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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I m p r o W a r e A G – Leiter Commerce Kunden