[SR-Users] about rtpengine-[offer-answer] via-branch flag

[Sebastian Damm]

Hi,

On Tue, Jul 18, 2017 at 9:42 AM, Juha Heinanen <jh at tutpro.com> wrote:
> Is the note about "serial forking" correct or should it be about
> "parallel forking" instead?  In case of serial forking, it would not
> matter if the whole call is deleted, because a new offer would be issued
> for the next branch.  Or perhaps I just don't understand the meaning of
> the note?

If the proxy that does the parallel forking is the same that issues
the rtpengine call, it shouldn't matter because there won't be a
delete command for the cancelled branch. If you have a scenario where
the proxy sends out multiple branches and for example a load balancer
does the rtpengine stuff, then the load balancer should use the via
branch flag or the cancelled branch will kill the call.

In serial forking, the new INVITE could go out before the CANCEL is
sent out. If that happens, the Via branch is needed to not kill the
whole call.

So one can think of scenarios with both serial and parallel forking,
where the via-branch flag can be useful.

Regards,
Sebastian