv6 prefix length.
NOTE 4: When in the architecture defined in clause 5.34, a PDR is sent over N16a from SMF to I-SMF, the Packet Detection Information may indicate that CN tunnel info is to be locally determined. This is further defined in clause 5.34.6.
NOTE 5: In the architecture defined in clause 5.34, the rules exchanged between I-SMF and SMF are not associated with a N4 Session ID but are associated with a N16a association.
NOTE 6: Needed in the case of support for broadcast/multicast traffic forwarding using packet replication with SMF-provided PDRs and FARs as described in clause 5.8.2.13.3.2.
NOTE 7: Needed in the case of packet replication with SMF-provided PDRs and FARs as described in clause 5.8.2.13.3.2, to prevent UPF from sending the broadcast/multicast packets back to the source UE or source N19/N6.
NOTE 8: Not for PDR matching. In the case of unencrypted traffic, it may be provided to assist PDU Set identification when PDU Set Identification and marking applies to the PDR and/or to assist identification of the last packet of the Data burst in downlink when End of Data Burst identification and marking in downlink applies to the PDR. It may assist determination of the Data Burst Size of the data burst when Data Burst Size determination and marking in downlink applies to the PDR. See TS 26.522 [179]. It may assist determination of the Time to Next Burst when time to next data burst determination and marking in downlink applies to the PDR. See TS 26.522 [179].
NOTE 9: Not for PDR matching. In the case of end-to-end encrypted traffic, it may be provided to indicate how to retrieve media related information as specified in clause 5.37.9.
NOTE 10: For PDR matching but only applicable for a PDR with Source interface "core side". Needed in the case of Expedited Data Transfer with reflective QoS as described in clause 5.37.10.3. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.4 QoS Enforcement Rule | The following table describes the QoS Enforcement Rule (QER) that defines how a packet shall be treated in terms of bit rate limitation and packet marking for QoS purposes. All Packet Detection Rules that refer to the same QER share the same QoS resources, e.g. MFBR.
Table 5.8.5.4-1: Attributes within QoS Enforcement Rule
Attribute
Description
Comment
N4 Session ID
Identifies the N4 session associated to this QER
Rule ID
Unique identifier to identify this information.
QoS Enforcement Rule correlation ID (NOTE 1)
An identity allowing the UP function to correlate multiple Sessions for the same UE and APN.
Is used to correlate QoS Enforcement Rules for APN-AMBR enforcement.
Gate status UL/DL
Instructs the UP function to let the flow pass or to block the flow.
Values are: open, close, close after measurement report (for termination action "discard").
Maximum bitrate
The uplink/downlink maximum bitrate to be enforced for the packets.
This field may e.g. contain any one of:
- APN-AMBR (for a QER that is referenced by all relevant Packet Detection Rules of all PDN Connections to an APN) (NOTE 1).
- Session-AMBR (for a QER that is referenced by all relevant Packet Detection Rules of the PDU Session)
- QoS Flow MBR (for a QER that is referenced by all Packet Detection Rules of a QoS Flow)
- SDF MBR (for a QER that is referenced by the uplink/downlink Packet Detection Rule of a SDF)
- Bearer MBR (for a QER that is referenced by all relevant Packet Detection Rules of a bearer) (NOTE 1).
Guaranteed bitrate
The uplink/downlink guaranteed bitrate authorized for the packets.
This field contains:
- QoS Flow GBR (for a QER that is referenced by all Packet Detection Rules of a QoS Flow)
- Bearer GBR (for a QER that is referenced by all relevant Packet Detection Rules of a bearer) (NOTE 1).
Averaging window
The time duration over which the Maximum and Guaranteed bitrate shall be calculated.
This is for counting the packets received during the time duration.
Down-link flow level marking
Flow level packet marking in the downlink.
For UPF, this is for controlling the setting of the RQI in the encapsulation header as described in clause 5.7.5.3.
QoS Flow ID
QoS Flow ID to be inserted by the UPF.
The UPF inserts the QFI value in the tunnel header of outgoing packets.
Paging Policy Indicator
Indicates the PPI value the UPF is required to insert in outgoing packets (see clause 5.4.3.2).
PPI applies only for DL traffic. The UPF inserts the PPI in the outer header of outgoing PDU.
Packet rate (NOTE 1)
Number of packets per time interval to be enforced.
This field contains any one of:
- downlink packet rate for Serving PLMN Rate Control (the QER is referenced by all PDRs of the UE belonging to PDN connections using CIoT EPS Optimisations as described in TS 23.401 [26]).
- uplink/downlink packet rate for APN Rate Control (the QER is referenced by all PDRs of the UE belonging to PDN connections to the same APN using CIoT EPS Optimisations as described in TS 23.401 [26]).
End of Data Burst Marking Indication
Indicates to the UPF to provide an End of Data Burst indication of the last PDU of a Data burst to the NG-RAN over GTP-U
NG-RAN can configure UE power management schemes like connected mode DRX when UPF provides an indication of the End of Data Burst, see clause 5.37.8.3.
Data Burst Size Marking Indication
Indicates to the UPF to insert the Data Burst Size of the data burst to the GTP-U header of the first PDUs of the data burst.
NG-RAN may use the received Data Burst Size to assist radio resource management, see clause 5.37.10.1.
Time to Next Burst Marking Indication
Indicates to the UPF to insert the Time to Next Burst to the GTP-U header if included in an N6 RTP Header Extension/transport protocol header.
NG-RAN may use the received Time to Next Burst to assist network scheduling in downlink, as described in clause 5.37.10.2.
PDU Set Information marking Indicator
Indicates the UPF to insert PDU Set Information related to packets belonging to a PDU Set into GTP-U header.
UPF identifies PDU Sets in DL traffic and forwards PDU Set related information of each PDU to the 5G-AN over GTP-U, as described in clause 5.37.5.
ECN marking for L4S indicator (NOTE 2)
Indicates the UPF to perform ECN marking for L4S for the corresponding QoS Flow.
UPF uses information sent by NG-RAN in GTP-U header extension to perform ECN marking for L4S for the corresponding direction.
NOTE 1: This parameter is only used for interworking with EPC.
NOTE 2: This parameter is only used for 3GPP access and is not applicable for non-3GPP access. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.5 Usage Reporting Rule | The following table describes the Usage Reporting Rule (URR) that defines how a packet shall be accounted as well as when and how to report the measurements.
Table 5.8.5.5-1: Attributes within Usage Reporting Rule
Attribute
Description
Comment
N4 Session ID
Identifies the N4 session associated to this URR
Rule ID
Unique identifier to identify this information.
Used by UPF when reporting usage.
Reporting triggers
One or multiple of the events can be activated for the generation and reporting of the usage report.
Applicable events include:
- Start/stop of traffic detection with/without application instance identifier and deduced SDF filter reporting; Deletion of last PDR for a URR; Periodic measurement threshold reached; Volume/Time/Event measurement threshold reached; Immediate report requested; Measurement of incoming UL traffic; Measurement of discarded DL traffic; MAC address reporting in the UL traffic; unknown destination MAC/IP address; end marker packet has been received.
Periodic measurement threshold
Defines the point in time for sending a periodic report for this URR (e.g. timeofday).
This allows generation of periodic usage report for e.g. offline charging.
It can also be used for realizing the Monitoring time of the usage monitoring feature.
It can also be used for realizing the Quota-Idle-Timeout, i.e. to enable the CP function to check whether any traffic has passed during this time.
Volume measurement threshold
Value in terms of uplink and/or downlink and/or total byte-count when the measurement report is to be generated.
Time measurement threshold
Value in terms of the time duration (e.g. in seconds) when the measurement report is to be generated.
Event measurement threshold
Number of events (identified according to a locally configured policy) after which the measurement report is to be generated.
Inactivity detection time
Defines the period of time after which the time measurement shall stop, if no packets are received.
Timer corresponding to this duration is restarted at the end of each transmitted packet.
Event based reporting
Points to a locally configured policy which is identifies event(s) trigger for generating usage report.
Linked URR ID(s)
Points to one or more other URR ID.
This enables the generation of a combined Usage Report for this and other URRs by triggering their reporting. See clause 5.2.2.4, TS 29.244 [65].
Measurement Method
Indicates the method for measuring the network resources usage, i.e. the data volume, duration, combined volume/duration, or event.
Measurement information
Indicates specific conditions to be applied for measurements
It is used to request:
- measurement before QoS enforcement and/or
- to pause or set to active a measurement as for the Pause of charging described in clause 4.4.4 and clause 4.23.14 of TS 23.502 [3] and/or
- to request reduced reporting for application start/stop events. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.6 Forwarding Action Rule | The following table describes the Forwarding Action Rule (FAR) that defines how a packet shall be buffered, dropped or forwarded, including packet encapsulation/decapsulation and forwarding destination.
Table 5.8.5.6-1: Attributes within Forwarding Action Rule
Attribute
Description
Comment
N4 Session ID
Identifies the N4 session associated to this FAR.
NOTE 9.
Rule ID
Unique identifier to identify this information.
Action
Identifies the action to apply to the packet
Indicates whether the packet is to be forwarded, duplicated, dropped or buffered.
When action indicates forwarding or duplicating, a number of additional attributes are included in the FAR.
For buffering action, a Buffer Action Rule is also included and the action can also indicate that a notification of the first buffered and/or a notification of first discarded packet is requested (see clause 5.8.3.2).
For drop action, a notification of the discarded packet may be requested (see clause 5.8.3.2).
Network instance
(NOTE 2)
Identifies the Network instance associated with the outgoing packet (NOTE 1).
NOTE 8.
Destination interface
(NOTE 3)
(NOTE 7)
Contains the values "access side", "core side", "SMF", "N6-LAN", "5G VN internal".
Identifies the interface for outgoing packets towards the access side (i.e. down-link), the core side (i.e. up-link), the SMF, the N6-LAN (i.e. the DN), or to 5G VN internal (i.e. local switch).
Outer header creation
(NOTE 3)
Instructs the UP function to add an outer header (e.g. IP+UDP+GTP, VLAN tag), IP + possibly UDP to the outgoing packet.
Contains the CN tunnel info, N6 tunnel info or AN tunnel info of peer entity (e.g. NG-RAN, another UPF, SMF, local access to a DN represented by a DNAI) (NOTE 8).
Any extension header stored for this packet shall be added.
The time stamps should be added in the GTP-U header if QoS Monitoring for packet delay is enabled for the traffic corresponding to the PDR(s).
Send end marker packet(s)
(NOTE 2)
Instructs the UPF to construct end marker packet(s) and send them out as described in clause 5.8.1.
This parameter should be sent together with the "outer header creation" parameter of the new CN tunnel info.
Transport level marking
(NOTE 3)
Transport level packet marking in the uplink and downlink, e.g. setting the DiffServ Code Point. For the downlink direction, when the network is configured to take the PDU Set Importance into account for transport level marking, contains a list of Transport level marking values, each associated with one or more PDU Set Importance values, based on which the UPF performs PDU Set Importance based transport level packet marking (instead of Transport level marking).
NOTE 8.
Forwarding policy
(NOTE 3)
Reference to a preconfigured traffic steering policy or http redirection (NOTE 4).
The Forwarding policy refers to a preconfigured forwarding behaviour in UPF, which may be related to:
- N6-LAN steering to steer the subscriber's traffic to the appropriate N6 Service Functions deployed by the operator;
- local N6 steering to enable traffic steering in the local access to the DN according to the routing information provided by an AF as described in clause 5.6.7;
- a Redirect Destination and values for the forwarding behaviour (always, after measurement report (for termination action "redirect")).
Metadata
(NOTE 10)
Metadata the UPF needs to add to traffic sent over a SFC.
The metadata information is associated with a TSP ID related to N6-LAN steering.
Request for Proxying in UPF
Indicates that the UPF shall perform ARP proxying and / or IPv6 Neighbour Solicitation Proxying as specified in clause 5.6.10.2.
Applies to the Ethernet PDU Session type.
On-path N6 connection information
Indicates to establish a connection to get media related information and contains the signalling method and the AS proxy address, see clause 5.37.9 (NOTE 13).
Applies when connect-UDP protocol is used.
Container for header enrichment
(NOTE 2)
Contains information to be used by the UPF for header enrichment.
Only relevant for the uplink direction.
Buffering Action Rule
(NOTE 5)
Reference to a Buffering Action Rule ID defining the buffering instructions to be applied by the UPF
(NOTE 6)
Header Handling Control Rule (see clause 5.6.17) (NOTE 11)
Header Detection Reference
A reference to a UPF configuration which defines how to detect the protocol or the message in a protocol for which to perform the header handling actions.
Header Detection Support Information
Any dynamic information provided by the AF which is required for the detection of the headers and cannot be preconfigured for the Header handling Detection Reference.
Header Handling Reporting Endpoints
List of notifications endpoints, i.e. per notification endpoint a Notification Target Address and a Notification Correlation ID.
Header Handling Control Reference
A reference to a Header Handling Action related information pre-configured in the UPF.
Header Handling Action
(NOTE 12)
Indicates the header handling action to be performed on a specific header field
Possible values: Detect, Remove, Replace, Insert.
Header Information
(NOTE 12)
A reference to a UPF configuration which defines how to identify a specific header field for which to perform the header handling action.
Header Value
(NOTE 12)
A string describing the value of the specific header field.
Mandatory for Replace action, optional for Remove, Insert and Detect action.
Header Handling Condition
(NOTE 12)
Indicates the condition for performing the header handling action.
Possible values: first match, every match.
Header Handling Reporting
(NOTE 12)
Indicates whether reporting is requested for the performed Header Handling Action and the notification endpoint(s).
Possible values: yes/no; if yes, one or more of the notification endpoints.
Optionally, to reduce signalling, it may include Reporting suggestion information and One time Report indication.
NOTE 1: Needed e.g. if:
- UPF supports multiple DNN with overlapping IP addresses;
- UPF is connected to other UPF or NG-RAN node in different IP domains;
- UPF "local switch" and N19 forwarding is used for different 5G LAN groups.
NOTE 2: These attributes are required for FAR action set to forwarding.
NOTE 3: These attributes are required for FAR action set to forwarding or duplicating.
NOTE 4: The TSP ID is preconfigured in the SMF and used to determine the Forwarding Policy included in the FAR according to the description in clause 5.6.7 and clause 6.1.3.14 of TS 23.503 [45] for local N6 steering and in clause 5.6.16 and clause 6.1.3.14 of TS 23.503 [45] for N6-LAN steering. The Forwarding Policy action is enforced before the Outer header creation actions.
NOTE 5: This attribute is present for FAR action set to buffering.
NOTE 6: The buffering action rule is created by the SMF and associated with the FAR in order to apply a specific buffering behaviour for UL/DL packets requested to be buffered, as described in clause 5.8.3 and clause 5.2.4 of TS 29.244 [65].
NOTE 7: The use of "5G VN internal" instructs the UPF to send the packet back for another round of ingress processing using the active PDRs pertaining to another N4 session of the same 5G VN group.
NOTE 8: When in architectures defined in clause 5.34, a FAR is sent over N16a from SMF to I-SMF, the FAR sent by the SMF may indicate that the I-SMF is to locally determine the value of this attribute in order to build the N4 FAR rule sent to the actual UPF controlled by the I-SMF. This is further defined in clause 5.34.6.
NOTE 9: In the architecture defined in clause 5.34, the rules exchanged between I-SMF and SMF are not associated with a N4 Session ID but are associated with a N16a association.
NOTE 10: The use of Metadata is described in clause 5.6.16. How the UPF transforms the Metadata into actual information sent with the traffic (e.g. in the encapsulation header) is based on local policies related with the Forwarding Policy and not specified.
NOTE 11: More detailed description of each of the Header Handling Control Rule parameters can be found in clause 5.6.17.2 which describes the corresponding AF provided parameters in the Header Handling Control information.
NOTE 12: These parameters are provided together to request a Header Handling Action. Multiple sets of these parameters (and thus multiple header handling actions) can be provided. One or more of these parameters can be provided to overwrite Header Handling Action related information pre-configured in the UPF as per the Header Handling Control Reference.
NOTE 13: To be able to provide the media related information to the UPF, a close cooperation between the AS and the Proxy is assumed. Such cooperation is out of the scope of 3GPP. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.7 Usage Report generated by UPF | The UPF sends the Usage Report to inform the SMF about the measurement of an active URR or about the detection of application traffic of an active Packet Detection Rule. For each URR, the Usage Report may be generated repeatedly, i.e. as long as any one of the valid event triggers applies. A final Usage Report is sent for a URR when it is no longer active, i.e. either the URR is removed or all the references to this URR in any of the Packet Detection Rules belonging to the N4 session.
The following attributes can be included:
Table 5.8.5.7-1: Attributes within Usage Report
Attribute
Description
Comment
N4 Session ID
Uniquely identifies a session.
Identifies the N4 session associated to this Usage Report
Rule ID
Uniquely identifies the Packet Detection Rule or Usage Reporting Rule within a session which triggered the report.
Packet Detection Rule is only indicated when Reporting trigger is Start/stop of traffic detection.
Usage Reporting Rule is indicated for all other Reporting triggers.
Reporting trigger
Identifies the trigger for the usage report.
Applicable values are:
Start/stop of traffic detection with/without application instance identifier and deduced SDF filter reporting; Deletion of last PDR for a URR; Periodic measurement threshold reached; Volume/Time/Event measurement threshold reached; Immediate report requested; Measurement of incoming UL traffic; Measurement of discarded DL traffic; MAC address reporting in the UL traffic; reporting of unknown destination MAC/IP address; end marker packet has been received.
