[SIPForum-discussion] Sip Proxy Server

[Priyankam]

If only sent by is checked it can be either loop or spiral.. but for loop
branch parameter will also match,
in case of spiral.. branch parameter will have different value.
hence to detect a loop we need to store the branch parameter of all request
that was sent via proxy.
its a hectic job.. any better way to detect a loop.
  -----Original Message-----
  From: mjhorse at qq.com [mailto:mjhorse at qq.com]
  Sent: Thursday, April 24, 2008 3:30 PM
  To: priyankam; 'prasanna c'; discussion
  Subject: Re: [SIPForum-discussion] Sip Proxy Server


  Hi

  But if all Via header is check, proxy will know for sure that if it is
already on the way of the message. So, why loop cant be detected?


  ------------------
  by mj


  ------------------ Original ------------------
  From:  "Priyankam"<priyankam at tataelxsi.co.in>;
  Date:  Thu, Apr 24, 2008 05:54 PM
  To:  "'prasanna c'"<c_prasanna_c at hotmail.com>;
"discussion"<discussion at sipforum.org>;
  Subject:  Re: [SIPForum-discussion] Sip Proxy Server

  You are trying to say if the sent-by matches loop is detected? what about
branch parameter? shouldn that also match with Via..
  One more doubt if only sent by check is done.. then it can also be spiral
detection.. in this we cant discard the request?

  Please solve these issues.
    -----Original Message-----
    From: prasanna c [mailto:c_prasanna_c at hotmail.com]
    Sent: Thursday, April 24, 2008 2:05 PM
    To: priyankam at tataelxsi.co.in; discussion at sipforum.org
    Subject: RE: [SIPForum-discussion] Sip Proxy Server


    You should check all the via headers that has sent-by value placed by
proxy in earlier forwarding to detect the loop.



--------------------------------------------------------------------------
      From: priyankam at tataelxsi.co.in
      To: discussion at sipforum.org
      Date: Thu, 24 Apr 2008 12:39:15 +0530
      Subject: [SIPForum-discussion] Sip Proxy Server


      Hi,

        we have a confusion regarding loop detection by proxy server. As per
the RFC 3261 we create key for branch parameter using , To tag, From tag,
Call-ID header
      field, the Request-URI of the request received (before translation),
the topmost Via header, and the sequence number from the CSeq header field.

      But the confusion is if the request traverses through several proxies
and the same request comes back to the previous proxy, the top most via gets
changed,
      so the Key generated will be different, hence loop detection is not
possible.

      Please suggest a solution for this issue.

      Regards,
      Priyankam
      Tata Elxsi Ltd.
      Bangalore



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