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T
his chapter covers BGP, which stands for Border Gateway
Protocol. BGP will be discussed in great detail, not only in this chapter but
in the two following this one as well. Here we'll focus on BGP terminology
and its basics components. Chapter 8, "Configuring Basic BGP," will focus
on how BGP works and configuring BGP. Chapter 9, "Monitoring, Trou-
bleshooting, and Scaling BGP," will focus on the more advanced uses of
BGP, including scaling, policy implementation, and optimization techniques.
For some time now, Cisco has required an understanding of BGP as a
requirement for obtaining your CCIE. But in order to fulfill the CCNP
requirements, you needed only a basic overview and never had to deal with
BGP configurations or advanced configurations. There is no way that we can
project to you the actual complexities of configuring BGP for an ISP needing
20 or more paths going through ISPs. This is not an uncommon scenario,
and we will prepare you to configure and support BGP in a real Internet
environment.
BGP is one of the most complex routing protocols I have ever seen. It is
used to connect multiple autonomous systems, which we'll discuss in detail.
In this chapter, we'll focus on the following:
Autonomous systems, including stud autonomous systems and transit
autonomous systems
BGP peers
Internal BGP
External BGP
Routing protocols
When to use and when not to use BGP
Ingress filtering
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