The value of tmnxSubProfEgrEncapOffset specifies
the fixed packet offset.
This fixed packet offset will be used in the adjustment of the
subscriber aggregate rate, to account for the fixed offset and per
packet variable expansion of the last mile for the specific session
used by the subscriber host.
If the value of the object tmnxSubProfEgrEncapOffsetMode is equal to
'none', the offset is ignored.
If the value of the object tmnxSubProfEgrEncapOffsetMode is equal to
'auto', the offset is used as a default value for automatic learning.