5G Roaming (Home-Routed) — Tracing SEPP and N32

A subscriber from Home PLMN (HPLMN, MCC-MNC 525-01, Singapore) is roaming in Visited PLMN (VPLMN, MCC-MNC 310-260, US). They successfully attach and get service but complain that data service is intermittent. You've been asked to verify the N32 signalling between V-SEPP (Visited 10.45.9.1) and H-SEPP (Home 10.45.0.9). The two operators interconnect through an IPX provider that only routes traffic at the IP layer. The trace includes the home-routed PDU session set-up (V-SMF to H-SMF over N16), whose user plane anchors at the home UPF. Your goal: understand the SEPP architecture, verify SEPP is doing its job, and identify whether the intermittent issue could be an N32-c vs N32-f signalling problem. Keep the two connections apart. N32-c is always its own TLS connection and is never PRINS-wrapped. On N32-f, a path whose intermediary only routes permits either TLS or PRINS (TS 33.501 §13.1.2), and these two SEPPs agreed PRINS. So every N32-f request should reach H-SEPP from V-SEPP as a reformatted /n32f-forward/v1/n32f-process message. Check which messages follow that rule.