What are Routing Protocols?

 Introduction

In computer networking, routing refers to the process of directing data packets between different networks or nodes. The purpose of routing is to ensure that data packets are delivered to their intended destinations quickly and efficiently. Routing is essential for large networks, such as the Internet, where data packets may need to pass through multiple networks before reaching their final destination.

To facilitate routing, various routing protocols have been developed. These protocols enable routers to communicate with each other and share information about the network topology. In this article, we will discuss the basics of routing and the most common routing protocols.

Basics of Routing

Before diving into routing protocols, it's important to understand the basics of routing. A router is a networking device that connects multiple networks together. A router determines the best path for data packets to travel based on the destination IP address of the packet. To do this, the router uses a routing table, which is a database that contains information about the network topology.

Routing tables are updated dynamically by routing protocols. A routing protocol is a set of rules that routers use to communicate with each other and share information about the network topology. There are two types of routing protocols: interior gateway protocols (IGPs) and exterior gateway protocols (EGPs).

Interior Gateway Protocols (IGPs)

Interior gateway protocols are used within a single autonomous system (AS). An autonomous system is a collection of networks that are under a single administrative domain. There are several IGPs, including:

1. Routing Information Protocol (RIP)
2. Open Shortest Path First (OSPF)
3. Interior Gateway Routing Protocol (IGRP)
4. Enhanced Interior Gateway Routing Protocol (EIGRP)

Routing Information Protocol (RIP)

RIP is a distance-vector routing protocol that uses hop count as its metric. The hop count is the number of routers that a packet must pass through to reach its destination. RIP routers exchange routing information every 30 seconds by sending their entire routing table to their neighbors.

To configure RIP, use the following commands:

scss
Router(config)# router rip
Router(config-router)# network [network-address]

Open Shortest Path First (OSPF)

OSPF is a link-state routing protocol that uses a metric called cost to determine the best path for data packets. The cost is calculated based on the bandwidth of the link. OSPF routers exchange information about their local network topology with other routers in the same area. OSPF routers are divided into three types: internal routers, area border routers, and autonomous system boundary routers.

To configure OSPF, use the following commands:

scss
Router(config)# router ospf [process-id]
Router(config-router)# network [network-address] [wildcard-mask] area [area-id]

Interior Gateway Routing Protocol (IGRP)

IGRP is a distance-vector routing protocol that was developed by Cisco. IGRP uses a composite metric that takes into account bandwidth, delay, reliability, and load. IGRP routers exchange routing information every 90 seconds.

To configure IGRP, use the following commands:

scss
Router(config)# router igrp [process-id]
Router(config-router)# network [network-address]

Enhanced Interior Gateway Routing Protocol (EIGRP)

EIGRP is a hybrid routing protocol that combines aspects of both distance-vector and link-state protocols. EIGRP uses a metric called composite metric, which takes into account bandwidth, delay, reliability, and load. EIGRP routers send partial updates to their neighbors when there is a change in the network topology.

To configure EIGRP, use the following commands:

scss
Router(config)# router eigrp [autonomous-system-number]
Router(config-router)# network [network-address]

Exterior Gateway Protocols (EGPs)

Exterior gateway protocols are used to exchange routing information