[systemd-devel] systemd-networkd mtu configuration for veth via netdev file

[Zalewski, Lukasz]

Hi list

What is the recommended way to configure mtu for veth pairs via systemd-networkd?

From https://www.freedesktop.org/software/systemd/man/systemd.netdev.html MTUBytes for veth is supported in the 
[NetDev] configuration, however given the following foo.netdev file:

[NetDev]
Name=foo
Kind=veth
MTUBytes=9000

[Peer]
Name=bar

it looks like the relevant mtu does not get set for the peer, i.e.
11: bar at foo: <BROADCAST,MULTICAST,M-DOWN> mtu 1500 qdisc noop state DOWN group default qlen 1000
    link/ether 06:93:0c:33:db:64 brd ff:ff:ff:ff:ff:ff
12: foo at bar: <BROADCAST,MULTICAST,M-DOWN> mtu 9000 qdisc noop state DOWN group default qlen 1000
    link/ether 7e:75:6d:ba:ae:ae brd ff:ff:ff:ff:ff:ff

Is it possible to set the mtu for the peer via the .netdev files, or should the .network files ([Link] section) be used instead?

For tun, or tap devices the docs explicitly mention the above approach, but not for veths.

I’m using systemd 245 (245.4-4ubuntu3.7).

Regards

Lukasz