Submitter's message This contribution updates IPNNI-2026-00096R000 to more fully describe the ALIII route discovery and NNI call-establishment procedures in Section 5. The main changes include the following:
The FQDN obtained from the TN Routing Service is renamed Routing Domain. This better aligns the terminology with IETF usage, including RFC 3263, and distinguishes the domain name returned by the TN Routing Service from the SIP Endpoint FQDNs obtained from DNS SRV processing.
The route discovery procedure is reordered to better align with RFC 3263. First, the OSP constructs the TSP SIP URI of the called TN using the Routing Domain and other routing parameters obtained from the TN Routing Service. Second, the OSP applies the RFC 3263 DNS SRV procedures to that SIP URI to identify candidate TSP SIP Endpoint FQDNs and ports. Third, the OSP selects a TSP SIP Endpoint FQDN and resolves it to one or more IPv6 addresses using DNS AAAA resolution.
The update also clarifies that the SIP URI containing the Routing Domain is populated in the INVITE Request-URI. The selected SIP endpoint FQDN and port obtained through SRV and AAAA resolution do not replace the Routing Domain in the INVITE Request-URI. Instead, the selected IPv6 address and port are used as the transport destination for the mTLS connection used to carry SIP signaling between the OSP and TSP.
This contribution partially updates the Overview material in section 4 to align with the above -- more updates are needed.
-- David Hancock