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Apply non 1500 byte default MTU to VNs

Contrail Networking Release 21.4.L3 supports and implements MTU property within tenant and virtual network resources based on the priority from highest to lowest as follows:

  1. Explicitly defined virtual network MTU, if provided
  2. Per-tenant defined default MTU, if virtual network MTU is not defined explicitly
  3. Default 1500 bytes, if no MTU is set per-tenant

The per-tenant MTU value can be configured and updated without impacting Contrail's current default behaviour. The default MTU per-tenant is 'None' and a default 1500 bytes MTU is assigned to any new virtual network for which no new explicit MTU is defined.

If a virtual network is created with zero MTU, then the MTU specified at the time of creating virtual network is is assigned. In case, MTU is not specified then its default value is applied.


Only Contrail Command user interface supports this feature.

Note: If a VN is created with MTU as 0, project MTU will be assigned to VN if specified else default MTU will be assigned