Hi Kchitiz, As per my understanding this will be implementation dependent there is no specific standards, if client fqdn is resolving in two ip then it must be trying to load balance. In A query response both Ip should have been received therefore both of them should be compared with layer 3 ip to check the correct one for sending the responses.
Sent from Iphone, Varun > On 19-Sep-2014, at 22:35, Kchitiz Saxena <kchitiz.sax...@gmail.com> wrote: > > No Vivek, its definitely not NAT. It is 2 IP addresses in DNS server for a > hostname. > > On Fri, Sep 19, 2014 at 7:50 PM, Vivek Talwar <vivek.tal...@globallogic.com> > wrote: > >> Hi, >> >> I think since address B is different from address A, client should >> treat this as some NAT is in place should send responses back to address A >> which is actual source IP received in Packet. Here, client can also treat >> that Layer 3 ip and layer 2 ip are different and thus same logic of NAT >> should be applied and response should be sent to source IP. >> >> Refer NAT detection procedures for more details. >> >> Thanks and Regards, >> Vivek >> >> >> >> On Fri, Sep 19, 2014 at 6:23 PM, Kchitiz Saxena <kchitiz.sax...@gmail.com> >> wrote: >> >>> Hi >>> This is related to UAS behaviour to know "Where to send response for the >>> received request". Following two statement looks a bit contradicting to >>> me - >>> >>> 1. RFC 3261, Section 18.2.2 - The server transport uses the value of the >>> top Via header field in >>> order to determine where to send a response. >>> Same section, last bullet - >>> Otherwise, if it is not receiver-tagged, the response MUST be >>> sent to the address indicated by the "sent-by" value, using the >>> procedures in Section 5 of [4]. >>> >>> 2. RFC 3263 - A server, according to RFC 3261 [1], will send a response on >>> the >>> connection it arrived on (in the case of reliable transport >>> protocols), and for unreliable transport protocols, to the source >>> address of the request, and the port in the Via header field. >>> >>> As per RFC 3263, it seems like only port is used from Via header and >>> source >>> address is used. Although, I believe that Address and port both should be >>> used from Via header and RFC 3261 also indicates the same. Does this >>> statement from RFC 3263 applies to some special situations? >>> >>> >>> My problem is following- >>> Application receives an INVITE message from source IP address A with FQDN >>> in Via header. FQDN is resolved through DNS A query and receives DNS reply >>> where IP address B is mentioned at top and IP address A is mentioned after >>> that. So, all the responses are sent to IP address B. Calling side keeps >>> retransmitting the request from source address A and call does not go >>> through. Is there anything which can be changed in application's >>> behaviour? >>> >>> Thanks >>> Kchitiz >>> _______________________________________________ >>> Sip-implementors mailing list >>> Sip-implementors@lists.cs.columbia.edu >>> https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors >> >> >> >> -- >> >> Name | Title >> GlobalLogic >> P +x.xxx.xxx.xxxx M +x.xxx.xxx.xxxx S skype >> www.globallogic.com >> <http://www.globallogic.com/> >> http://www.globallogic.com/email_disclaimer.txt > _______________________________________________ > Sip-implementors mailing list > Sip-implementors@lists.cs.columbia.edu > https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/mailman/listinfo/sip-implementors
