said sub step in {HEAD ~ step} further comprises determining {TAIL ~ the survivability characteristics} of the modified network topology; and 
said sub step in { HEAD ~ step } further comprises determining { TAIL ~ the survivability characteristics } of the modified network topology ; and
OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD OTH OTH OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH