RIB, FIB, CEF, adjacency tables

dppagc

Correct me if I am wrong:

RIB-> possible routing routes
FIB -> parsed from RIB
CEF -> good info from FIB
adjacency tables ???

EdTheLad

The RIB hold all known routes learned from the various routing protocols including static or connected. These routes appear as learned i.e. with the next-hop that was provided by the routing protocol which means the route could be recursive.
The FIB holds has all routes from the RIB but it holds the results of the recursive lookup against destination ip address and points to the exit interface.
The adjacency table holds the L2 info for all directly connected neighbors i.e. the mac address of directly connected device.
CEF uses both the FIB and ADJ table to create header that can be pushed onto frames quickly as they get forwarding through the router. Rather than the router performing a recursive lookup, finding the exit interface, checking the arp cache of exit interface for remote mac etc, packet arrives for destination and gets the cef destination header added.