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

Juha Heinanen jh at tutpro.com
Tue Jul 18 09:42:23 CEST 2017


rtpengine-offer function documentation tells this about via-branch flag:

 via-branch=... - Include the “branch” value of one of the “Via” headers
 in the request to the RTP proxy. Possible values are: “1” - use the
 first “Via” header; “2” - use the second “Via” header; “auto” - use the
 first “Via” header if this is a request, or the second one if this is a
 reply; “extra” - don't take the value from a header, but instead use
 the value of the “extra_id_pv” variable. This can be used to create one
 media session per branch on the RTP proxy. When sending a subsequent
 “delete” command to the RTP proxy, you can then stop just the session
 for a specific branch when passing the flag '1' or '2' in the
 “rtpengine_delete”, or stop all sessions for a call when not passing
 one of those two flags there. This is especially useful if you have
 serially forked call scenarios where the RTP proxy gets an “offer”
 command for a new branch, and then a “delete” command for the previous
 branch, which would otherwise delete the full call, breaking the
 subsequent “answer” for the new branch.

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?

-- Juha



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