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