I agree with Robert. B2BUAs should decrement Max-Forwards when they are 
forwarding requests like a proxy does. I think the only case in which they 
might reset it would be a situation like a PBX where it is originating the call.

cheers,
(-:bob




-----Original Message-----
From: [email protected] 
[mailto:[email protected]] On Behalf Of Olle E. 
Johansson
Sent: Thursday, May 20, 2010 9:52 AM
To: [email protected] Implementors
Subject: [Sip-implementors] B2B UAs and Max-Forwards

Here at SIPit we had a test involving B2BUA's in spirals and loops and other 
dangerous situations.

Robert Sparks and I ended up with a discussion about how B2BUA's should handle 
Max-Forwards.

http://tools.ietf.org/html/draft-marjou-sipping-b2bua-01
The BCP draft clearly says that B2BUA's should RESET the Max-Forwards header.

"Max-Forwards   R      Reset Max-Forwards when creating requests [3]"

In appendix A.

Robert meant that if we do NOT decrement max-forwards with one as we set up the 
new call, we will cause endless loops.

I'm stuck in between. In some situations, like a PBX, the new call is really a 
new call. When using a B2Bua as an SBC, we do forward calls.

What do you think?

/O
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