C.1 General

29.5733GPP5G SystemPublic Land Mobile Network (PLMN) InterconnectionRelease 18Stage 3TS

This Annex provides an informative reference for how the end to end call flow works when the NF service consumer and the NF service producer are in different PLMNs and SEPP is involved on path.

The following clauses explain how the HTTP messages are forwarded between NF services in two PLMNs via the SEPP. In these clauses, the following aspects are not shown to avoid cluttering of the figures and procedure:

– Resolution of FQDN into an IP address using DNS. TCP / TLS connection for sending the HTTP/2 messages is initiated towards the IP address obtained from DNS resolution.

When https URI scheme is used, TLS protection between the Network Function and the SEPP may rely on using telescopic FQDN or 3gpp-Sbi-Target-apiRoot header. See clause 6.1.4.3 of 3GPP TS 29.500 [4].