Hello R.B Kumar,
the FIB contains also information that is used for the actual forwarding of packets: for example the MAC address of the ip next-hop is needed to perform the packet rewrite function.
So you can imagine a FIB entry as:
IP subnet base address
IP subnet mask
ip address of next hop
outgoing interface encapsulation information (how to build the correct frame on the outgong interface)
for LAN interfaces you need the MAC address of the next hop, the source MAC address to be used that of the outgoing interface
for example with CEF you can see entry using sh ip cef prefix mask detailed
sh ip cef 10.34.26.64 255.255.255.240 det
10.34.26.64/28, version 744312, epoch 0, per-destination sharing
0 packets, 0 bytes
tag information set, all rewrites owned
local tag: 1031
via 10.98.192.209, FastEthernet1/0, 0 dependencies
traffic share 1
next hop 10.98.192.209, FastEthernet1/0
valid adjacency
tag rewrite with Fa1/0, 10.98.192.209, tags imposed {}
via 10.98.192.213, FastEthernet2/0, 0 dependencies
traffic share 1
next hop 10.98.192.213, FastEthernet2/0
valid adjacency
tag rewrite with Fa2/0, 10.98.192.213, tags imposed {}
0 packets, 0 bytes switched through the prefix
tmstats: external 0 packets, 0 bytes
internal 0 packets, 0 bytes
two next hops are available to reach the prefix out two different interfaces where also is used
sh ip arp 10.98.192.209
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.98.192.209 143 000e.847e.87c0 ARPA FastEthernet1/0
RT-RM-TLD066-RG-BB-E-6#sh ip arp 10.98.192.213
Protocol Address Age (min) Hardware Addr Type Interface
Internet 10.98.192.213 165 000e.843b.e3c0 ARPA FastEthernet2/0
the RIB for this prefix is
sh ip route 10.34.26.64
Routing entry for 10.34.26.64/28
Known via "isis", distance 115, metric 10011000, type level-2
Redistributing via isis
Last update from 10.98.192.213 on FastEthernet2/0, 1d20h ago
Routing Descriptor Blocks:
* 10.98.192.209, from 10.80.0.101, via FastEthernet1/0
Route metric is 10011000, traffic share count is 1
10.98.192.213, from 10.80.0.101, via FastEthernet2/0
Route metric is 10011000, traffic share count is 1
Hope to help
Giuseppe
