[Spce-user] SIP UDP packet fragmentation breaking calls

Marco Teixeira admin at marcoteixeira.com
Mon Sep 21 17:27:45 EDT 2015

Hi there,

I might have stumbled upon the issue described here (but without any ALG in
the middle, just for example, as i can't pass any sensitive info here)

I'm seeing fragmented SIP packets when the final gateway sends OPTION back
over 2 NGCP CE and over to a final farm of SIP servers...

The call is established correctly and only when the OPTIONs don't get ACK,
the call drops within 10 seconds (always).

So, according to the test on that link, trancript below:
(..) If a request is within 200 bytes of the path MTU, or if it is larger
   than 1300 bytes and the path MTU is unknown, the request MUST be sent
   using an RFC 2914 [43] congestion controlled transport protocol, such
   as TCP. (...)

Shouldn't SIPWISE activate TCP or whatever to avoid this ?
How did you guys solve this ?
(no, TCP on all calls is really asking for trouble on the call volume i'm
aimming for)

Best regards
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