[SR-Users] Increase MAX_BRANCHES_LIMIT

[Henning Westerholt]

Hi Lars,

this should be the relevant check: „sr_dst_max_branches>=MAX_BRANCHES_LIMIT“.

So, it should be 32, biggest value is then 31. I’ve added some more logging to the git master branch to also log the maximum value and verified it.

Cheers,

Henning

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From: sr-users <sr-users-bounces at lists.kamailio.org> On Behalf Of Lars Jansson
Sent: Monday, December 12, 2022 4:32 PM
To: miconda at gmail.com; Kamailio (SER) - Users Mailing List <sr-users at lists.kamailio.org>
Subject: Re: [SR-Users] Increase MAX_BRANCHES_LIMIT


Hi Daniel and Henning,

Thanks a lot for your answers, this will save me from wasting time on a dead end. 31x31 is plenty, so this is a way forward to workaround the current limitation in tm.

Just to see if I understand you correctly, Daniel, regarding the record-routing bit: At first record routing is applied as usual, but when a looped request is received and forked to targets no record routing shall be applied?

As a side note I tried setting max_branches=31, but that was not accepted, so I changed to max_branches=30. Perhaps this simply implies that the first branch is enumerated as branch #0 ?

Cheers,
Lars
Den 2022-12-12 kl. 09:04, skrev Daniel-Constantin Mierla:

Hello,

the value 32 for MAX_BRANCHES_LIMIT is a constraint of tm internals which uses a 32 bitmap for some operations, going higher will require coding in tm module.

The variant now is to loop one more through kamailio and you can get to 32x32 branches. By doing record route only on one step of looping, then you have this looping only for initial INVITE transaction, the re-INVITE, BYE, etc. will go straight.

One more note, I am not sure and no time to check the code, one bit might be reserved in the bitmap, so it can be 31x31 branches after one local loop.

Cheers,
Daniel
On 10.12.22 13:02, Lars Jansson wrote:

Hi,

I am building a configuration script where for some traffic flows parallel forking will be needed, and in this case I need to go beyond the default max limit of the max amount of branches.

Apart from this specific case the traffic load that kamailio will need to handle is very low, let's say just one second here and there with up to 5 concurrent calls at most.

This limit is as far as I understand set here: usr/local/src/kamailio-5.6/kamailio/src/core/config.h

And the default limit is:
#define MAX_BRANCHES_LIMIT              32      /*!< limit of maximum number of branches per transaction */

Here are the questions I have related to this:

1) If I increase the value of this constant in config.h, how high is it reasonable to set this value and still have a stable system?

2) If I increase MAX_BRANCHES_LIMIT beyond 32, are there also other parameters that needs to be changed for the system to be able to cope, and if so which parameters?

Regards,
Lars



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