Hi Kchitiz,
Concerning your question, you skipped the first part of section 18.2.2
bullet 3 (assuming UDP). If first part of bullet 3 is successful, the UAS
does not need to resolve the sent-by FQDN.
o Otherwise (for unreliable unicast transports), if the top Via
has a "received" parameter, the response MUST be sent to the
address in the "received" parameter, using the port indicated
in the "sent-by" value, or using port 5060 if none is specified
explicitly. If this fails, for example, elicits an ICMP "port
unreachable" response, the procedures of Section 5 of [4]
SHOULD be used to determine where to send the response.
-----
From: Kchitiz Saxena [mailto:kchitiz.sax...@gmail.com]
Sent: Friday, September 19, 2014 9:49 AM
To: Brett Tate
Cc: sip-implementors@lists.cs.columbia.edu
Subject: Re: [Sip-implementors] UAS behaviour for sending responses
Hi Brett
Thanks for the reply, can you please clarify it a bit more.
Yes, there is no maddr in Via header received. When UAS resolves FQDN
mentioned in Via header, it receives the "other"(Looks like UAC has 2
entries in DNS server for this hostname) IP address at top. Hence it sends
responses back to the other address. Do you mean that UAS should somehow
send responses to both addresses received in DNS reply? UAC is not accepting
responses at "other" IP.
Thanks
Kchitiz
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