{TAIL ~ A network} includes {HEAD ~ a source} of multicast packets in a multicast session and a plurality of multicast recipients in that session 
{ TAIL ~ A network } includes { HEAD ~ a source } of multicast packets in a multicast session and a plurality of multicast recipients in that session
TAIL TAIL TAIL TAIL TAIL TAIL OTH HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH