BGP Troubleshooting Capstone: eBGP + iBGP Repair

Bundle lab · $29.99

Advanced CCNP capstone on a compact 3-router, 2-host CML-Free topology. Restore end-to-end reachability to a remote advertised network by diagnosing and correcting two independent BGP issues on the hub router. The design intentionally combines an eBGP edge (R2–R1) with iBGP over loopbacks (R1–R3 with OSPF reachability) so learners validate neighbor formation, next-hop reachability, and route propagation end-to-end.

Learning objectives

• Diagnose why an eBGP session fails to establish using neighbor and summary outputs
• Validate iBGP over loopbacks with OSPF-provided reachability and update-source usage
• Identify and correct next-hop reachability problems that prevent route installation
• Confirm exact-match BGP origination and end-to-end data-plane reachability to an advertised prefix
• Develop a methodical troubleshooting flow: adjacency → reachability → policy/attributes → data-plane test

Troubleshooting focus

• Use show ip bgp summary to confirm BGP neighbor state and timers
• Compare configured remote-as versus the actual neighbor ASN
• Verify iBGP loopback reachability with OSPF and update-source Loopback0 on both ends
• Inspect received routes and next-hop addresses on downstream iBGP peers
• Validate data-plane from the end hosts with ping and traceroute once control-plane is corrected