The number of octets of multicast packets that have been
sent on the interface, including framing characters. This
object is similar to ifOutOctets in the Interfaces MIB,
except that only multicast packets are counted.
Discontinuities in the value of this counter can occur at
re-initialization of the management system, and at other
times as indicated by the value of
hwIpMcastInterfaceDiscontinuityTime.