Start time
Provides the timestamp, in terms of absolute time, when the collection of the information provided within Usage-Information is started.
Not sent when Reporting trigger is Start/stop of traffic detection.
End time
Provides the timestamp, in terms of absolute time, when the information provided within Usage-Information is generated.
Not sent when Reporting trigger is Start/stop of traffic detection.
Measurement information
Defines the measured volume/time/events for this URR.
For details refer to clause 7.5.8.3 of TS 29.244 [65].
Other information
Other events/information, e.g. related to reporting of UE MAC addresses.
For details refer to clause 7.5.8.3 of TS 29.244 [65]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.8 Multi-Access Rule | The following table describes the Multi-Access Rule (MAR) that includes the association to the two FARs for both 3GPP access and non-3GPP access in the case of supporting ATSSS.
Table 5.8.5.8-1: Attributes within Multi-Access Rule
Attribute
Description
Comment
N4 Session ID
Identifies the N4 session associated to this MAR.
Rule ID
Unique identifier to identify this rule.
Steering functionality
(NOTE 5)
Indicates the applicable traffic steering functionality:
Values "MPTCP functionality", "ATSSS-LL functionality", "MPQUIC-UDP functionality", "MPQUIC-IP functionality", "MPQUIC-E functionality".
Transport Mode
Identifies the transport mode (see clause 5.32.6.2.2.1) that should be used for the matching traffic, when the Steering functionality is the MPQUIC-UDP functionality, the MPQUIC-IP functionality, or the MPQUIC-E functionality.
The Transport Mode shall be included only when the Steering Functionality is the MPQUIC-UDP functionality, the MPQUIC-IP functionality or the MPQUIC-E functionality. In all other cases, the Transport Mode shall not be included.
Steering mode
(NOTE 5)
Values "Active-Standby", "Smallest Delay", "Load Balancing", or "Priority-based" or "Redundant".
Steering Mode Indicator
(NOTE 4)
Indicates either autonomous load-balance operation or UE-assistance operation if steering mode is set to "Load Balancing".
Threshold values
(NOTE 3, NOTE 4)
A Maximum RTT and/or a Maximum Packet Loss Rate
The Threshold Values are applied by UPF as described in clause 5.32.8.
Per-Access Forwarding
Forwarding Action Rule ID
The Forwarding Action Rule ID identifies a forwarding action that has to be applied.
Action information
Weight
Identifies the weight for the FAR if steering mode is "Load Balancing"
The weights for all FARs need to sum up to 100
(NOTE 1)
(NOTE 2)
Priority
Values "Active or Standby" or "High or Low" for the FAR
"Active or Standby" for "Active-Standby" steering mode and "High or Low" for "Priority-based" steering mode
List of Usage Reporting Rule ID(s)
Every Usage Reporting Rule ID identifies a measurement action that has to be applied.
This enables the SMF to request separate usage reports for different FARs (i.e. different accesses)
NOTE 1: The Per-Access Forwarding Action information is provided per access type (i.e. 3GPP access or Non-3GPP access).
NOTE 2: The Weight is treated as the default percentages if the Autonomous operation is allowed for the "Load Balancing" steering mode.
NOTE 3: The Threshold Values may be provided when the Steering Mode is Priority-based, or when the Steering Mode is Load-Balancing with fixed split percentages or when the Steering Mode is "Redundant". If the Steering Mode is "Redundant", either a Maximum RTT or a Maximum Packet Loss Rate may be provided, but not both.
NOTE 4: The Steering Mode Indicator and the Threshold Values shall not be provided together.
NOTE 5: The Steering functionality "ATSSS-LL functionality" shall not be provided together with Steering Mode "Redundant". |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.9 Bridge/Router Information | The following table describes the User plane node Information (UI) that includes the information required to configure a 5GS logical bridge/router for TSC or Deterministic Networking PDU Sessions.
Table 5.8.5.9-1: User plane node Information
Attribute
Description
Comment
Port Number
Port Number allocated by the node for a given PDU Session
User plane node ID
Bridge identifier of the 5GS TSN bridge, or user-plane node ID. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.10 Void | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.11 Session Reporting Rule | The following table describes the Session Reporting Rule (SRR) that defines the detection and reporting events that the UPF shall report, that are not related to specific PDRs of the PDU Session, as follows:
- Per QoS Flow per UE QoS Monitoring Report, as specified in clause 5.33.3.2.
- Change of 3GPP or non-3GPP access availability, for an MA PDU session.
- Per QoS Flow N6 Traffic Parameter Measurement Report.
Table 5.8.5.11-1: Attributes within Session Reporting Rule
Attribute
Description
Comment
N4 Session ID
Identifies the N4 session associated to this SRR.
Rule ID
Unique identifier to identify this information.
Used by UPF when reporting.
QoS Monitoring per QoS Flow Control Information
Indicates the UPF to apply perform the QoS Monitoring report for one or more QoS Flows.
The IE is defined in clause 7.5.2.9 of the TS 29.244 [65].
See NOTE 1.
Access Availability Control Information
Indicates the UPF to report when an access type becomes available or unavailable for an MA PDU Session.
The IE is defined in clause 7.5.2.9 of TS 29.244 [65].
N6 Traffic Parameter Measurement Control Information
Indicates the UPF to report N6 Traffic parameter measurements for one QoS Flow, e.g. a measurement of N6 jitter range for a DL Periodicity and conditionally, a measurement of the UL/DL periodicity.
May indicate the DL Periodicity (See NOTE 2).
The IE is defined in clause 7.5.2.9 of TS 29.244 [65].
See NOTE 2.
NOTE 1: The QoS Monitoring per QoS Flow Control Information may contain an Indication of local direct event notification and. The Indication of local event notification includes a Notification Target Address (the details are described in clause 5.8.2.18) that identifies the recipient of the information being notified by the UPF (Local NEF/AF). The Indication of local direct event notification also indicates that the UPF reports the information to the NF indicated by the Target of reporting via Nupf_EventExposure_Notify service operation.
NOTE 2: The DL Periodicity is provided by the SMF in the N6 Traffic Parameters Measurement Control Information when the DL Periodicity is received from the PCF. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.12 Session reporting generated by UPF | The UPF sends the session report to inform the SMF the detected events for a PDU Session that are related to an SRR. The UPF may support notification to the AF possibly via local NEF as described in clause 6.4 of TS 23.548 [130].
Table 5.8.5.12-1: Attributes within Session Reporting
Attribute
Description
Comment
N4 Session ID
Identifies the N4 session associated to the SRR which triggered the report.
Rule ID
Unique identifier to identify the Session Reporting Rule within a session which triggered the report.
Used by UPF when reporting.
QoS Monitoring Report
Indicates the QoS Monitoring result for one or more QoS Flows.
The IE is defined in clause 7.5.8.6 of TS 29.244 [65].
Access Availability Report
Indicates the change of 3GPP or non-3GPP access availability, for an MA PDU session.
The IE is defined in clause 7.5.8.6 of TS 29.244 [65].
N6 Traffic Parameter Measurement Report
Indicates the N6 Traffic Parameter measurement result for one QoS Flow, e.g. a measurement of N6 jitter range associated with a DL Periodicity and conditionally, a measurement of the UL/DL periodicity.
The IE is defined in clause 7.5.8.6 of TS 29.244 [65]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.13 Void | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.14 TSC Management Information | The following table describes the TSC Management Information Container (TSC MIC) that includes UMIC, PMIC and the associated NW-TT port number.
The SMF may include the notification target address for PMIC/UMIC UPF event provided by the PCF in the TSC Management Information sent to UPF if the UPF supports the related redirect reporting via Nupf. If the notification target address for PMIC/UMIC UPF event is provided by the SMF, the UPF may directly report TSC management information to the TSNAF or TSCTSF using Nupf_EventExposure_Notify service operation described in clause 7.2.29.
Table 5.8.5.14-1: TSC Management Information Container
Attribute
Description
Comment
User plane node Management Information Container
5GS TSN Bridge or Router information exchanged transparently between NW-TT and TSN AF or TSCTSF via 5GS (as in Table K.1-2).
Port Management Information Container
Information exchanged transparently between NW-TT and TSN AF or TSCTSF via 5GS (as in Table K.1-1).
NW-TT Port Number
NW-TT Port Number related to the PMIC.
Included when the PMIC information is present.
Notification Target Address for PMIC/UMIC UPF event (+ Notification Correlation ID) for PMIC/UMIC UPF event
Identifies the recipient of the information being notified by the UPF (TSNAF/TSCTSF). |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.8.5.15 Downlink Data Report generated by UPF | The UPF sends the Downlink Data Report to inform the SMF about the events related to receiving or discarding of downlink packets. The SMF controls this type of UPF report by providing instructions in the Buffer Action Rule of a FAR.
Following attributes can be included:
Table 5.8.5.15-1: Attributes within Downlink Data Report
Attribute
Description
Comment
N4 Session ID
Uniquely identifies a session.
Identifies the N4 Session associated to this Usage Report
Rule ID
Uniquely identifies the Packet Detection Rule which triggered the report.
Downlink Data Service Information
Indicates that the first downlink packet has been received for a QoS Flow at the UPF by reporting the QFI, if it is available. For the IP PDU Session Type, the DSCP in TOS (IPv4) / TC (IPv6) value from the IP header of the downlink packet will also be reported.
This is used for downlink data notification related to QoS Flows.
Downlink Data Status
Indicates that the first downlink packet has been buffered or discarded for a service data flow at the UPF.
This is used for downlink data delivery status notification related to individual services. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.9 Identifiers | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.9.1 General | Each subscriber in the 5G System shall be allocated one 5G Subscription Permanent Identifier (SUPI) for use within the 3GPP system. The 5G System supports identification of subscriptions independently of identification of the user equipment. Each UE accessing the 5G System shall be assigned a Permanent Equipment Identifier (PEI).
The 5G System supports allocation of a temporary identifier (5G-GUTI) in order to support user confidentiality protection. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.9.2 Subscription Permanent Identifier | A globally unique 5G Subscription Permanent Identifier (SUPI) shall be allocated to each subscriber in the 5G System and provisioned in the UDM/UDR. The SUPI is used only inside 3GPP system and its privacy is specified in TS 33.501 [29].
The SUPI may contain:
- an IMSI as defined in TS 23.003 [19], or
- a network-specific identifier, used for private networks as defined in TS 22.261 [2].
- a GLI and an operator identifier of the 5GC operator, used for supporting FN-BRGs, as further described in TS 23.316 [84].
- a GCI and an operator identifier of the 5GC operator, used for supporting FN-CRGs and 5G-CRG, as further described in TS 23.316 [84].
A SUPI containing a network-specific identifier shall take the form of a Network Access Identifier (NAI) using the NAI RFC 7542 [20] based user identification as defined in TS 23.003 [19].
When UE needs to indicate its SUPI to the network (e.g. as part of the Registration procedure), the UE provides the SUPI in concealed form as defined in TS 23.003 [19].
In order to enable roaming scenarios, the SUPI shall contain the address of the home network (e.g. the MCC and MNC in the case of an IMSI based SUPI).
For interworking with the EPC, the SUPI allocated to the 3GPP UE shall always be based on an IMSI to enable the UE to present an IMSI to the EPC.
The usage of SUPI for W-5GAN is further specified in TS 23.316 [84].
5.9.2a Subscription Concealed Identifier
The Subscription Concealed Identifier (SUCI) is a privacy preserving identifier containing the concealed SUPI. It is specified in TS 33.501 [29].
The usage of SUCI for W-5GAN access is further specified in TS 23.316 [84]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.9.3 Permanent Equipment Identifier | A Permanent Equipment Identifier (PEI) is defined for the 3GPP UE accessing the 5G System.
The PEI can assume different formats for different UE types and use cases. The UE shall present the PEI to the network together with an indication of the PEI format being used.
If the UE supports at least one 3GPP access technology (i.e. NG-RAN, E-UTRAN, UTRAN or GERAN), the UE must be allocated a PEI in the IMEI or IMEISV format.
If a UE has registered with a network by using a network subscription and a PEI of the UE, then the UE shall keep the PEI to be used with the network subscription and shall not use that PEI with another network subscription while the UE is in registered state in the network.
In the scope of this release, the PEI may be one of the following:
- for UEs that support at least one 3GPP access technology, an IMEI or IMEISV, as defined in TS 23.003 [19];
- PEI used in the case of W-5GAN access as further specified in TS 23.316 [84].
- for UEs not supporting any 3GPP access technologies, the IEEE Extended Unique Identifier EUI-64 [113] of the access technology the UE uses to connect to the 5GC. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.9.4 5G Globally Unique Temporary Identifier | The AMF shall allocate a 5G Globally Unique Temporary Identifier (5G-GUTI) to the UE that is common to both 3GPP and non-3GPP access. It shall be possible to use the same 5G-GUTI for accessing 3GPP access and non-3GPP access security context within the AMF for the given UE. An AMF may re-assign a new 5G-GUTI to the UE at any time. The AMF provides a new 5G-GUTI to the UE under the conditions specified in clause 6.12.3 of TS 33.501 [29]. When the UE is in CM-IDLE, the AMF may delay providing the UE with a new 5G-GUTI until the next NAS transaction.
The 5G-GUTI shall be structured as:
<5G-GUTI> := <GUAMI> <5G-TMSI>
where GUAMI identifies one or more AMF(s).
When the GUAMI identifies only one AMF, the 5G-TMSI identifies the UE uniquely within the AMF. However, when AMF assigns a 5G-GUTI to the UE with a GUAMI value used by more than one AMF, the AMF shall ensure that the 5G-TMSI value used within the assigned 5G-GUTI is not already in use by the other AMF(s) sharing that GUAMI value.
The Globally Unique AMF ID (GUAMI) shall be structured as:
<GUAMI> := <MCC> <MNC> <AMF Region ID> <AMF Set ID> <AMF Pointer>
where AMF Region ID identifies the region, AMF Set ID uniquely identifies the AMF Set within the AMF Region and AMF Pointer identifies one or more AMFs within the AMF Set.
NOTE 1: The AMF Region ID addresses the case that there are more AMFs in the network than the number of AMFs that can be supported by AMF Set ID and AMF Pointer by enabling operators to re-use the same AMF Set IDs and AMF Pointers in different regions.
NOTE 2: In the case of SNPNs, the PLMN IDs may be shared among SNPNs such that the constructed GUAMIs are not globally unique. However, PLMN ID and NID are provided together, separate from the GUAMI, to uniquely identify selected or supported SNPN in RRC and N2.
NOTE 3: See TS 23.003 [19] for details on the structure of the fields of GUAMI.
The 5G-S-TMSI is the shortened form of the GUTI to enable more efficient radio signalling procedures (e.g. during Paging and Service Request) and is defined as:
<5G-S-TMSI> := <AMF Set ID> <AMF Pointer> <5G-TMSI>
As specified in TS 38.304 [50] and TS 36.304 [52] for 3GPP access, the NG-RAN uses the 10 Least Significant Bits of the 5G-TMSI in the determination of the time at which different UEs are paged. Hence, the AMF shall ensure that the 10 Least Significant Bits of the 5G-TMSI are evenly distributed.
As specified in TS 38.331 [28] and TS 36.331 [51] for 3GPP access, the NG-RAN's RRC Connection Establishment's contention resolution process assumes that there is a low probability of the same 5G-TMSI being allocated by different AMFs to different UEs. The AMFs' process for allocating the 5G-TMSI should take this account.
NOTE 4: To achieve this, the AMF could, for example, use a random seed number for any process it uses when choosing the UE's 5G-TMSI. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.9.5 AMF Name | An AMF is identified by an AMF Name. AMF Name is a globally unique FQDN, the structure of AMF Name FQDN is defined in TS 23.003 [19]. An AMF can be configured with one or more GUAMIs. At a given time, GUAMI with distinct AMF Pointer value is associated to one AMF name only. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.9.6 Data Network Name (DNN) | A DNN is equivalent to an APN as defined in TS 23.003 [19]. Both identifiers have an equivalent meaning and carry the same information.
The DNN may be used e.g. to:
- Select a SMF and UPF(s) for a PDU Session.
- Select N6 interface(s) for a PDU Session.
- Determine policies to apply to this PDU Session.
The wildcard DNN is a value that can be used for the DNN field of Subscribed DNN list of Session Management Subscription data defined in clause 5.2.3.3 of TS 23.502 [3].
The wildcard DNN can be used with an S-NSSAI for operator to allow the subscriber to access any Data Network supported within the Network Slice associated with the S-NSSAI. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.9.7 Internal-Group Identifier | The subscription data for an UE in UDR may associate the subscriber with groups. A group is identified by an Internal-Group Identifier.
NOTE 1: A UE can belong to a limited number of groups, the exact number is defined in stage 3 specifications.
NOTE 2: In this Release of the specification, the support of groups is only defined in non-roaming case.
The Internal-Group Identifier(s) corresponding to an UE are provided by the UDM to the SMF as part Session Management Subscription data and (when PCC applies to a PDU Session) by the SMF to the PCF. The SMF may use this information to apply local policies and to store this information in CDR. The PCF may use this information to enforce AF requests as described in clause 5.6.7.
The Internal-Group Identifier(s) corresponding to an UE are provided by the UDM to the AMF as part of Access and Mobility Subscription data. The AMF may use this information to apply local policies (such as Group specific NAS level congestion control defined in clause 5.19.7.5). |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.9.8 Generic Public Subscription Identifier | Generic Public Subscription Identifier (GPSI) is needed for addressing a 3GPP subscription in different data networks outside of the 3GPP system. The 3GPP system stores within the subscription data the association between the GPSI and the corresponding SUPI.
GPSIs are public identifiers used both inside and outside of the 3GPP system.
The GPSI is either an MSISDN or an External Identifier, see TS 23.003 [19]. If MSISDN is included in the subscription data, it shall be possible that the same MSISDN value is supported in both 5GS and EPS.
NOTE: There is no implied 1-to-1 relationship between GPSI and SUPI. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.9.9 AMF UE NGAP ID | An AMF UE NGAP ID is an identifier used to identify the UE in AMF on N2 reference point. AMF allocates the AMF UE NGAP ID and send it to the 5G-AN. For the following N2 signalling interaction sent from 5G-AN to AMF, AMF UE NGAP ID is used to identify the UE at the AMF. AMF UE NGAP ID is unique per AMF set. AMF UE NGAP ID may be updated without AMF change, or with AMF change as specified at clause 5.21.2.2. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.9.10 UE Radio Capability ID | The UE Radio Capability ID is a short pointer with format defined in TS 23.003 [19] that is used to uniquely identify a set of UE Radio Capabilities (excluding UTRAN and NB-IoT capabilities). The UE Radio Capability ID is assigned either by the serving PLMN or by the UE manufacturer, as follows:
- UE manufacturer-assigned: The UE Radio Capability ID may be assigned by the UE manufacturer in which case it includes a UE manufacturer identification (i.e. a Vendor ID). In this case, the UE Radio Capability ID uniquely identifies a set of UE radio capabilities and the UE Radio Capability for Paging for a UE by this manufacturer in any PLMN.
- PLMN-assigned: If a UE manufacturer-assigned UE Radio Capability ID is not used by the UE or the serving network, or it is not recognised by the serving PLMN UCMF, the UCMF may allocate UE Radio Capability IDs for the UE corresponding to each different set of UE radio capabilities the PLMN may receive from the UE at different times. In this case, the UE Radio Capability IDs the UE receives are applicable to the serving PLMN and uniquely identify the corresponding sets of UE radio capabilities and and the UE Radio Capability for Paging(s) in this PLMN. The PLMN assigned UE Radio Capability ID includes a Version ID in its format. The value of the Version ID is the one configured in the UCMF, at time the UE Radio Capability ID value is assigned. The Version ID value makes it possible to detect whether a UE Radio Capability ID is current or outdated.
NOTE: For the case the PLMN is configured to store PLMN assigned IDs in the UE manufacturer-assigned operation requested list defined in clause 5.4.4.1a, then the algorithm for assignment of PLMN-assigned UE Radio Capability ID shall assign different UE Radio Capability IDs for UEs with different TAC value.
The type of UE Radio Capability ID (UE manufacturer-assigned or PLMN-assigned) is distinguished when a UE Radio Capability ID is signalled. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.10 Security aspects | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.10.1 General | The security features in the 5G System include:
- Authentication of the UE by the network and vice versa (mutual authentication between UE and network).
- Security context generation and distribution.
- User Plane data confidentiality and integrity protection.
- Control Plane signalling confidentiality and integrity protection.
- User identity confidentiality.
- Support of LI requirements as specified in TS 33.126 [35] subject to regional/national regulatory requirements, including protection of LI data (e.g. target list) that may be stored or transferred by an NF.
Detailed security related network functions for 5G are described in TS 33.501 [29]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.10.2 Security Model for non-3GPP access | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.10.2.1 Signalling Security | When a UE is connected via a NG-RAN and via a standalone non-3GPP accesses, the multiple N1 instances are secured using independent NAS security contexts, each created based on the security context in the corresponding SEAF (e.g. in the common AMF when the UE is served by the same AMF) derived from the UE authentication. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.10.3 PDU Session User Plane Security | The User Plane Security Enforcement information provides the NG-RAN with User Plane security policies for a PDU session. It indicates:
- whether UP integrity protection is:
- Required: for all the traffic on the PDU Session UP integrity protection shall apply.
- Preferred: for all the traffic on the PDU Session UP integrity protection should apply.
- Not Needed: UP integrity protection shall not apply on the PDU Session.
- whether UP confidentiality protection is:
- Required: for all the traffic on the PDU Session UP confidentiality protection shall apply.
- Preferred: for all the traffic on the PDU Session UP confidentiality protection should apply.
- Not Needed: UP confidentiality shall not apply on the PDU Session.
User Plane Security Enforcement information applies only over 3GPP access. Once determined at the establishment of the PDU Session the User Plane Security Enforcement information applies for the life time of the PDU Session.
NOTE 1: Applicability of UP integrity protection of UP Security Enforcement is defined in TS 33.501 [29] and TS 38.300 [27].
The SMF determines at PDU session establishment a User Plane Security Enforcement information for the user plane of a PDU session based on:
- subscribed User Plane Security Policy which is part of SM subscription information received from UDM; and
- User Plane Security Policy locally configured per (DNN, S-NSSAI) in the SMF that is used when the UDM does not provide User Plane Security Policy information.
- The maximum supported data rate per UE for integrity protection for the DRBs, provided by the UE in the Integrity protection maximum data rate IE during PDU Session Establishment. The UE supporting NR as primary RAT, i.e. NG-RAN access via Standalone NR, shall set the Integrity protection maximum data rate IE for Uplink and Downlink to full rate at PDU Session Establishment as defined in TS 24.501 [47]. A UE not supporting NR as primary RAT and supporting E-UTRA connected to 5GC, shall set the Integrity protection maximum data rate IE for Uplink and Downlink to NULL at PDU Session Establishment as defined in TS 24.501 [47].
The User Plane Security Enforcement information provides the MME with User Plane integrity protection policies for the PDU session (PDN Connection). The information indicates whether UP integrity protection is:
- Required: for all the traffic on the PDU Session (PDN Connection) UP integrity protection shall apply.
- Preferred: for all the traffic on the PDU Session (PDN Connection) UP integrity protection should apply.
- Not Needed: UP integrity protection shall not apply on the PDU Session (PDN Connection).
In turn, the MME provides per EPS bearer User Plane Security Enforcement information to the E-UTRAN. All the bearers within a PDN Connection share the same User Plane integrity protection policies.
The UE capability to support user plane integrity protection with EPS is indicated to AMF in the S1 UE network capability information. If the UE supports user plane integrity protection with EPS and the AMF supports the associated functionality, the AMF indicates this to SMF at PDU Session Establishment using NG-RAN. If the UE and AMF support user plane integrity protection with EPS, for PDU Sessions with UP integrity protection of UP Security Enforcement Information set to Required, the SMF may perform the EPS bearer ID allocation procedure as described in TS 23.502 [3] clause 4.11.1.4. If the UE does not support user plane integrity protection with EPS or the AMF does not support the associated functionality, the SMF shall not trigger the EPS bearer ID allocation procedure in clause 4.11.1.4 of TS 23.502 [3].
Unless the UE, the serving eNB and the MME support user plane integrity protection with EPS, the SMF+PGW-C shall reject a PDN Connection Establishment using EPS if the UP Security Enforcement Information has UP integrity protection set to Required.
The SMF+PGW-C shall (e.g. based on the received RAT Type) reject a PDN Connection Establishment using GERAN/UTRAN if the UP Security Enforcement Information has UP integrity protection set to Required.
NOTE 2: This assumes that the optional user plane integrity protection for GPRS specified in Release 13 has not been deployed.
The SMF may, based on local configuration, reject the PDU Session Establishment request depending on the value of the maximum supported data rate per UE for integrity protection.
NOTE 3: Reasons to reject a PDU Session Establishment request can e.g. be that the UP Integrity Protection is determined to be "Required" while the maximum supported data rate per UE for integrity protection is less than the expected required data rate for the DN.
NOTE 4: The operator can take care to reduce the risk of such rejections when configuring the subscribed User Plane Security Policy for a DNN. For example, the operator may apply integrity protection "Required" only in scenarios where it can be assumed that the UE maximum supported data rate per UE for integrity protection is likely to be adequate for the DN.
The User Plane Security Policy provide the same level of information than User Plane Security Enforcement information.
User Plane Security Policy from UDM takes precedence over locally configured User Plane Security Policy.
The User Plane Security Enforcement information may include the maximum supported data rate for integrity protection provided by the UE, is communicated from SMF to the NG-RAN for enforcement as part of PDU session related information. If the UP Integrity Protection is determined to be "Required" or "Preferred", the SMF also provides the maximum supported data rate per UE for integrity protection as received in the Integrity protection maximum data rate IE. This takes place at establishment of a PDU Session or at activation of the user plane of a PDU Session. The NG-RAN rejects the establishment of UP resources for the PDU Session when it cannot fulfil User Plane Security Enforcement information with a value of Required. The NG-RAN may also take the maximum supported data rate per UE for integrity protection into account in its decision on whether to accept or reject the establishment of UP resources. In this case the SMF releases the PDU Session. The NG-RAN notifies the SMF when it cannot fulfil a User Plane Security Enforcement with a value of Preferred.
