External Routing—BGP

The Border Gateway Protocol (BGP) was developed to provide a way to exchange network reachability information between ASs. The main reason BGP is used today to pass network information between autonomous systems is because it enables Network Operators to implement a routing policy.

Figure 6.5. Implementing a simple BGP policy.

Who Determines Policies?

People define routing policies. You make certain choices about how you would like to route traffic between your network and other networks that you interconnect with. BGP enables you to program your routers to select paths to other networks based upon criteria that you ...

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