Routing Protocols

Routing Protocols

A routing protocol is a set of rules or standard that determines how routers on a network communicate with each other and exchange information to enable them select best routes to a remote network, Each router has priority knowledge only of networks attached to it directly. Routers running routing protocol shares this information first among immediate neighbors, then throughout the entire network. This way, routers gain an insight knowledge of the topology of the network.

Routing protocols perform several activities, including:

* Network discovery

* Updating and maintaining routing tables

The router which sits at the base of a network maitains a routing table, which is a list of networks known by the router. The routing table includes network addresses for its own interfaces, which are the directly connected networks, as well as network addresses for remote networks. A remote network is a network that can only be reached by forwarding the packet to another router.

Remote networks are added to the routing table in two ways:

i. By the network administrator manually configuring static routes.

ii. By implementing a dynamic routing protocol.

Dynamic Routing protocols are used by routers to share information about the reachability and status of remote networks.

IP Routing Protocols

There are several dynamic routing protocols for IP. Here are some of the more common dynamic routing protocols for routing IP packets:

• RIP (Routing Information Protocol)
• IGRP (Interior Gateway Routing Protocol)
• EIGRP (Enhanced Interior Gateway Routing Protocol)
• OSPF (Open Shortest Path First)
• IS-IS (Intermediate System-to-Intermediate System)
• BGP (Border Gateway Protocol

Advantages of dynamic routing protocols

i. Dynamic routing protocols update and maintain the networks in their routing tables.

ii. Dynamic routing protocols not only make a best path determination to various networks, they will also determine a new best path if the initial path becomes unusable or there is a change in the topology.

iii. Routers that use dynamic routing protocols automatically share routing information with other routers and compensate for any topology changes without involving the network administrator.