NOTE 5: For example, the NG-RAN cannot fulfil requirements in User Plane Security Enforcement information with UP integrity protection set to "Required" when it cannot negotiate UP integrity protection with the UE.
It is responsibility of the NG-RAN to enforce that the maximum UP integrity protection data rate delivered to the UE in downlink is not exceeding the maximum supported data rate for integrity protection.
It is expected that generally the UP integrity protection data rate applied by the UE in uplink will not exceed the indicated maximum supported data rate, but the UE is not required to perform strict rate enforcement.
User Plane Security Enforcement information and the maximum supported data rate per UE for integrity protection is communicated from source to target NG-RAN node at handover. If the target RAN node cannot support requirements in User Plane Security Enforcement information, the target RAN node rejects the request to set up resources for the PDU Session. In this case the PDU Session is not handed over to the target RAN node and the PDU Session is released.
If the UE or the new eNB or the MME does not indicate support of user plane integrity protection with EPS, PDU Sessions with UP integrity protection of the User Plane Security Enforcement information set to Required are not transferred to EPS as follows:
- In the case of mobility without N26, the SMF+PGW-C shall reject a PDN connectivity request in EPS with handover indication if the UP integrity protection of the User Plane Security Enforcement is set to Required.
NOTE 6: As described in clause 5.17.2.3.3, the UE does not know before trying to move a given PDU Session to EPC, whether that PDU session can be transferred to EPC.
- In the case of idle mode and connected mode mobility with N26 to EPS, or mobility without N26, the SMF+PGW-C ensures that the PDU session is released.
If the UE, target eNB and the target MME indicate support of User Plane Integrity Protection with EPS, PDU Sessions with UP integrity protection of the User Plane Security Enforcement information set to Required are transferred from 5GS to EPS according to existing procedures.
For the bearers of PDN Connections with UP integrity protection set to Required, at (both idle mode and connected mode) mobility (including intra-TA mobility) to an eNB that does not support User Plane Integrity Protection with EPS, the MME shall inform the SMF+PGW-C and the SMF+PGW-C ensures that the PDU session is released.
At connected mode mobility from EPS to GERAN/UTRAN or to a part of the EPS that does not support User Plane Integrity Protection, the source E-UTRAN shall ensure that EPS bearers with UP integrity protection of the User Plane Security Enforcement information set to Required are not handed over.
In the case of idle mode mobility from an MME that supports User Plane Integrity Protection, to an MME that does not support User Plane Integrity Protection, the (home) SMF+PGW-C shall trigger (e.g. based on the lack of MME UPIP capability information) the release of the bearers of PDN Connections with UP integrity protection set to Required.
At any (e.g. idle mode) mobility from EPS to GERAN/UTRAN, the (home) SMF+PGW-C shall trigger (e.g. based on the received RAT Type) the release of the bearers of PDN Connections with UP integrity protection set to Required.
PDU Sessions with UP confidentiality protection of the User Plane Security Enforcement information set to Required and UP integrity protection of the User Plane Security Enforcement information not set to Required, are allowed to be handed over to EPS regardless of how UP confidentiality protection applies in EPS.
In the case of dual connectivity, the Integrity Protection is set to "Preferred", the Master RAN node may notify the SMF when it cannot fulfil a User Plane Security Enforcement with a value of Preferred. The SMF handling of the PDU session with respect to the Integrity Protection status is up to SMF implementation decision. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.11 Support for Dual Connectivity, Multi-Connectivity | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.11.1 Support for Dual Connectivity | Dual Connectivity involves two radio network nodes in providing radio resources to a given UE (with active radio bearers), while a single N2 termination point exists for the UE between an AMF and the RAN. The RAN architecture and related functions to support Dual Connectivity is further described in RAN specifications (e.g. TS 37.340 [31]).
In this Release of the specification, the Dual Connectivity function does not apply to the NR RedCap UE.
The RAN node at which the N2 terminates, performs all necessary N2 related functions such as mobility management, relaying of NAS signalling, etc. and manages the handling of user plane connection (e.g. transfer over N3). It is called the Master RAN Node. It may use resources of another RAN node, the Secondary RAN node, to exchange User Plane traffic of an UE. Master RAN node takes into account the RSN and/or PDU Session Pair ID to determine if dual connectivity shall be set up and ensure appropriate PDU session handling ensures fully redundant user plane path as described in clause 5.33.2.1.
If the UE has Mobility Restriction (either signalled from the UDM, or, locally generated by the Serving PLMN policy in the AMF) the AMF signals these restrictions to the Master RAN Node as Mobility Restriction List; This may prevent the Master RAN node from setting up a Dual Connectivity for an UE.
NOTE 1: Subject to policies in the NG-RAN, configuration of Dual Connectivity for a Data Radio Bearer can also be based on the Network Slice that the PDU Session belongs to.
Dual Connectivity provides the possibility for the Master RAN node to request SMF:
- For some or all PDU Sessions of an UE: Direct all the DL User Plane traffic of the PDU Session to the either the Master RAN Node or to the Secondary RAN Node. In this case, there is a single N3 tunnel termination at the RAN for such PDU Session.
NOTE 2: The terminating RAN Node, can decide to keep traffic for specific QFI(s) in a PDU Session for a UE on a single RAT, or split them across the two RATs.
- For some other PDU Sessions of an UE: Direct the DL User Plane traffic of some QoS Flows of the PDU Session to the Secondary (respectively Master) RAN Node while the remaining QoS Flows of the PDU Session are directed to the Master (respectively Secondary) RAN Node. In this case there are, irrespective of the number of QoS Flows, two N3 tunnel terminations at the RAN for such PDU Session.
The Master RAN node may create and change this assignment for the user plane of a PDU Session at any time during the life time of the PDU Session;
In both cases, a single PDU Session Id is used to identify the PDU Session.
Additional functional characteristics are:
- User location information is based on the identity of the cell that is serving the UE in the Master RAN node. The cell identity of the Primary cell in the secondary RAN node may also be included. NG-RAN includes the user location information in NGAP messages where the contents of the user location information may change during the corresponding procedure.
- Path update signalling related with Dual Connectivity and UPF re-allocation cannot occur at the same time. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.12 Charging | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.12.1 General | 5GC supports interactions towards CHF for network resource usage, as defined in TS 32.240 [41]. The CHF and the Nchf service are defined in TS 32.290 [67].
The SMF supports the interactions towards the CHF, as defined in TS 32.255 [68]. The UPF supports functionality to collect and report usage data to SMF. The N4 reference point supports the SMF control of the UPF collection and reporting of usage data.
The AMF supports interactions towards the CHF, as defined in TS 32.256 [114].
The SMSF supports interactions towards the CHF, as defined in TS 32.274 [118].
The NEF supports interactions towards the CHF, as defined in TS 32.254 [123]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.12.2 Usage Data Reporting for Secondary RAT | When NG-RAN is deployed in dual connectivity configuration, the HPLMN or VPLMN operator may wish to record the data volume sent and received on the Secondary RAT.
In order to reduce the complexity of this procedure, the following principles are used in this release:
a) The PLMN locally activates the Secondary RAT Usage Data Reporting by NG-RAN OAM. The activation is based on configuration in NG-RAN and NG-RAN determines whether the data volume report will contain data volumes consumed for the whole PDU Session or for selected QoS Flows or both as described in TS 38.413 [34].
The activation can happen separately for Data Volume Reporting of NR in licensed or unlicensed spectrum and E-UTRA in licensed or unlicensed spectrum. If the PLMN uses this feature, it should ensure that this functionality is supported by all NG-RAN nodes that support NR or E-UTRA as a Secondary RAT.
b) Depending on its configuration the NG-RAN reports uplink and downlink data volumes to the 5GC for the Secondary RAT (including the using of unlicensed spectrum for NR or E-UTRA) for the PDU Session or for selected QoS Flows or both and per time interval.
c) During Xn handover and N2 handover, the source NG-RAN node reports the data volume to the 5GC. The reported data volume excludes data forwarded to the target RAN node.
d) At the time of NG connection release, Secondary RAN Node change/release, deactivation of UP connection for a PDU Session, the NG-RAN node reports the data volumes to the 5GC.
e) To assist "partial CDR" generation, NG-RAN OAM can instruct the NG-RAN to also make periodic reports (as described in clause 5.12.3) if no event has triggered a report before the period expires.
NOTE 2: The timing of these periodic NG-RAN reports is not expected to align with the timing of partial CDR generation. Hence the frequency of NG-RAN reports might be greater than that of partial CDR generation.
NOTE 3: RAN needs to be able to partition the measurements in a report to indicate usage that occurred before and after an absolute time. An example of the absolute time is that RAN is configured to partition data usage reports that occurred before and after midnight. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.12.3 Secondary RAT Periodic Usage Data Reporting Procedure | Periodic reporting of the Secondary RAT usage data is an optional function. When NG-RAN, as defined in bullet e) of clause 5.12.12, is configured with a "time interval for Secondary RAT usage data reporting", the NG-RAN shall send a RAN Usage Data Report message for periodic reporting purposes to the SMF only when the timer expires for a UE for which Secondary RAT usage data reporting is ongoing. The timer runs from the last usage reporting for the UE. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.13 Support for Edge Computing | Edge computing enables operator and 3rd party services to be hosted close to the UE's access point of attachment, so as to achieve an efficient service delivery through the reduced end-to-end latency and load on the transport network. Edge Computing support by 5GC is specified in this specification and in TS 23.548 [130].
NOTE 1: Edge Computing typically applies to non-roaming and LBO roaming scenarios. For HR roaming scenarios, Edge Computing applies only for "Home Routed with Session Breakout in VPLMN (HR-SBO)" which is described in clause 6.7 of TS 23.548 [130].
The 5G Core Network selects a UPF close to the UE and forwards traffic to enable the local access to the DN via a N6 interface according to the provided traffic steering rules to the UPF. This may be based on the UE's subscription data, UE location, the information from Application Function (AF) as defined in clause 5.6.7, the EAS information reported from EASDF (as defined in TS 23.548 [130]), policy, user plane latency (between the 5G AN and candidate UPF(s)), N6 delay measurement results or other related traffic rules.
NOTE 2: Latencies between 5GC AN and UPF(s) can be configured. If QoS monitoring has previously been performed, the delays of such measurements can also be used.
Due to user or Application Function mobility, the service or session continuity may be required based on the requirements of the service or the 5G network.
The 5G Core Network may expose network information and capabilities to an Edge Computing Application Function.
NOTE 3: Depending on the operator deployment, certain Application Functions can be allowed to interact directly with the Control Plane Network Functions with which they need to interact, while the other Application Functions need to use the external exposure framework via the NEF (see clause 6.2.10 for details).
Edge computing can be supported by one or a combination of the following enablers:
- User plane (re)selection: the 5G Core Network (re)selects UPF to route the user traffic to the local part of the DN as described in clause 6.3.3;
- Local Routing and Traffic Steering: the 5G Core Network selects the traffic to be routed to the applications in the local part of the DN;
- this includes the use of a single PDU Session with multiple PDU Session Anchor(s) (UL CL / IP v6 multi-homing) as described in clause 5.6.4 and the use of a PDU Session with Distributed Anchor Point using SSC mode 2/3.
- Session and service continuity to enable UE and application mobility as described in clause 5.6.9;
- An Application Function may influence UPF (re)selection and traffic routing via PCF or NEF as described in clause 5.6.7;
- Network capability exposure: 5G Core Network and Application Function to provide information to each other via NEF as described in clause 5.20 or directly as described in clause 4.15 of TS 23.502 [3] or from the UPF as described in clause 6.4 of TS 23.548 [130];
- QoS and Charging: PCF provides rules for QoS Control and Charging for the traffic routed to the local part of the DN;
- Support of Local Area Data Network: 5G Core Network provides support to connect to the LADN in a certain area where the applications are deployed as described in clause 5.6.5.
- Discovery and re-discovery of Edge Applications Servers as described in TS 23.548 [130].
- Support of Edge Relocation as described in TS 23.548 [130] and the case of involving AF change as described in clauses 4.3.6.2, 4.3.6.3 and 4.3.6.4 of TS 23.502 [3]. Support of 5GC triggered Edge relocation within the same hosting PLMN's EHEs.
- Support of (I-)SMF (re)selection based on DNAI as described in clauses 4.3.5.1, 4.3.5.2 and 4.23.5.1 of TS 23.502 [3].
- Support of finer sets of UEs.
- Support of common EAS discovery and common DNAI determination for set of UEs as described in clause 6.2 of TS 23.548 [130].
- Support of mapping information between EAS IP/IP range and DNAI as described in clause 6.8 of TS 23.548 [130].
- Support of AF request for DNAI as described in clause 6.8 of TS 23.548 [130].
- Support of Local Offloading Management with I-SMF insertion as described in clause 4.23 of TS 23.502 [3] and in clause 6.10 of TS 23.548 [130].
- Support of N6 delay measurement and reporting as described in clause 5.8.2.23. Support of L-PSA UPF (re-)selection and/or an edge relocation considering N6 delay measurement and user plane latency requirement which may trigger an EAS (re-)discovery as described in TS 23.548 [130]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.14 Policy Control | The policy and charging control framework for the 5G System is defined in TS 23.503 [45]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.15 Network slicing | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.15.1 General | A Network Slice instance is defined within a PLMN or within an SNPN and shall include:
- the Core Network Control Plane and User Plane Network Functions, as described in clause 4.2,
and, in the serving PLMN, at least one of the following:
- the NG-RAN described in TS 38.300 [27];
- the N3IWF or TNGF functions to the non-3GPP Access Network described in clause 4.2.8.2 or the TWIF functions to the trusted WLAN in the case of support of N5CW devices described in clause 4.2.8.5;
- the W-AGF function to the Wireline Access Network described in clause 4.2.8.4.
The 5G System deployed in a PLMN shall always support the procedures, information and configurations specified to support Network Slice instance selection in the present document, TS 23.502 [3] and TS 23.503 [45].
NOTE 1: Management of network slices are described in TS 28.530 [175], the procedures for provisioning of networks and network slices are described in TS 28.531 [176] and TS 28.541 [149] describes the resource model for managing the resources.
Network slicing support for roaming is described in clause 5.15.6.
Network slices may differ for supported features and network functions optimisations, in which case such Network Slices may have e.g. different S-NSSAIs with different Slice/Service Types (see clause 5.15.2.1). The operator can deploy multiple Network Slices delivering exactly the same features but for different groups of UEs, e.g. as they deliver a different committed service and/or because they are dedicated to a customer, in which case such Network Slices may have e.g. different S-NSSAIs with the same Slice/Service Type but different Slice Differentiators (see clause 5.15.2.1).
The network may serve a single UE with one or more Network Slice instances simultaneously via a 5G-AN regardless of the access type(s) over which the UE is registered (i.e. 3GPP Access and/or N3GPP Access). The AMF instance serving the UE logically belongs to each of the Network Slice instances serving the UE, i.e. this AMF instance is common to the Network Slice instances serving a UE.
NOTE 2: Number of simultaneous connection of Network Slice instances per UE is limited by the number of S-NSSAIs in the Requested/Allowed NSSAI as described in clause 5.15.2.1.
NOTE 3: In this Release of the specification it is assumed that in any (home or visited) PLMN it is always possible to select an AMF that can serve any combination of S-NSSAIs that will be provided as an Allowed NSSAI.
The selection of the set of Network Slice instances for a UE is triggered by the first contacted AMF in a Registration procedure normally by interacting with the NSSF and can lead to a change of AMF. This is further described in clause 5.15.5.
A PDU Session belongs to one and only one specific Network Slice instance per PLMN. Different Network Slice instances do not share a PDU Session, though different Network Slice instances may have slice-specific PDU Sessions using the same DNN.
During the Handover procedure the source AMF selects a target AMF by interacting with the NRF as specified in clause 6.3.5.
Network Slice-Specific Authentication and Authorization (NSSAA) enables Network Slice specific authentication as described in clause 5.15.10.
Network Slice Admission Control (NSAC) controls the number of registered UEs per network slice, the number of UEs with at least one PDU Session/PDN Connection per network slice in the case of EPC interworking and the number of PDU Sessions per network slice as described in clause 5.15.11.
Support of subscription-based restrictions to simultaneous registration of network slices uses Network Slice Simultaneous Registration Group (NSSRG) information to enable control of which Network Slices that can be registered simultaneously by a UE as described in clause 5.15.12.
Support of data rate limitation per Network Slice for a UE enables enforcement of Maximum Bit Rate per Network Slice for a UE as described in clause 5.15.13.
The selection of N3IWF/TNGF supporting a set of slice(s) is described in clause 6.3.6 and clause 6.3.12 respectively.
The support of Network Slice usage control is described in clause 5.15.15.
Support of Optimized handling of temporarily available network slices is described in clause 5.15.16. It also covers aspects related to graceful release of network slices connectivity during slice decommissioning.
The Partial Network Slice support in a Registration Area is described in clause 5.15.17.
Support for Network Slices with Network Slice Area of Service not matching deployed Tracking Areas is described in clause 5.15.18.
Support of Network Slice Replacement is described in clause 5.15.19. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.15.2 Identification and selection of a Network Slice: the S-NSSAI and the NSSAI | |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.15.2.1 General | An S-NSSAI identifies a Network Slice.
An S-NSSAI is comprised of:
- A Slice/Service type (SST), which refers to the expected Network Slice behaviour in terms of features and services;
- A Slice Differentiator (SD), which is optional information that complements the Slice/Service type(s) to differentiate amongst multiple Network Slices of the same Slice/Service type.
An S-NSSAI can have standard values (i.e. such S-NSSAI is only comprised of an SST with a standardised SST value, see clause 5.15.2.2 and no SD) or non-standard values (i.e. such S-NSSAI is comprised of either both an SST and an SD or only an SST without a standardised SST value and no SD). An S-NSSAI with a non-standard value identifies a single Network Slice within the PLMN with which it is associated. An S-NSSAI with a non-standard value shall not be used by the UE in access stratum procedures in any PLMN other than the one to which the S-NSSAI is associated.
The S-NSSAIs in the NSSP of the URSP rules (see clause 6.6.2 of TS 23.503 [45]) and in the Subscribed S-NSSAIs (see clause 5.15.3) contain only HPLMN S-NSSAI values.
The S-NSSAIs in the Configured NSSAI, the Allowed NSSAI (see clause 5.15.4.1), the Requested NSSAI (see clause 5.15.5.2.1), the Rejected S-NSSAIs contain only values from the Serving PLMN. The Serving PLMN can be the HPLMN or a VPLMN.
The S-NSSAI(s) in the PDU Session Establishment contain one Serving PLMN S-NSSAI value and in addition may contain a corresponding HPLMN S-NSSAI value to which this first value is mapped (see clause 5.15.5.3). Further information for slice replacement is described in clause 5.15.19.
The optional mapping of Serving PLMN S-NSSAIs to HPLMN S-NSSAIs contains Serving PLMN S-NSSAI values and corresponding mapped HPLMN S-NSSAI values.
The NSSAI is a collection of S-NSSAIs. An NSSAI may be a Configured NSSAI, a Requested NSSAI, Allowed NSSAI or a Partially Allowed NSSAI. There can be at most eight S-NSSAIs in Allowed NSSAI and Requested NSSAI sent in signalling messages between the UE and the Network. There can be at most seven S-NSSAIs in the Partially Allowed NSSAI and at most seven S-NSSAIs rejected partially in the RA and the sum of S-NSSAIs in the Allowed NSSAI and the Partially Allowed NSSAI shall be at most eight. The Requested NSSAI signalled by the UE to the network allows the network to select the Serving AMF, Network Slice(s) and Network Slice instance(s) for this UE, as specified in clause 5.15.5.
NOTE 1: There can be at most a maximum of seven S-NSSAIs in the Partially Allowed NSSAI since there will always be an Allowed NSSAI allocated.
Based on the operator's operational or deployment needs, a Network Slice instance can be associated with one or more S-NSSAIs and an S-NSSAI can be associated with one or more Network Slice instances. Multiple Network Slice instances associated with the same S-NSSAI may be deployed in the same or in different Tracking Areas. When multiple Network Slice instances associated with the same S-NSSAI are deployed in the same Tracking Areas, the AMF instance serving the UE may logically belong to (i.e. be common to) more than one Network Slice instance associated with this S-NSSAI.
In a PLMN, when an S-NSSAI is associated with more than one Network Slice instance, one of these Network Slice instances, as a result of the Network Slice instance selection procedure defined in clause 5.15.5, serves a UE that is allowed to use this S-NSSAI. For any S-NSSAI, the network may at any one time serve the UE with only one Network Slice instance associated with this S-NSSAI until cases occur where e.g. this Network Slice instance is no longer valid in a given Registration Area, or a change in UE's Allowed NSSAI occurs, etc. In such cases, procedures mentioned in clause 5.15.5.2.2 or clause 5.15.5.2.3 apply.
Based on the Requested NSSAI (if any) and the Subscription Information, the 5GC is responsible for selection of a Network Slice instance(s) to serve a UE including the 5GC Control Plane and User Plane Network Functions corresponding to this Network Slice instance(s). The Subscription Information may contain restrictions to the simultaneous registration of network slices. This is provided to the serving AMF as part of the UE subscription, in the form of Network Slice Simultaneous Registration Group (NSSRG) information (see clause 5.15.12).
The (R)AN may use Requested NSSAI in access stratum signalling to handle the UE Control Plane connection before the 5GC informs the (R)AN of the Allowed NSSAI. The Requested NSSAI is used by the RAN for AMF selection, as described in clause 6.3.5. The UE shall not include the Requested NSSAI in the RRC Resume when the UE asks to resume the RRC connection and is CM-CONNECTED with RRC_INACTIVE state.
When a UE is successfully registered over an Access Type, the CN informs the (R)AN by providing the Allowed NSSAI for the corresponding Access Type.
NOTE 2: The details of how the RAN uses NSSAI information are described in TS 38.300 [27]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.15.2.2 Standardised SST values | Standardized SST values provide a way for establishing global interoperability for slicing so that PLMNs can support the roaming use case more efficiently for the most commonly used Slice/Service Types.
The SSTs which are standardised are in the following Table 5.15.2.2-1.
Table 5.15.2.2-1: Standardised SST values
Slice/Service type
SST value
Characteristics
eMBB
1
Slice suitable for the handling of 5G enhanced Mobile Broadband.
URLLC
2
Slice suitable for the handling of ultra- reliable low latency communications.
MIoT
3
Slice suitable for the handling of massive IoT.
V2X
4
Slice suitable for the handling of V2X services.
HMTC
5
Slice suitable for the handling of High-Performance Machine-Type Communications.
HDLLC
6
Slice suitable for the handling of High Data rate and Low Latency Communications.
GBRSS
7
Slice suitable for the handling of Guaranteed Bit Rate Streaming Service.
NOTE 1: The support of all standardised SST values is not required in a PLMN. Services indicated in this table for each SST value can also be supported by means of other SSTs.
NOTE 2: A mapping of GSMA defined Network Slice Types (NEST) to standard SST values is defined in GSMA NG.116 [137]. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.15.3 Subscription aspects | The Subscription Information shall contain one or more S-NSSAIs i.e. Subscribed S-NSSAIs. The subscription information shall include at least one default S-NSSAI. The UDM sends at the most 16 Subscribed S-NSSAIs to AMF, i.e. the number that can fit in a Configured NSSAI. The subscription information the UDM sends to the AMF shall include at least one default S-NSSAI.
If an S-NSSAI is marked as default, then the network is expected to serve the UE with a related applicable Network Slice instance when the UE does not send any permitted S-NSSAI to the network in a Registration Request message as part of the Requested NSSAI.
The Subscription Information for each S-NSSAI may contain:
- a Subscribed DNN list and one default DNN; and
- the indication whether the S-NSSAI is marked as default Subscribed S-NSSAI; and
- the indication whether the S-NSSAI is subject to Network Slice-Specific Authentication and Authorization; and
- Network Slice Simultaneous Usage Group (NSSRG) information (see clause 5.15.12).
The network verifies the Requested NSSAI the UE provides in the Registration Request against the Subscription Information. For the S-NSSAIs subject to Network Slice-Specific Authentication and Authorization the clause 5.15.10 applies.
NOTE 1: It is recommended that at least one of the Subscribed S-NSSAIs marked as default S-NSSAI is not subject to Network Slice-specific Authentication and Authorization, in order to ensure access to services even when Network Slice-specific Authentication and Authorization fails.
NOTE 2: It is recommended to minimize the number of Subscribed S-NSSAIs in subscriptions for NB-IoT or NR RedCap capable UEs to minimize overhead for signalling a large number of S-NSSAIs in Requested NSSAI in RRC and NAS via NB-IoT or NR RedCap.
In roaming case, the UDM shall provide to the VPLMN only the S-NSSAIs from the Subscribed S-NSSAIs the HPLMN allows for the UE in the VPLMN. If the UE is subject to restrictions of simultaneous registration of network slices (i.e. if the Subscription Information for the S-NSSAIs contains NSSRG information), the UDM provides to the VPLMN a subscribed S-NSSAIs and, if applicable, NSSRG information, as described in clause 5.15.12.
NOTE 3: Network slice instances supporting an S-NSSAI subject to Network Slice-Specific Authentication and Authorization need to be deployed with AMFs supporting Network Slice-Specific Authentication and Authorization, otherwise S-NSSAIs requiring Network Slice-Specific Authentication and Authorization would be incorrectly allowed without execution of Network Slice-Specific Authentication and Authorization.
NOTE 4: Network slice instances supporting an S-NSSAI subject to Network Slice Admission Control (NSAC) for number of registered UE per network slice need to be deployed with AMFs supporting NSAC, otherwise S-NSSAIs requiring NSAC would be incorrectly allowed without execution of NSAC.
When the UDM updates the Subscribed S-NSSAI(s) to the serving AMF, based on configuration in this AMF, the AMF itself or the NSSF determines the mapping of the Configured NSSAI for the Serving PLMN and/or Allowed NSSAI to the Subscribed S-NSSAI(s). The serving AMF then updates the UE with the above information as described in clause 5.15.4. |
fbecc7f0dcf9784c6066646052ab0c0e | 23.501 | 5.15.4 UE NSSAI configuration and NSSAI storage aspects |
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