Re: [Users] oVirt 3.4 - MTU Override not honoured by virtual NICs

----- Original Message ----- >> This sounds like a reasonable behaviour since there is a clear separation >> between the host networking configuration to the vms networking >> configuration. >> What you're attempting to achieve is guest-os level network configuration >> which >> isn't controlled by the ovirt-engine. > If I understand this correctly the the VMs NIC is mapped to a Virtual > Nic in the Host with a similar MAC, created when the VM starts. > > # VM internal NIC > eth1 Link encap:Ethernet HWaddr 00:1A:4A:2F:D2:A8 > inet addr:192.168.43.15 Bcast:192.168.43.255 Mask:255.255.255.0 > inet6 addr: fe80::21a:4aff:fe2f:d2a8/64 Scope:Link > UP BROADCAST RUNNING MULTICAST MTU:9000 Metric:1 > RX packets:6 errors:0 dropped:0 overruns:0 frame:0 > TX packets:7 errors:0 dropped:0 overruns:0 carrier:0 > collisions:0 txqueuelen:1000 > RX bytes:468 (468.0 b) TX bytes:578 (578.0 b) > > # Host Virtual Nic > vnet26 Link encap:Ethernet HWaddr FE:1A:4A:2F:D2:A8 > inet6 addr: fe80::fc1a:4aff:fe2f:d2a8/64 Scope:Link > UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 > RX packets:8 errors:0 dropped:0 overruns:0 frame:0 > TX packets:6 errors:0 dropped:0 overruns:0 carrier:0 > collisions:0 txqueuelen:500 > RX bytes:648 (648.0 b) TX bytes:468 (468.0 b) Tap should definitely have the same MTU as the bridge it's started on. > > As you can see the MTU differs between the two. If setting the MTU of > vnet26 to match the VM;s internal nic (and the host physical NIC for > that matter), everything is back to normal. > > I'm quite sure that nic (vnet26) must match what is set on the host > physical NIC, I cant see how it would work otherwise. You are correct, can you please open a bug for it? Also please specify libvirt/vdsm/kernel versions that you're using (maybe it was already fixed in updated version?)