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