[Users] CPU load, ERROR: append_branch: max nr of branches exceeded, etc..

Klaus Darilion klaus.mailinglists at pernau.at
Thu May 24 08:23:08 CEST 2007


Hi Dan!

Some descriptions inline ...

Dan Mechanic wrote:
> Forgive me if this question is a little open-ended...  I am new to openser
> and sip, and trying to learn all I can...
> 
> I am looking for information regarding:
> ERROR: append_branch: max nr of branches exceeded

Branches are used by openser for parallel forking. This means a incoming 
request will be forwarded to maximum MAX_BRANCHES in parallel.

> I understand that this error can be avoided by increasing the value of
> MAX_BRANCHES and recompiling openser, but, I am curious as to what happens
> when this error has been reached.
> 
> Here's our situation... We use openser, and have a separate openser presence
> server.  We had a situation recently where it seemed our presence server was
> bombarding our proxy to the point where the load on the proxy jumped and
> phones became unusable.  Taking down the presence server seemed to alleviate
> the troubles.

The > ERROR: append_branch: max nr of branches exceeded
has nothing to do with high load over overload at the traffic. (But of 
course the overload could have the same reason as the exceeding of 
max-branches).

> Also, we have an intermittent issue with phone reboots and lost calls,
> particularly on extensions that are on more than 12 phones (MAX_BRANCHES is
> currently set to 12).

Maybe the phones can't handle the 12 contacts in the 200 OK reply of the 
REGISTER.
> 
> So, my question is, is this failure (max nr of branches exceeded) an
> innocuous one?  or could it lead to futher failures (and maybe sip message
> recents... thus the bombardment)...  Are there known side affects of this
> failure?

Usually this means that either:
- bad config where you accidentally add too much branches
- you have phones which re-REGISTER before the old registration is 
expired and openser can not match the new registration to an old 
registration - e.g if the call-id in the REGISTER changes ...

Thus I guess the problem happens because your phones reboot and doing a 
new registration.

Thus, the phones should be fixed.

You can also try to tweak max_contacts
http://www.openser.org/docs/modules/1.2.x/registrar.html#AEN199
and desc_time_order
http://www.openser.org/docs/modules/1.2.x/usrloc#AEN252



> 
> Any info would be appreciated.
> 
> Thanks Much!
> 
> Best,
> Dan Mechanic
> 
> 
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