Intradomain routing protocols

Intradomain Routing Protocols Two processes, routing and forwarding, are needed to deliver IP packets over a network. The routing process determines and chooses the path to a destination based on metrics such as number of hops, delay, and throughput. The forwarding process does the actual insertion of the IP packet into a frame and forwards the frame to the next hop.

Routing Tables Every host/router in a network has a routing table. The routing table consists of the destination network address, the subnet mask, the next hop IP address, and the interface. The destination network address contains the network portion of the destination networks IP address. The subnet mask is used to identify the network address from the host address. The next hop IP address is the address where the packet will be forwarded to for delivery. The interface identifies the associated route.

Forwarding Tables IP packets are forwarded after determining the route and the next hop. This is done according to either local or remote delivery models. A local delivery model is used when the both the destination and the host are on the same local network. The IP packet is forwarded directly to the destination in a MAC frame. Remote delivery protocols are used when the destination and host are on different networks. The packet is inserted into a frame and sent to the next hop router.