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