❦ 27 juin 2019 19:29 +02, "Marc Roos" <M.Roos@xxxxxxxxxxxxxxxxx>:
> I can do a ping -M do -s 9000 between hosts via the vlan interface
> eth0.v101. That is as expected.
>
> The ping -M do -s 1500 macvtap0 and another host or macvtap1 fails. The
> maximum size that does not fragment is 1472.
> That is 28 bytes??? Where have they gone? I am only using macvtap, can
> this be the combination of the parent interface being a vlan and that
> macvtap is not properly handling this? Anyone experienced something
> similar? Or can explain where these 28 bytes go?
The "-s" parameter specifies the size of the ICMP payload. You need to
add 8 bytes for the ICMP header and 20 bytes for the IP header. So, 1472
is expected with a 1500 MTU. What's not expected is 9000 on a 9000 MTU.
--
Write clearly - don't be too clever.
- The Elements of Programming Style (Kernighan & Plauger)
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