The type of virtual interface desired by the network manager.
If and when a row is created in this table by using a SetRequest
to cvifRowStatus, the corresponding ifTable row will be created
by the agent with its ifType as specified by this object.
Note that agents are unlikely to support more than a few values
for this object, e.g., 'ethernetCsmacd(6)' and
'fibreChannel(56)'.