[SIPForum-discussion] Hi

[Harbinder Singh]

Also, more explanation in line:--

-----Original Message-----
From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of Singh, Indresh
(SNL US)
Sent: Friday, March 30, 2007 10:58 AM
To: Taduru Hariprasad; discussion at sipforum.org
Subject: Re: [SIPForum-discussion] Hi

 

-----Original Message-----
From: discussion-bounces at sipforum.org
[mailto:discussion-bounces at sipforum.org] On Behalf Of Taduru Hariprasad
Sent: Friday, March 30, 2007 5:20 AM
To: discussion at sipforum.org
Subject: [SIPForum-discussion] Hi

Hi,

I started to learn sip. Currently going thru rfc 3261. Can i have th
answers for the
following doubts.

1) BRANCH and CSeq parameters will get change for every transaction?

>> Yes. 
----For example, in a call: Each successive request during a call will
have a higher CSeq number. Also, the caller and the called parties each
maintain their own separate Cseq counts.

2) How Ack is treated as one transaction if the final response is 200-ok
for
   an INVITE?

>> Yes. But it is a unique transaction and it's cseq is same as
INVITE-200OK. Just the branch-identifier is different.

---- INVITE is the only method in SIP in which there is this three-way
handshake involving ACK. All other SIP requests are of the form
REQUEST/200 or REQUEST/4xx or 5xx or 6xx for a failure. That is why ACK
has the same Cseq number as the other two - INVITE and 200.

3) How to detect loops and overcome them?

>> By checking if the ipAddress of your box is there in one of the i/c
via headers. But after this you have to differentiate between loop and
spiraling before you can say loop detected. 

And also please mension/attach the docs if you have for my referrence.

>> Everything in RFC-3261 :)

Thanks
Hari
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