BGP Lab 5: Local Preference - Preferred Exit

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Configure and validate BGP local-preference to prefer one provider when the same destination prefix is learned from two eBGP neighbors. You will see two equal AS-PATH routes to 172.16.100.0/24 on the edge router and then apply an inbound route-map on the R2 session to set local-preference 200 so the edge prefers exiting via R2. Verification includes host pings/traceroute and router BGP best-path checks.

Learning objectives

• Build and verify eBGP sessions on directly connected /30 links
• Originate an identical service prefix from two providers and observe best-path tie-break
• Set local-preference inbound on a specific neighbor to steer outbound traffic
• Validate BGP best-path selection using show commands and end-host tests
• Differentiate between local-preference (AS-wide) and weight (local-only) in path selection

Troubleshooting focus

• Session not established: verify neighbor IP, remote-as, and L3 reachability over the /30
• Prefix not advertised: confirm exact-match network mask and presence in the RIB
• Policy not taking effect: ensure the route-map is applied inbound on the intended neighbor
• Unexpected best-path: confirm no leftover weight, MED, or as-path prepend influencing selection