ROUTING PROTOCOL

ROUTING PROTOCOL
A Protocol is a set of rules.

A routing protocol specifies how routers communicate with each other, disseminating information that enables them to select routes between any two nodes on a computer network. Routing algorithms determine the specific choice of route. Each router has a prioriknowledge only of networks attached to it directly. A routing protocol shares this information first among immediate neighbors, and then throughout the network. This way, routers gain knowledge of the topology of the network.

Although there are many types of routing protocols, three major classes are in widespread use on IP networks:

• Interior gateway routing via link state routing protocols, such as OSPF and IS-IS
• Interior gateway routing via path vector or distance vector protocols, such as IGRP and EIGRP
• Exterior gateway routing. The Border Gateway Protocol (BGP) is the routing protocol used on the Internet for exchanging traffic between Autonomous Systems.

Some versions of the Open System Interconnection (OSI) networking model distinguish routing protocols in a special sublayer of theNetwork Layer (Layer 3).