EIGRP Wildcard Masks: Enabling the Right Interfaces

Bundle lab · $29.99

Build a two-router, two-LAN EIGRP domain and practice precise wildcard-masked network statements so only the intended interfaces participate. R1 has an extra LAN on Ethernet0/2 (172.16.99.0/24) that must be excluded from EIGRP. Validate with show commands and end-host pings that the correct LANs are exchanged and the excluded LAN is not advertised.

Learning objectives

• Enable classic EIGRP with a consistent AS (200) and classless operation (no auto-summary).
• Use precise wildcard-masked network statements to include specific interfaces and exclude others.
• Verify participating EIGRP interfaces and advertised networks with show ip eigrp interfaces and show ip protocols.
• Confirm that only intended routes appear in neighbors' routing tables (show ip route eigrp) and with host pings.

Troubleshooting focus

• If no neighbor forms on the transit, confirm both routers use the same EIGRP AS (200) and the correct wildcard covers 10.0.23.0/30.
• If an unintended interface shows in show ip eigrp interfaces, tighten or remove an overly-broad network statement.
• If a LAN route is missing on the neighbor, ensure the correct LAN network statement is present and that no ACLs block EIGRP (not used here).
• If host pings fail but EIGRP looks good, check host IP/gateway and router LAN interfaces for correct addressing and link state.