Brian May <brian@microcomaustralia.com.au> wrote:
At Julien Goodwin's talk in April, he said, if I understand correctly, Internode has a bug in their implementation of PPPoA and IPv6 in that 1500 size packets will get silently dropped. Only for IPv4, not IPv6.
It's happening for IPv4 here as well as IPv6. I have to set my MTU to 1496 bytes on ppp0. The symptom was that calls made to Internode's Nodephone service from my FreeSWITCH installation failed - that is, SIP packets were dropped on the way out. Setting MTU to 1496 was enough to solve it. I just tested again: ip link set mtu 1500 dev ppp0 called a Nodephone test number - no connection. ip link set mtu 1496 dev ppp0 Repeated the call - it worked. When originally diagnosing the problem, I ran pings of different sizes and verified the cause.