What will happen if the UA works with outbound proxy farm, so the UA sends the INVITE to a FQDN which resolved to all the proxies in the farm. The first proxy is down so the INVITE transaction is done through the second proxy. Now the UA wants to send the ACK so it has the same FQDN as the INVITE and the ACK will go to the first proxy again. My assumption here is that UA that works with outbound proxy always sends all transaction to the outbound proxy regardless of other routing information that arrives in the 2xx on the INVITE, maybe my assumption is wrong, please advise.
Thanks in advance, David Isaac. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Dale Worley Sent: Thursday, June 16, 2005 7:01 PM To: [email protected] Subject: RE: [Sip-implementors] Resolving in ACK request 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 ______________________________________________________________________ This email message has been scanned by PineApp Mail-Secure and has been found clean. _______________________________________________ Sip-implementors mailing list [email protected] http://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
