RIB Vs FIB Cisco show ip route show ip cef Juniper show route 10.0.0.0/24           ← RIB (full route info) show route forwarding-table      ← FIB (active, optimized) ## Evolution 1.Process switching    Routing table (to find next hop). ARP table (to resolve next hop IP to MAC). Interface lookup . 2.Fast switching Creates a fast-switching cache entry for this destination. The cache stores: Destination IP Next-hop IP Outgoing interface MAC header to use (from ARP) 3.Modern Cisco routers use CEF , which pre-builds a complete forwarding table (FIB) and adjacency table in hardware or software — no caching needed per flow. How Router Forwards packets Protocol-DB > RIB > FIB > Forwarding table - nexthop interface, MAC  CAM - MAC,VLAN,INTERFACE (Complete match) TCAM - IP,ACL etc (Longest Match) Topology R1-----g0/0-------g0/0-----R2------g1/0---------g0/0------R3-------Lo (100.100.100.100) Configuration #R1 g0/0 - 1...