[SR-Users] about syn_branch

[Juha Heinanen]

Jiri Kuthan writes:

> What is "proper value"?

jiri,

according to rfc3261 section 20.42:

For implementations compliant to this specification, the value of the branch
parameter MUST start with the magic cookie “z9hG4bK”, as discussed in
Section 8.1.1.

it is sad if sr is not BY DEFAULT rfc3261 compliant.

> > 1) according to core cookbook, syn_branch core param only affects
> > stateless forwarding.  in my config, all acks are t_relayed, i.e.,
> > syn_branch param should not have any effect, but is does.  how is that
> > possible?  is there a bug in core cookbook?
> 
> In fact, ACK is forwarded statelessly  even when INVITE is processed
> using TM.

then perhaps it would be a good idea to mention this in core cookbook.

> > 2) should t_relaying of acks to 200 oks use proper (i.e.. non 0)
> 
> Not sure what "proper" would be, as the branch parameter doesn't
> play any role for matching messages neither downstream nor
> at SR. We can make it "look better" but I'm wondering if it would
> improve something.

see above.  we have seen rfc3261 sip user agents that don't understand
branch=0 value and matching of ack fails.  so instead of doing full md5
calculation, it would make sense to use rfc3261 compliant constant
rather than 0.

-- juha