Machine manager 610 understands the physical topology of the networks and keeps track of the location of {HEAD ~ the physical machines} and virtual machines which are {TAIL ~ members} within each of the networks 
are
Machine manager 610 understands the physical topology of the networks and keeps track of the location of { HEAD ~ the physical machines } and virtual machines which are { TAIL ~ members } within each of the networks
OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH REL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH