[SIPForum-discussion] To-Tag in REGISTER message

[Vijay Badola]

In addition to other answers given by others, loop detection is found when the same request comes at same sip node again without getting final answer (then we check whether its loop or not). The case you are talking about First request is already answered, so as per my understanding, in  any case request  will not be responded with 482 response code by the server who has already created final answer for earlier request (although SIP node may ignore the request if you try to send request with same parameter in new request, which will never be the case I think).

,Regards
Vijay Badola
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From: discussion-bounces at sipforum.org [mailto:discussion-bounces at sipforum.org] On Behalf Of Keerthi Srinivasan
Sent: Tuesday, October 30, 2012 4:48 PM
To: sip-implementors at lists.cs.columbia.edu; discussion at sipforum.org
Subject: [SIPForum-discussion] To-Tag in REGISTER message

All,

When UA sends REGISTER request to the server it does not contain the To-Tag and Server is accepts the Registration (200 OK) will have the To-Tag.

If the Refresh or Deregister does not have the To-Tag in the REGISTER message. Is the server will accept the Refresh or Deregister REGISTER message or will send 482 Loop Detected as per the RFC3261 (8.2.2.2 Merged Requests)

Here is the RFC3261 content:
8.2.2.2 Merged Requests

   If the request has no tag in the To header field, the UAS core MUST
   check the request against ongoing transactions.  If the From tag,
   Call-ID, and CSeq exactly match those associated with an ongoing
   transaction, but the request does not match that transaction (based
   on the matching rules in Section 17.2.3), the UAS core SHOULD
   generate a 482 (Loop Detected) response and pass it to the server
   transaction.

      The same request has arrived at the UAS more than once, following
      different paths, most likely due to forking.  The UAS processes
      the first such request received and responds with a 482 (Loop
      Detected) to the rest of them.

Is the Server MUST reject or Accept the Refresh / Deregister REGISTER request?

--
Regards,
Keerthi

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