Specifies the queueing mode at this interface.
'cos' indicates that the interface is queueing
a packet based on the CoS value of the packet.
This value can only be set if the 'cos' bit
of csqIfQueueModeCpb is set.
'dscp' indicates that the interface is queueing
a packet based on the DSCP value of the packet.
This value can only be set if the 'dscp' bit
of csqIfQueueModeCpb is set.