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) that satisfies the security requirements given in clause T.5 of TS 33.501 [29], 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].