| Routing protocols can be classified in
many ways. One of the ways would take into account where they are
used in relationship to your enterprise. Protocols that run inside an
enterprise are called interior gateway protocols (IGPs). Examples of
IGPs include RIP, IGRP, EIGRP, and OSPF. Protocols that run outside
an enterprise, or between autonomous systems (AS), are called exterior
gateway protocols (EGPs). Typically, EGPs are used to exchange
routing information between ISPs, or in some cases between a
customer's AS and the provider's network. Border Gateway Protocol,
version 4 (BGP4), is the most common EGP and is considered the
Internet standard.
This chapter provides an overview of
the different types of autonomous systems and then focuses on basic
BGP operation, including BGP neighbor negotiation. The chapter then
looks at how to use the Cisco IOS to configure BGP and verify its
operation. Finally, it examines BGP peering and the BGP routing
process.
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