6.1.10 HTTP redirection

29.5023GPP5G SystemRelease 16Session Management ServicesStage 3TS

An HTTP request may be redirected to a different SMF service instance, within the same SMF or a different SMF of an SMF set, e.g. when an SMF service instance is part of an SMF (service) set or when using indirect communications (see 3GPP TS 29.500 [4]). See also the ES3XX feature in clause 6.1.8.

An SCP that reselects a different SMF producer instance will return the NF Instance ID of the new SMF producer instance in the 3gpp-Sbi-Producer-Id header, as specified in clause 6.10.3.4 of 3GPP TS 29.500 [4].

If an SMF within an SMF set redirects a service request to a different SMF of the set using an 307 Temporary Redirect or 308 Permanent Redirect status code, the identity of the new SMF towards which the service request is redirected shall be indicated in the 3gpp-Sbi-Target-Nf-Id header of the 307 Temporary Redirect or 308 Permanent Redirect response as specified in clause 6.10.9.1 of 3GPP TS 29.500 [4].

For a HR PDU session or a PDU session with an I-SMF, the V-SMF or I-SMF shall update the AMF upon detecting a change of the H-SMF or SMF within the SMF set, by sending an SM context status notification with the resourceStatus set to "UPDATED", the cause in statusInfo set to "CHANGED_ANCHOR_SMF" and with the new H-SMF or SMF identity (see clause 5.2.2.5.1).

NOTE: This allows the AMF to receive the NF Instance ID of the new SMF handling the PDU session and to send the NF Instance ID of the last known SMF handling the PDU session during inter-AMF mobility.

Annex A (normative):
OpenAPI specification