{HEAD ~ The traditional OSPF recovery} is based on calculating {TAIL ~ new shortest paths} from a node to all the destinations in the changed topology 
is based on calculating
{ HEAD ~ The traditional OSPF recovery } is based on calculating { TAIL ~ new shortest paths } from a node to all the destinations in the changed topology
HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD REL REL REL REL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH