said sub step in step further comprises determining {HEAD ~ survivability characteristics} of {TAIL ~ the current network topology} 
said sub step in step further comprises determining { HEAD ~ survivability characteristics } of { TAIL ~ the current network topology }
OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL