Description: Configure EIGRP so that routers become neighbors on directly connected interfaces. Confirm that adjacencies form and routes are exchanged.
Why it matters: Understanding how adjacency is formed is the foundation of EIGRP. You’ll learn the core commands and verify successful neighbor relationships.
2. Use EIGRP Named Mode (Modern Configuration)
Description: Configure EIGRP in named mode, which consolidates IPv4 and IPv6 under a single process. Compare it briefly with “classic mode” if you like.
Why it matters: Named mode is the more recent and flexible approach to configuring EIGRP and aligns with current best practices.
3. Verify and Tune EIGRP Timers
Description: Explore Hello and Hold timers. Adjust them to see how EIGRP reacts to faster or slower intervals.
Why it matters: Timing directly affects EIGRP’s convergence speed and stability. It’s a key element in network performance tuning.
4. Summarization (Auto & Manual)
Description: Observe what happens with auto-summary (if supported by your IOS version), then implement manual summarization on specific interfaces.
Why it matters: Summarization limits route advertisement scope, reduces routing table size, and improves convergence—essential in large networks.
5. EIGRP Stub Routing
Description: Configure R4 and/or R5 as stub routers (e.g., eigrp stub connected summary) to see how they respond to and forward queries.
Why it matters: Stub routing prevents queries from flooding to non-transit routers and is widely used in branch/edge scenarios.
6. EIGRP Authentication
Description: Implement MD5 or SHA-based key authentication on selected interfaces. Ensure neighbors still form adjacency with the correct credentials.
Why it matters: Security is crucial in production. EIGRP authentication prevents unauthorized or rogue EIGRP peers from injecting routes.
7. Filtering and Route Control
Description: Use distribute-lists or route-maps to filter or modify routes inbound/outbound.
Why it matters: Real-world networks often require selective route advertisement (e.g., not leaking private subnets). Filtering is a core skill in EIGRP administration.
8. Metric Manipulation and Load Balancing
Offset Lists: Adjust metrics to influence route preference.
Variance: Allow unequal-cost load balancing when multiple paths exist (e.g., R1→R2→R4 vs. R1→R3→R4).
Why it matters: Manipulating EIGRP metrics is key for traffic engineering. Variance demonstrates EIGRP’s unique approach to balancing traffic across different cost paths.
9. EIGRP for IPv6
Description: Assign IPv6 addresses to some interfaces and enable EIGRP IPv6 (typically in named mode). Confirm neighbor formation and IPv6 route exchanges.
Why it matters: IPv6 adoption continues to grow. EIGRP for IPv6 is almost identical to IPv4 but has subtle differences worth exploring.
10. Troubleshooting and Advanced Observability
Description: Practice using show and debug commands (show ip eigrp neighbors, show ip eigrp topology, debug eigrp fsm, etc.). Simulate link failures or misconfigurations and analyze EIGRP’s behavior (e.g., handling SIA, queries).
Why it matters: Real-world issues happen, and understanding how to pinpoint and fix EIGRP problems is essential for any network engineer.