The Art of Network Engineering What is BGP?
Sep 10, 2025
In this insightful discussion, Kevin Myers, an expert network engineer with a focus on BGP and WAN design, delves into the intricacies of Border Gateway Protocol. He explains BGP’s evolution from EGP, its role in managing enterprise routing policies, and highlights real-world applications. Kevin also shares strategies for handling overlapping IPv4 addresses during mergers, the effectiveness of BGP communities versus prefix lists, and why iBGP is crucial for scaling internal policies. This engaging conversation sheds light on the complexities and benefits of BGP in modern networking.
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BGP Is A Policy-First Protocol
- BGP is fundamentally a policy protocol designed to connect autonomous systems and implement routing policy across networks.
- It contrasts with IGPs (OSPF/ISIS) which focus on topology and link-level path detail.
Don't Weaponize IGPs For Large-Scale Policy
- Avoid trying to implement heavy policy inside IGPs since they require consistent databases across many routers and outbound filtering is often unsupported.
- Use BGP for scalable filtering at border points so you touch far fewer devices when enforcing policy.
Tag at Origin With Communities
- Tag routes at their origin with BGP communities and filter or act on those tags at border or aggregation points.
- This centralizes policy, reduces config churn, and avoids long, brittle prefix lists scattered across routers.