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BGP's main strength is its capability to
impose routing policy, primarily through route maps that manipulate
BGP path attributes. These attributes allow for very precise and
complex policy implementation. However, as ISP's scale their BGP
routing to include dozens, and even hundreds of routers, BGP's
precision can become an administrative nightmare.
The Cisco IOS offers several methods to
make scaling BGP easier on administrators and on the BGP routers
themselves. This chapter discusses the following key features needed
to simplify and streamline large BGP domains: route reflectors, route
filtering, the Community attribute, and peer groups. Moreover, we will
examine BGP scalability issues such as redundancy, load balancing,
multihomed connections, and route redistribution.
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