Using an iBGP Mesh

To let the internal routers in the enterprise learn the best BGP routes, one obvious solution is to just run BGP on these routers as well. The not-so-obvious part relates to the implementation choice of what routers need to be iBGP peers with each other. Based on the topology shown in Figure 14-5, at first glance, the temptation might be to run BGP on E1, E2, Core1, and Core2, but use iBGP peers as shown in Figure 14-6.

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Figure 14-6 Partial Mesh of iBGP Peers

The iBGP peers shown in the figure actually match the kinds of IGP neighbor relationships you might expect to see with a similar design. With an IGP routing protocol, ...

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