3GPP 23.501 v20.2.0 — the document's own text
U.3 Re-establishment of PDU Session due to UP Path failure
Taught in 18. Being served by somebody else's network (The 5G system architecture, in depth), 27. Overload, energy, deployment and the rest (The 5G system architecture, in depth).
For the deployment scenario where the H-UPF of HR PDU Session is deployed nearby VPLMN, if the H-SMF receives from H-UPF the UP Path failure report for the path between the H-UPF (PSA) and V-UPF, the H-SMF acts as described in TS 23.527 [210]. If the H-SMF decides to delete the PDU session contexts associated with the path in failure as described in TS 23.527 [210], the H-SMF can trigger release of the HR PDU Session as described in clause 4.3.4.3 of TS 23.502 [3] and include an existing cause value indicating that a PDU Session re-establishment is requested. During the new HR PDU Session re-establishment, a new H-UPF and possibly new DNS server information (and DNS security information) are selected based on operator policy.