[SR-Users] Problem with ser - INVITE size problem tcp->udp?

[Simone Felici]

Thank you a lot for your answer!
I'll try these modifications, starting from some tune on actual config of ser-2.0 to bring all working correctly and then ending 
with a test phase of the ser-3.0 version.
I'll let you know if I should have some new issues.

Thank you!!!

Simon


Il 30/09/2010 18:02, Andrei Pelinescu-Onciul ha scritto:
> On Sep 29, 2010 at 10:43, Simone Felici<s.felici at mclink.eu>  wrote:
>>
>> Hello to all!
>>
>> I need a little help with our ser installation (ser-2.0.0-rc1).
>> The continuous groving up of our infrastructure and using even more
>> codecs, causes the INVITE (udp) to be over 1500bytes. An
>> external->incoming call to our proxy sip comes in with a size of
>> ~1300 and will be forwarded to the end device (sua) over 1500. Ser
>> is adding more than 200bytes in the udp packet. I can see 'INVITE'
>> from ser to customer, but the INVITE is not answerred due the size.
>> I'm sure about that, because in certain situations, deleting codec
>> list the packet-size goes under the 1500bytes and all works.
>> To main issue is from external calls to ser server to our customers.
>> Calls started from customers to ser and then out are all ok.
>
>
> Most likely at some point the UDP packet has to be fragmented and since
> ser 2.0 doesn't clear the DF bit on linux, the first router that has to
> do the fragmentation will just drop the packet.
>
>> Now the question: Could the passage from UDP to TCP solve the issue?
>
> It could, but it also could introduce other problems. I would use at
> least 2.1 with TCP (because of the async tcp support).
>
>> Could someone give me an example and how implement it into our ser configuration?
>> The atteched configuration, ser on a mysql basis, is working well in expect the issue described.
>
> The easiest way would be with a more recent version, either ser 2.1
> or better sr 3.0  (http://sip-router.org/tarballs/sr/sr_3.0/) or the
> soon to be released 3.1 (next week). Note however that you will have to
>   migrate the config file (but not the DB).
>
> All the version above will make sure the DF bit is clear. They also have
> automatic fallback to tcp if the packet is too big (you only have to
> set udp_mtu and udp_mtu_try_proto in the config).
>
> If you decide to stick with 2.0, then you could try reducing a bit the
> packet size, by turning off some of the options.
> For example I would add:
> - modparam("rr", "append_fromtag", 0)
> ( the fromtag is there only for debugging purposes)
> - comment out  setavpflag("$rtp_proxy_node", "dialog_cookie")
>   (since according to your config you don't use it anyway)
> - sip_warning = 0 (won't affect the INVITEs, but replies will be
>    smaller)
>
> You could also try to backport the DF fix to 2.0:
> http://git.sip-router.org/cgi-bin/gitweb.cgi?p=sip-router;a=commitdiff;h=f3a2679;hp=2aa5c1f7d7dd2132c2478df6ca36fa8bc42f09e9
> It should be quite easy, since this is only a small addition.
>
>
>
> Andrei