BGP Peering & Path Selection
BGP path selection is one of the hardest things to internalize from reading alone. This lab gives you a real eBGP/iBGP topology to break and fix until best-path selection actually clicks.
Not a mockup, this is the real topology
The problem
Two eBGP paths exist to the same prefix, one with a visibly shorter AS-path, but the router keeps selecting the longer one as best. Nothing about the configuration looks obviously wrong at first glance.
What you'll practice
- Establish eBGP and iBGP peering sessions between routers
- Walk the BGP best-path algorithm step by step on real routes
- Influence path selection with local-preference and AS-path prepending
- Tag and filter routes using BGP communities
- Diagnose a stuck or flapping BGP session
The topology
Four routers form two autonomous systems connected by dual eBGP links, with an iBGP session inside each AS, enough redundancy to force real best-path decisions instead of one obvious route.
Topology diagram
Frequently asked
Do I need to build the BGP peering topology myself?
No. The peering topology, IOS images and base configs are pre-built. You configure policy, not infrastructure.
Is this suitable for CCNP or just CCIE-level BGP?
It's scoped to CCNP ENARSI BGP topics (peering, best-path, policy), advanced enough to also warm up for CCIE-level BGP practice.
Ready to run this lab yourself?
No setup, no image sourcing. Book a session or ask for a live demo.