What is Routing

A router connects with the different networks to share the data and resources. To route a data packet towards it destination a router requires the IP address of the destination, best possible routes towards the destination and the maintaining the routing information. Routing is the process of sorting and forwarding the data packets to their destinations based on their IP addresses. Routing moves the information from the source to the destination in the internetwork.

The process of routing defines the different similar tasks such as choosing the best possible shortest path and forwarding the packets based on their destination addresses. The routing table maintains the routes to the different network destinations.

The construction of the routing table is very important in the process of routing. There are two types of the routing static and dynamic.  In the static routing the routing tables of the routers are updated and maintained manually and it is best for the small networks.  In the large WAN networks, the routing is managed dynamically through the routing protocols that create and maintain the routing tables automatically. Routers compare the metrics to choose the best possible shortest path for the data packets.

A router creates a picture of the network topology by analyzing the routing tables of the other routers in the network. Dynamic routing works fast than the static.  Routing process differs in the packets delivery process.

Unicast:  Message is delivered to a single specified node.
Broadcast:  Message is delivered to all the nodes in a network.
Multicast:  Message is delivered to a group of nodes in a network.
Anycast:  Message is delivered to the node that is nearest to the source.

There are different routing protocols and some of the interior routing protocols are RIP, OSGP, IGRP and EIGRP.  The exterior routing protocols are EGP, BGP and CSPF. Routing protocols specifies that how routers communicate with each other in the internetwork to transfer the data.  There are three types of the routing protocols link state routing protocol, path vector protocols and distance vector routing protocols.

A router selects the best possible shortest path which is based on the number of metrics such as bandwidth, delay, path cost, hop count, load, reliability and the communication cost.  The routing table stores the best possible routes.