[asterisk-users] Asterisk PJSIP setting don't fragment bit on UDP

[Benoit Panizzon]

Hi Gang

I noticed, that when I enable multiple codecs and rtp encrypting
(generating a large SDP) invites with credentials do not get through
anymore.

So sniffed the connection and found that the IP packets have the don't
fragment bit set, causing a VDSL router with 1472 MTU in the path to
reject them.

So it asterisk or the underlying OS the culpit?

nping --udp -g 5070 -p 5060 registrarIP --data-length 1472

sniffing both sides. nping issues packets without don't fragment bit.
Router fragments them, registrar receives two fragmented packets per one
sent packet.

So I guess it's asterisk which forcefully is setting don't fragment.

But I could not find any such setting regarding SIP.

Did I miss something? How do I make asterisk not set the don't fragment
bit on UDP?

Mit freundlichen Grüssen

-Benoît Panizzon-
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