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