🧪 Part 4 of 5 · Lab Guide

EIGRP Module A · Enterprise Routing Master Series

Hands-On Lab: EIGRP Fundamentals, RTP & Adjacency

Four progressive lab tasks with production-grade topology, step-by-step CLI solutions, and verification checkpoints. Import the included .unl file into EVE-NG and complete the tasks to master EIGRP neighbor formation, static vs dynamic peering, timer tuning, and failure simulation.

👤 Author: Hrishi Pradhan

🎯 Level: Basic to Advanced

🧪 Tasks: 4 Progressive Labs

⚙️ Topology: EVE-NG .unl Ready

📐 Lab Topology (3-Pillar Standard)

Visual diagram, device inventory table, and traffic legend

Topology

📌 How to Read This Topology

The topology is documented using the Pause4Tech 3-Pillar Standard: (1) Topology diagram for visual reference, (2) device inventory table for addressing, and (3) traffic legend explaining protocol flows.

🔷 Pillar 1 — Topology Diagram

EIGRP Module A Lab Topology — AS 1234 with Core-R1, Dist-R2, Dist-R3, Host-A, Host-B, ISP_Router

Figure 1 — EIGRP Module A Lab Topology (AS 1234) with EIGRP Hello, Update/Query/Reply flows and summarization boundaries.

📐 Show ASCII Fallback (for terminal users)

+-------------------+ | ISP_Router | | (Simulated WAN) | +--------+----------+ | Gi0/0 (10.0.0.0/30) | +--------+----------+ | Core-R1 (AS 1234)| | RID: 1.1.1.1 | +----+--------+-----+ | | Gi0/1 (10.1.12.0/24)| | Gi0/2 (10.1.13.0/24) | | +--------+--+ +--+--------+ | Dist-R2 | | Dist-R3 | | RID: 2.2.2.2| | RID: 3.3.3.3| +----+-------+ +----+------+ | | (VLAN 10) (VLAN 20) 10.1.10.0/24 10.1.20.0/24 | | +----+----+ +------+-----+ | Host-A | | Host-B | | .10 | | .10 | +---------+ +------------+

🔷 Pillar 2 — Device Inventory Table

Device	Role	Interfaces	IP Addresses	EIGRP AS	Router ID
Core-R1	Hub / Border	Gi0/0 (to ISP) Gi0/1 (to R2) Gi0/2 (to R3) Lo0	10.0.0.1/30 10.1.12.1/24 10.1.13.1/24 1.1.1.1/32	1234	1.1.1.1
Dist-R2	Distribution	Gi0/0 (to R1) Gi0/1 (to Host-A) Lo0	10.1.12.2/24 10.1.10.1/24 2.2.2.2/32	1234	2.2.2.2
Dist-R3	Distribution	Gi0/0 (to R1) Gi0/1 (to Host-B) Lo0	10.1.13.2/24 10.1.20.1/24 3.3.3.3/32	1234	3.3.3.3
Host-A	End device	Eth0	10.1.10.10/24 (GW .1)	N/A	N/A
Host-B	End device	Eth0	10.1.20.10/24 (GW .1)	N/A	N/A
ISP_Router	Simulated WAN	Gi0/0	10.0.0.2/30	65001	9.9.9.9

🔷 Pillar 3 — Traffic Flow & Protocol Legend

Symbol	Meaning
🟢 Green Arrows	EIGRP Hello packets (multicast 224.0.0.10)
🔵 Blue Arrows	EIGRP Update / Query / Reply messages
🟠 Orange Dashed	Summarization route boundaries
⚫ Black Lines	Physical Ethernet links
🟣 Purple Dashed	Static unicast neighborship (when applicable)

🧪 Lab Tasks (4 Progressive Scenarios)

Step-by-step configuration with verification checkpoints

Hands-On

Basic EIGRP Configuration & Neighbor Verification

⏱ ~15 min

Objective: Enable EIGRP AS 1234 on all routers, form adjacencies, and verify routes for loopbacks and connected subnets appear in the routing table.

Why This Matters in Production: Correct neighbor formation is the foundation of any dynamic routing deployment. Misconfigured AS numbers, passive interfaces, or missing network statements cause complete loss of routing.

📝 Solution — Core-R1

router eigrp 1234
 network 10.0.0.0 0.255.255.255
 network 10.1.12.0 0.0.0.255
 network 10.1.13.0 0.0.0.255
 network 1.1.1.1 0.0.0.0
 no auto-summary

📝 Solution — Dist-R2

router eigrp 1234
 network 10.1.12.0 0.0.0.255
 network 10.1.10.0 0.0.0.255
 network 2.2.2.2 0.0.0.0
 no auto-summary

📝 Solution — Dist-R3

router eigrp 1234
 network 10.1.13.0 0.0.0.255
 network 10.1.20.0 0.0.0.255
 network 3.3.3.3 0.0.0.0
 no auto-summary

✅ Verification

Core-R1# show ip eigrp neighbors
H   Address         Interface  Hold  Uptime   SRTT   RTO  Q  Seq
0   10.1.12.2       Gi0/1       13    00:10:23  12     200   0  45
1   10.1.13.2       Gi0/2       11    00:09:15  8      200   0  32

Core-R1# show ip route eigrp
D    2.2.2.2/32     [90/158720] via 10.1.12.2, 00:10:23, Gi0/1
D    3.3.3.3/32     [90/158720] via 10.1.13.2, 00:09:15, Gi0/2
D    10.1.10.0/24  [90/158720] via 10.1.12.2, 00:10:23, Gi0/1
D    10.1.20.0/24  [90/158720] via 10.1.13.2, 00:09:15, Gi0/2

Static vs Dynamic Neighborship Configuration

⏱ ~20 min

Objective: Configure static unicast neighborship between Core-R1 and Dist-R2, while maintaining dynamic multicast neighborship with Dist-R3. Verify both adjacency types coexist correctly.

Why This Matters in Production: Static unicast neighborship is used in security-conscious environments or when multicast traffic is restricted. Understanding how to deploy it without breaking dynamic adjacencies is a common enterprise requirement.

📝 Solution — Core-R1 (Static for R2, Dynamic for R3)

router eigrp 1234
 neighbor 10.1.12.2 GigabitEthernet0/1

📝 Solution — Dist-R2 (Static for R1)

router eigrp 1234
 neighbor 10.1.12.1 GigabitEthernet0/0

📝 Solution — Dist-R3 (No Change — Dynamic)

! No additional configuration required.
! Dist-R3 continues to use multicast 224.0.0.10 for discovery.

✅ Verification

Core-R1# show ip eigrp neighbors
H   Address         Interface  Hold  Uptime   SRTT   RTO  Q  Seq
0   10.1.12.2       Gi0/1       12    00:05:23  10     200   0  12   ← Static (unicast)
1   10.1.13.2       Gi0/2       14    00:05:15  8      200   0  10   ← Dynamic (multicast)

! Confirm traffic counters increase differently per neighbor type
Core-R1# show ip eigrp traffic

RTP Timer Tuning & Failure Simulation

⏱ ~25 min

Objective: Modify EIGRP hello and hold timers on one interface, observe neighbor behavior when timers mismatch, then correct the mismatch to re-establish adjacency.

Why This Matters in Production: Timers can be tuned to accelerate convergence on high-speed links or accommodate congested WAN environments. Understanding the mismatch symptoms is critical for on-call troubleshooting.

📝 Step 1 — Modify Timers on Core-R1 Gi0/1

interface GigabitEthernet0/1
 ip hello-interval eigrp 1234 3
 ip hold-time eigrp 1234 9

📝 Step 2 — Observe Debug on Dist-R2 (Keep Default 5/15)

Dist-R2# debug eigrp packets hello
! Wait 30 seconds — you will see asymmetric timing

! Sample output shows Core-R1 sending Hellos every 3s while
! Dist-R2's default hold timer of 15s may cause early expiry.

📝 Step 3 — Align Timers on Dist-R2

interface GigabitEthernet0/0
 ip hello-interval eigrp 1234 3
 ip hold-time eigrp 1234 9

📝 Step 4 — Restore Default Timers (Cleanup)

! On both Core-R1 Gi0/1 and Dist-R2 Gi0/0
interface GigabitEthernet0/1
 no ip hello-interval eigrp 1234
 no ip hold-time eigrp 1234

✅ Verification

Core-R1# show ip eigrp neighbors
H   Address         Interface  Hold  Uptime   SRTT   RTO  Q  Seq
0   10.1.12.2       Gi0/1       12    00:00:35  10     200   0  6

Core-R1# show ip eigrp interfaces detail GigabitEthernet0/1
  Hello-interval is 5, Hold-time is 15

Neighbor Failure Simulation & Recovery

⏱ ~20 min

Objective: Simulate a neighbor failure by shutting down an interface, observe the neighbor flap and route removal, then restore the interface and verify full convergence.

Why This Matters in Production: Understanding how EIGRP reacts to interface failures is essential for predicting failover behavior and validating network resilience. This lab simulates the exact symptoms you'll see in production during a link failure.

📝 Step 1 — Baseline: Verify Current State

Core-R1# show ip eigrp neighbors
! Record the current neighbor count and route entries

Core-R1# show ip route eigrp
! Note the routes learned via Dist-R2

📝 Step 2 — Simulate Failure: Shut Down Gi0/1 on Core-R1

Core-R1# configure terminal
Core-R1(config)# interface GigabitEthernet0/1
Core-R1(config-if)# shutdown

📝 Step 3 — Observe Neighbor Loss & Route Removal

! Watch syslog messages appear:
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1234: Neighbor 10.1.12.2 
  (GigabitEthernet0/1) is down: interface down

Core-R1# show ip eigrp neighbors
! Dist-R2 (10.1.12.2) should no longer appear

Core-R1# show ip route eigrp
Core-R1# show ip route eigrp
! Routes via Dist-R2 should be removed from the table

Core-R1# show ip eigrp topology | include 10.1.10.0
! Route should be in Active state OR removed entirely

📝 Step 4 — Restore the Interface

Core-R1# configure terminal
Core-R1(config)# interface GigabitEthernet0/1
Core-R1(config-if)# no shutdown

📝 Step 5 — Verify Full Recovery

! Watch syslog for neighbor coming back:
%DUAL-5-NBRCHANGE: EIGRP-IPv4 1234: Neighbor 10.1.12.2 
  (GigabitEthernet0/1) is up: new adjacency

✅ Verification

Core-R1# show ip eigrp neighbors
H   Address         Interface  Hold  Uptime   SRTT   RTO  Q  Seq
0   10.1.12.2       Gi0/1       12    00:00:15  10     200   0  3   ← Restored
1   10.1.13.2       Gi0/2       14    00:15:32  8      200   0  88

Core-R1# show ip route eigrp
D    2.2.2.2/32     [90/158720] via 10.1.12.2, 00:00:15, Gi0/1  ← Restored
D    10.1.10.0/24  [90/158720] via 10.1.12.2, 00:00:15, Gi0/1  ← Restored

💡 Production Insight

Notice how EIGRP immediately queried neighbors when the interface went down. If a Feasible Successor existed, failover would be instant. Since only Core-R1 had a path, the route entered Active state and was removed. This is why Feasible Successors matter — they enable instant failover without query propagation.

Challenge Scenario — Multi-Issue Troubleshooting

⏱ ~30 min · Expert

Objective: A real-world scenario where multiple EIGRP issues are introduced simultaneously. Your job is to identify and fix ALL of them without being told what's wrong.

Why This Matters in Production: Real networks rarely have single, isolated problems. This challenge tests your ability to diagnose multiple interacting issues — exactly what senior engineers face during production outages.

📝 Scenario Setup

A junior engineer made "small tweaks" to fix a performance issue. Now EIGRP adjacency is flapping between Core-R1 and Dist-R2, and routes are incomplete. Your job: identify every misconfiguration and restore full operation.

📝 Intentional Misconfigurations (Do NOT look ahead if you want the challenge)

🔒 Click to reveal the misconfigurations (only after attempting yourself)

Mismatched hello timers — Core-R1 Gi0/1 set to 3s hello / 9s hold, Dist-R2 still at default 5s / 15s
K-value mismatch — Dist-R2 changed to metric weights 0 1 1 1 1 1
Duplicate router ID — Dist-R2 set its RID to 1.1.1.1 (same as Core-R1)
Wrong AS number — Dist-R3 changed its EIGRP AS to 4321

📝 Diagnostic Commands

Core-R1# show ip eigrp neighbors
Core-R1# show ip eigrp interfaces detail GigabitEthernet0/1
Core-R1# show ip protocols | include K-values|Router ID|AS
Core-R1# show log | include EIGRP|DUAL
Core-R1# debug eigrp packets

✅ Expected Fixes

! Fix 1: Align timers on both sides
Core-R1(config)# interface GigabitEthernet0/1
Core-R1(config-if)# ip hello-interval eigrp 1234 5
Core-R1(config-if)# ip hold-time eigrp 1234 15

! Fix 2 & 3: Restore default K-values and unique RID on Dist-R2
Dist-R2(config)# router eigrp 1234
Dist-R2(config-router)# metric weights 0 1 0 1 0 0
Dist-R2(config-router)# eigrp router-id 2.2.2.2

! Fix 4: Restore correct AS on Dist-R3
Dist-R3(config)# no router eigrp 4321
Dist-R3(config)# router eigrp 1234
Dist-R3(config-router)# network 10.1.13.0 0.0.0.255
Dist-R3(config-router)# network 10.1.20.0 0.0.0.255
Dist-R3(config-router)# network 3.3.3.3 0.0.0.0
Dist-R3(config-router)# no auto-summary

! Final verification
Core-R1# show ip eigrp neighbors
! All neighbors should show FULL state
Core-R1# show ip route eigrp
! All expected routes should be present

💡 The Real-World Lesson

This challenge simulates a real production event: multiple interacting faults that cascade. Senior engineers don't just fix one problem — they trace the pattern across the network. Note how each misconfiguration produced different syslog messages, giving you clues to work with.

📦 Download Lab Packages (.unl Files)

Five progressive .unl topologies — from basic to expert challenge

Downloads

📌 How to Use These Files

Each lab has its own .unl file with the exact topology and starting configuration. Download the file for the lab you're working on, import it into EVE-NG, and follow the lab tasks. New to lab setup? Read the Lab Setup Master Guide first.

1 Basic Lab

EIGRP_A_Lab1_Basic.unl

⭐ Basic · ~15 min

2 Static Neighbor

EIGRP_A_Lab2_StaticNeighbor.unl

⭐⭐ Basic+ · ~20 min

3 Timers & RTP

EIGRP_A_Lab3_Timers.unl

⭐⭐⭐ Intermediate · ~25 min

4 Failure Recovery

EIGRP_A_Lab4_Scenario.unl

⭐⭐⭐⭐ Advanced · ~20 min

5 Expert Challenge

EIGRP_A_Lab5_Challenge.unl

⭐⭐⭐⭐⭐ Expert · ~30 min

⏳ Downloads Coming Soon

The .unl files are being prepared for hosting on Cloudflare R2. Download links will be activated shortly. In the meantime, you can manually build the topology using the device inventory table above.