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[Contrail] How to update the interface MTU of an exsiting VMI with DHCP option



Article ID: KB34432 KB Last Updated: 31 May 2019Version: 1.0

DHCP options can be used to provide interface MTU to VM by vrouter.  For an existing VMI, the 'neutron port-update' command can be used to update the MTU value.


By default, there is no DHCP options configued on VMI, and the interface MTU inside a VM is 1500.

If we change the interface MTU with the command "neutron port-update --extra-dhcp-opt opt_name='interface-mtu',opt_value='<mtu value>' <interface>", we can see the MTU value is changed after this interface renew its address:

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