Summing Up
It’s hard to remember that BGP is based on the simple DV algorithm. Instead of one metric (as in the case of RIP or IGRP), the protocol uses multiple attributes to choose the best path.
The environment on which I focused in this chapter -- the use of BGP by ASs such as TraderMary to connect to one or more ISPs -- is even simpler in that only a few attributes are necessary to implement most routing policies. The essentials in this environment are deciding on the optimum routing policy for inbound and outbound traffic given the client’s topology and requirements, and using BGP to implement this policy well, so that failures and load-balancing issues are adequately addressed.
ISPs typically employ BGP in more complex ways, especially with route reflectors and confederations (to solve the problem of I-BGP meshes). This chapter did not focus on these issues.
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