On 15.11.2010 15:26, Stefan Sayer wrote:
Hi Greger,
Greger Teigre wrote:
Hi,
I'm looking at using SBC app to replace the b2b_connect app. Looks
really good! I use it for among other things to filter out SDP
offers between a video network and a PSTN gateway. It looks like the
second
is the codec blacklist enough, then? or would it make sense to be able
to blacklist media types (video) completely?
Well, interesting question. I have used whitelisting so far, as I know
what the gateway supports. Now, theoretically, the gateway should have
been able to handle any codecs and successfully negotiate to voice only
without a signaling b2bua. However, we have little things like forked
calls and session timer to small and proprietary extensions in the
Require header, both resulting in a failed PSTN call, while the forked
call continues elsewhere resulting in no parallel forking to the PSTN...
So, I need to catch the session timer and return an error before forking
the call, then I block the Require in the sbc app (yeah, bad practice, I
know) and finally, by applying a whitelist to the codecs, I get the SDP
size down below the gateway's SDP buffer, thus avoiding the Message too
big :-)
So, I don't think media type blacklisting would really help me in this
case. However, there may be gateways supporting higher quality audio
codecs, while some don't and a media type whitelist/blacklist would
probably allow a single profile to be used in the sbc app instead of one
per capability set. Certainly not worth the work for my case.
call leg does not re-calculate body length correctly (I also just
tried the latest trunk), so even though the SDP looks good, the
gateway rejects the INVITE with Message too big. This is probably an
easy fix, Stefan, so instead of me fumbling around in the code... :-)
this is strange; the content length header is actually recalculated
every time a request is sent with body, and I haven't been able to
reproduce it (even with large messages). are you sure that it is SEMS
who doesn't set it properly? If yes, can you send (to list or PM) me
an ngrep/tcpdump plus the sdpfilter line so I can possibly reproduce
it here?
Hm, now I'm not able to replicate after pulling the latest repository
changes, i.e. it works as expected! I have changed some other things as
well, I use kamailio as a front-end and outbound proxy, so maybe it was
the offender... (I cannot see how though). I'll let you know if I'm able
to replicate it, but let's assume it was a stray fork or something :-)
BTW, I also had to increase the BUFFER_SIZE (default 2048) , the SDP
is close to 2200.
you are right, nowadays with video everywhere we should probably give
it 4k room.
Thanks!
g-)
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