But you can see, what the guy described is in a dialog instead of "outside of a dialog". Please point out if I don't understand correctly.
Thanks Derrick -----Original Message----- From: Brett Tate [mailto:[EMAIL PROTECTED] Sent: 2008年5月21日 21:41 To: DING Derrick Cc: [email protected] Subject: RE: [Sip] SIP one DNS domain much IP Your understanding corresponds to a "local policy" overriding the rules of following RFC 3263. Your mentioned "local policy" has not been presented within an RFC. RFC 3261 section 12.2.1.1: "Once the request has been constructed, the address of the server is computed and the request is sent, using the same procedures for requests outside of a dialog (Section 8.1.2)." RFC 3261 section 8.1.2: "The destination for the request is then computed. Unless there is local policy specifying otherwise, the destination MUST be determined by applying the DNS procedures described in [4] as follows." > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of DING Derrick > Sent: Tuesday, May 20, 2008 9:50 PM > To: Brett Tate; 孙永光; [email protected] > Subject: Re: [Sip] SIP one DNS domain much IP > > As my understanding, A should not do DNS query without any > exception, such as 408 timeout. > > So you should define the condition for DNS query in order to > avoid the case you describe. > > Derrick > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of Brett Tate > Sent: 2008年5月20日 20:42 > To: 孙永光; [email protected] > Subject: Re: [Sip] SIP one DNS domain much IP > > Because of potential load-balancing (as you are observing), > solely using A records within primary/secondary > configurations should be avoided unless additional agreements > or configuration has been made to avoid the situation you are > describing concerning in dialog requests. The additional > agreements override typical rfc3263 behavior by applying > local policy (potentially non compliant) to remain stateful > within dialog. The potential additional configuration (to > avoid the mentioned override) is to have DNS control to avoid > automatic load-balancing/iterating concerning A records so > that the A record query/handling can always result in the > same ordered list. > > RFC 3263 discusses using DNS SRV records to more clearly > indicate prioritization and load-balancing. If SRV records > not supported, the Contact should reflect a single AS unless > the alternative locations can accommodate the situation (or > additional agreements or configuration has been made to avoid > trying the alternative locations first). > > > ________________________________ > > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of ??? > Sent: Tuesday, May 20, 2008 7:11 AM > To: [email protected]; IETF Sipping List > Subject: [Sip] SIP one DNS domain much IP > > > > Hi Guys: > > I have a question about DNS > it is that one DNS domain has much IP Addrs , eg: > as.test.net=>(192.168.2.1/192.168.2.2) > and "as.test.net: is B2B server > 1) A INVITE B , A resolves the DNS "as.test.net" > 192.168.2.1,then A sends INVITE request to > 192.168.2.1 > 2) A receives 200 response with contact "as.test.net" > and no record route > 3)A resolves the DNS "as.test.net" again, it gets > 192.16.2.2 and sends ACK to 192.168.2.2 > > now the 192.16.2.1 can't recieve the ACK request , so > the session can't be created > > Anyone can give me any advice, or some RFC/draft about it > > Thanks in advance > > Samman > 2008-5-20 > _______________________________________________ Sip mailing list https://www.ietf.org/mailman/listinfo/sip This list is for NEW development of the core SIP Protocol Use [EMAIL PROTECTED] for questions on current sip Use [EMAIL PROTECTED] for new developments on the application of sip
