N.1 NAT identification

26.2343GPPProtocols and codecsRelease 17Transparent end-to-end Packet-switched Streaming Service (PSS)TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

The PSS client should first identify whether or not there is a NAT in the path. The PSS client may, for future sessions, store the information whether or not the presence of a NAT has been identified for an access system.

Active Mode: The client actively discovers the presence of a NAT using STUN (RFC 3489).

Passive Mode: The PSS client should monitor whether or not UDP packets arrive after the RTSP PLAY request was issued. If no UDP packets have arrived after some seconds, the PSS client should assume the presence of a NAT/Firewall for this access system.