How do I determine the best MTU for an IPv6 network?

General system Newbie
1

I usually set the highest MTU allowed by my router in the NetworkManager. But if I want to check for IPv6 setting the MTU seems to be not so obvious…

Any value higher than 1444 seems to be problematic but it’s ridiculous because IPv4 MTU goes as high as 1464.

 ping6 -c 4 -M do -s 1446 2620:fe::fe
PING 2620:fe::fe (2620:fe::fe) 1446 data bytes
ping6: local error: message too long, mtu: 1492
ping6: local error: message too long, mtu: 1492
ping6: local error: message too long, mtu: 1492
ping6: local error: message too long, mtu: 1492

--- 2620:fe::fe ping statistics ---
4 packets transmitted, 0 received, +4 errors, 100% packet loss, time 3053ms

So how can I determine the best MTU for an IPv6 (also IPv4) network?

2

Recommended value is 1500

3

That’s what I did and I think page loading has improved.

4
1 Like
5

Only my ISP provided ONT works for my connection. It’s MTU maxes out at 1500. So that is what I chose.

6

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