What is the difference between Interior gateway protocol and Exterior gateway protocol?

Answer 1

Interior vs. Exterior Routing ProtocolRouting is the process of moving data from one network to another. Routing is unnecessary unless you have multiple networks on different address ranges different combinations of IP addresses and subnet masks, for example). If you don't, you need to look at bridging or switching. You don't need to run a routing protocol unless you have multiple networks served by more than one router (and even then, manual static routes are easier for small networks). Once you get beyond three routers, it's time to start thinking about dynamic routing protocols. If you are connecting your networks to the internet, you will also need to think about running more than one kind of routing protocol.

INTERIOR GATEWAY PROTOCOLS

Interior Gateway Protocols (IGPs) handle routing within an Autonomous System (one routing domain). In plain English, IGP's figure out how to get from place to place between the routers you own. These dynamic routing protocols keep track of paths used to move data from one end system to another inside a network or set ofnetworks that you administrate (all of the networks you manage combined are usually just one Autonomous System). IGP's are how you get all the networks communicating with each other.

IGP's fall into two categories:

Distance Vector Protocols

Routing Information Protocol (RIP)

Interior Gateway Routing Protocol (IGRP)

Link State Protocols

Open Shortest Path First (OSPF)

Intermediate System to Intermediate System (IS-IS)

EXTERIOR GATEWAY PROTOCOLS

To get from place to place outside your network(s), i.e. on the Internet, you must use an Exterior Gateway Protocol. Exterior Gateway Protocols handle routing outside an Autonomous System and get you from your network, through your Internet provider'snetwork and onto any other network. BGP is used by companies with more than one Internet provider to allow them to have redundancy and load balancing of their data transported to and from the Internet.

Examples of an EGP:

Border Gateway Protocol (BGP)

Exterior Gateway Protocol (Replaced by BGP)