Introducing the Long List of Routing Protocols

Over the years, many different routing protocols have been developed. To exchange routing information as in the examples in this chapter, the routers would use a single routing protocol. Each router would use the same routing protocol.

However, you have a choice as to which routing protocol to use. The details of why you would choose one routing protocol over another is beyond the scope of this book. However, to have a conversational knowledge of networking, you should at least know the names of the IP routing protocols and a few basic facts about each. For instance, some routing protocols are defined as public Internet standards in RFCs, whereas others are proprietary from Cisco Systems, which has a significant percentage of the router product market. Also, one routing protocol in particular, Border Gateway Protocol (BGP), is intended for use between Internet service providers (ISPs) and their customers, whereas most others are more appropriate for use inside a single company or organization. A routing protocol that is designed for use inside a company is called an Interior Routing Protocol, and one that is designed for use between different companies is called an Exterior Routing Protocol. Table 12-1 lists the protocols, along with some of these comparison points.

Table 12-1. IP Routing Protocols

Routing Protocol	Public or Proprietary?	Interior or Exterior?
Routing Information Protocol (RIP)	Public	Interior
Interior Gateway Routing Protocol (IGRP)	Proprietary	Interior
Open Shortest Path First (OSPF)	Public	Interior
Enhanced IGRP (EIGRP)	Proprietary	Interior
Border Gateway Protocol (BGP)	Public	Exterior

Most companies choose a single interior routing protocol for use on all the company routers. Of the routing protocols listed, OSPF and EIGRP are the more popular protocols for use inside a single enterprise.