How To Set Xen Ubuntu 18.04.3 Guest To MTU 9000

[Jan Rasche]

Hi Community,

 

I have a problem setting the MTU in a Ubuntu LTS VM to 9000.

 

Host:

[root@xs2 ~]# xe vif-param-set uuid=e096082c-71bc-0eed-8424-15e4c6fdb794 MTU 9000
Error: Field 'MTU' is read-only

VM:

backup:(/)# ifconfig
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500

backup:(/)# ifconfig eth0 mtu 9000
SIOCSIFMTU: Invalid argument


backup:(/)# ip link set eth0 mtu 9000
RTNETLINK answers: Invalid argument

 

How do I achive this?

 

(The host VLAN and bond are at 9000.)

 

Thanks, Jan

[Tobias Kreidl]

The MTU should be set on the XenSever host side, before the connection to the VM is created at which point the VM should inherit that MTU setting.

 

-=Tobias

[Jose Pablo Benavides]

Hello,

 

I guess you want to do this on you network cards.

 

You can do it at the VM network tab on Xencenter

[Jan Rasche]

@Tobias

You mean the setting on the VM is working, if it is down?
xe vif-param-set uuid=e096082c-71bc-0eed-8424-15e4c6fdb794 MTU 9000

The VLAN and Bond the VM is using are 9000 on the host already. The VM was imported and did not inherent it when created from imported template.

 

@Jose

No, I do not have it in the VM network tab. There is no MTU setting here in XenServer.

I only have this for the network tab of the host itself. There ist the MTU 9000 aready set for the VLAN and the Bond the VM ist using.

 

Best, Jan

[Tobias Kreidl]

Jan,

There must have been something weird set with the network on the VM you imported. I'd suggest deleting and re-creating the network on the VM, which should inherit the MTU of the bond setting.

 

-=Tobias