That's true, it could happend. But if you don't put IP addresses in as the hosts in Record-Route's, you should use names that preferentially resolve to the IP address of the host adding the Record-Route. Section 6 of RFC 3263 discusses a clever way to accomplish this. If done right, the chances of an attempt being made to send to a down server are greatly reduced.
Dale -----Original Message----- From: Venkatesh [mailto:[EMAIL PROTECTED] Sent: Thursday, June 16, 2005 11:33 AM To: Dale Worley Cc: [email protected] Subject: Re: [Sip-implementors] Resolving in ACK request I think this scenario happens if all the RR headers that got added by proxies were FQDN's that resolved to multiple IP addresses (per section 16.6 of 3261 this is possible, as the RR header MUST resolve to the IP address/port of this element that or a suitable stand in). On receipt of the 200 OK, the UA constructs the route set which is a set of FQDN's. It builds the ACK. It uses the Route set to send the ACK. This results in the UA having to do a DNS lookup. The response returned by DNS could result in the UA choosing an IP address/port of a proxy that is down. _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
