The value of tmnxVdoIfMcastSvcId specifies the multicast service to
be used for sending replies in the multicast service instance. In
situations where multicast and unicast are carried in separate
service instances, the value of this object should be set on the
unicast video interface to form an association with the multicast
service.
The default value of this object is same as the value of corresponding
TIMETRA-SERV-MIB::svcId.