[Spce-user] Udp to Tcp sig generates big mtu making the messages to fail

[Daniel Grotti]

Hi,
looks like you have a device in the middle with a small limit of mtu
that cause that fragmentation.

Daniel




On 04/28/2014 10:25 AM, Daniel Grotti wrote:
> Hi,
> A pcap trace would help, anyway, it looks like an Asterisk behavior:
> 
> http://www.spinics.net/lists/asterisk/msg123908.html
> 
> Do you have a pcap to analyze the re-invite's MTU ?
> And don't see such a lot of headers, just a couples od Record-Route and
> Via, SDP also doesn't contain any additional lines.
> 
> 
> Daniel
> 
> 
> 
> 
> On 04/27/2014 10:19 AM, Cosmin Nistor wrote:
>> Hello list,
>>
>> New to the list - maybe i could get an opinion on an issue i am facing
>> using a setup with Sipwise CE.
>> Using 2.8, 3.0 versions, tested on the 3.2.1 on a test machine, the same.
>>
>> Setup and problem description( see attached file):
>>
>> - running Sipwise in the front doing sig( tcp) to uac and sig udp to
>> asterisk + rtp and an Asterisk in the back doing sig udp.
>> - uac1 calls uac 2, the calls gets answered, uac2 sends bye;
>> - when bye is received by asterisk it sends an invite back( strange
>> behaviour to me, but since asterisk is a b2bua may be legit to try to
>> get the media back if there are any further steps to pass in the
>> dialplan before sending the final bye);
>> - Sipwise receives the invite from asterisk (udp) and passed the invite
>> to uac( tcp) < here the trouble occours, the invite is a large packet
>> that gets fragmented; the result is that down the line the uac does not
>> ack the re-invite, so the call gets stuck.
>> - using the same scenario but for the call leg Sipwise-uac using udp or
>> tls i see the same call flow but the mtu of frames is less than 1500 =>
>> packets are not fragmented => calls end ok.
>>
>> I attach a ngrep trace to show the issue, a pcap contains sensitive
>> information( ip, usernames).
>>
>> The approach could be to stripe down the size of the packets, been
>> trying to toggle parameters in sems white/blacklist but could not find a
>> working solution > if i could find some suggestions would be appreciated.
>>
>> Thanks and regards,
>>
>> Cosmin
>>
>>
>>
>>
>>
>>
>>
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> 
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