Case Study: BGP

I have talked a lot about the reliance of BGP to the underlying IGP routing and presence of the routes to ensure effective and proper routing is taking place. This case study is courtesy of I-NAP Ltd. (, an ISP in the United Kingdom who provides a full range of connectivity services. I helped them resolve this issue, and they have graciously allowed the situation and resulting solution to be included here.

I-NAP and I hope that this case study demonstrates the use of BGP and its operational requirements to help you better understand the concepts presented in this chapter.

Problem Description

When executing a traceroute, the path taken is through the level 3 Internet link; this is suboptimal, as shown in the

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