The same logic which I sent in my earlier mail applies for stateless proxy also...Whereas the forking wound not be applicable for stateless proxies.. Thanks & Regards, Nataraju A.B. -----Original Message----- From: Sukumar R [mailto:[EMAIL PROTECTED] Sent: Friday, November 11, 2005 4:32 PM To: [email protected] Cc: [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL PROTECTED] Subject: Re: [Sip-implementors] RE: Loop detection in SIP Hi, If it is a state-less proxy, then how the loop would be detected? regards, Sukumar R.
--- Begin Message --- Title: RE: [Sip-implementors] RE: Loop detection in SIP[ABN] Proxy can opt to compare those headers separately, but in that
case, proxy has to do that many comparisons for every request it
proxies. This would be CASTLIER. To avoid too many comparison for a
simple task, an hash of the req-uri, route, record-route and other
headers affecting the request routing.Hence with a single comparison we can identify that particular request
has been looped or spiraled through....Thanks & Regards,
Nataraju A.B.-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]] On Behalf Of
[EMAIL PROTECTED]
Sent: Thursday, November 10, 2005 6:02 PM
To: [EMAIL PROTECTED]; [email protected]
Subject: RE: [Sip-implementors] RE: Loop detection in SIP
If in case of spiral, anyway one of the header fields would have changed
then why can't proxy simply look at the header fields and clasiify the
request as spiral or Loop( assuming that Via header has proxy's
address).
Why do we need to go through Branch Id here?________________________________
From: Ajit Kumar [mailto:[EMAIL PROTECTED]]
Sent: Thu 11/10/2005 4:51 PM
To: Naveen Kak (WT01 - Voice & Next Generation Networks);
[email protected]
Subject: RE: [Sip-implementors] RE: Loop detection in SIP
Branch parameter placed in the via has two parts in which the second
part is used for loop detection, this part is calculated by hashing
various headers of the request, now if the request is getting looped
than this part of the branch parameter calculated by the proxy will
match the corresponding part of the branch parameter already placed in
the one of the via field but if it is spiraling than the one calculated
and the one already in the via header will be different.
The basic thing is that in looping the routing information ( i.e. the
headers used to calculate the second part of branch parameter) don't
change, while in spiraling one or more of these header fields changes
changing the hash value.Regards
Ajit-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]] On Behalf Of
[EMAIL PROTECTED]
Sent: Thursday, November 10, 2005 3:40 PM
To: [email protected]
Subject: [Sip-implementors] RE: Loop detection in SIP
Hi Guys,
Request a response ASAP.Thanks in Advance
Naveen________________________________
From: Naveen Kak (WT01 - Voice & Next Generation Networks)
Sent: Thu 11/10/2005 3:33 PM
To: [email protected]
Subject: Loop detection in SIP
________________________________
Hi,
Can anybody expain me how looping is detected by the Proxy.
I know that if the proxy finds its address in the Via header, it means
it has forwarded the request before.But then how branch ID is used to detremine that its a loop or
spiral(The RFC says it does a hashing of the Branch Id and also that of
the Request URI and compares both).Could somebody simplify this for me( how excatly is branch ID is used in
this context).
Thanks
Naveen
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