RIB and FIB

Hi,

RIB is derived from the control plane, it is not used for forwarding. Every protocol such as OSPF, EIGRP, BGP has its own RIB and select their best candidates to try to install to global RIB so that it can then be selected for forwarding. If this is implemented through totally separate RIBs or one big RIB with partitions I am not aware of.

FIB is used for forwarding, although this information is derived from the RIB and from adjacency tables so that the packet can be rewritten with the correct encapsulation.

I hope it helps.

Hi friend!
The routing table stores the routes discovered by various routing protocols. The routes in the routing table are classified into the following types: Direct routes, static routes, and dynamic routes.

Forwarding table (FIB): Each forwarding entry in the FIB table specifies the physical interface or logical interface that sends packets to a network segment or a host. Then, the packets can reach the next node of the path or are transmitted to the destination host in the directly connected network without passing through other devices. The matching of the FIB table complies with the longest matching principle. When the FIB table is searched, the destination address of the packet and the mask of each entry in the FIB are bitwise "logical and". The obtained address matches the network address in the FIB entry. Finally, a maximum matching FIB entry is selected to forward the packet.


Differences:
1. The RIB table does not directly guide the forwarding, but guides the generation of the FIB table. The FIB table provides guidance for forwarding, which is irrelevant to route generation.

2. FIB entries are used to guide the actual forwarding of packets on the device. The FIB entries specify the actual interface to which packets are forwarded and the interface on which packets are transmitted.

3. The routing table refers to the line problem, that is, the line scheme for transmitting data packets from one end to the other end. It does not indicate the specific interface that is forwarded by the routing device. Usually, the next-hop routing address is determined at the sending end. The FIB table is delivered to the hardware to guide forwarding. It is mainly used to determine the specific forwarding details (physical interface) rather than the line problem.
Glad to help!