On Wed, 2006-10-11 at 08:34 -0700, Sachin Danait (sdanait) wrote: [reply limited to sip-implemntors]
> I have a question regarding Section 5 (Server Usage) of RFC3263 that I > am requesting your opinion on. > IMHO, there appears to be an issue with server-side Via header > processing rules as currently specified in RFC 3263, when a Via header > of the received request sent-by address field has an SRV name (a port > is not specified on the header) and the SRV name resolves to > non-default SIP ports. > Section 5 of RFC3263 references section 18.2.2 of RFC3261, and states > that for unreliable transports, the initial response transmission sent > by a UAS should be attempted towards the source address of the > received request and the default destination port (5060) if none is > specified in the Via header. If this initial response encounters a > failure and there wasn’t any port specified in the Via, the UAS should > resolve the domain name in the sent-by field using SRV procedures, and > the response should be sent to the address and port selected based on > that SRV query. > My question is regarding the first step of the above response > processing logic. > Since SRV lookups are performed on a domain-name only when no port is > specified, this obligates the sender of a request to not encode a port > in its Via header if that sender wishes to be reachable using SRV > resolution. Consequently, this appears to imply that the sender needs > to be listening for responses on the default SIP port in addition to > any of the ports resolved from the SRV query, since the first > transmission of any incoming response will always be directed towards > the default port as per section 18.2.2 of RFC3261. I don't think so. If the name in the Via is resolvable as an SRV name, then the SRV record _does_ specify the port, so section 18.2.2 does not apply. Only if the name in the Via must be resolved as a host address lookup without SRV should the port be considered unspecified and be sent to the default well known port. -- Scott Lawrence tel:+1-781-938-5306;ext=162 or sip:[EMAIL PROTECTED] sipXpbx project coordinator - SIPfoundry http://www.sipfoundry.org/sipX Chief Architect - Pingtel Corp. http://www.pingtel.com/ _______________________________________________ Sip-implementors mailing list [email protected] https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
