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EIGRP — build the adjacency chain and verify the topology table
Enterprise Intermediate 3 devices 4 checked tasks 100 points Plan lab
Three routers, AS 100, no automatic summarisation. Bring up the neighbours, advertise the loopbacks and links, and confirm each router sees the others’ loopbacks as D routes with a metric you can explain from bandwidth and delay. You build it in a browser, type real commands at each device, and every task below is
checked against the running configuration — so you find out it is wrong before anybody else does.
Open this lab in the simulator
The simulator runs in your browser with nothing to install. This lab is part of the full simulator: open it free for 7 days with a new account, then with a plan. It needs an account, which keeps your progress.
The scenario
Three routers, AS 100, no automatic summarisation. Bring up the neighbours, advertise the loopbacks and links, and confirm each router sees the others’ loopbacks as D routes with a metric you can explain from bandwidth and delay.
Your role: a network engineer on the enterprise team. Level: Intermediate Done when: all 4 goals show as passed (100 points).
Network status
Devices: 3 routers, cabled as drawn. No Layer 1 or Layer 2 faults: every link is connected and up. R1 starts with addresses (G0/1 10.0.12.1/30, L0 1.1.1.1/32). R2 starts with addresses (G0/0 10.0.12.2/30, G0/1 10.0.23.1/30, L0 2.2.2.2/32). R3 starts with addresses (G0/0 10.0.23.2/30, L0 3.3.3.3/32). Known problems
None: nothing is misconfigured. The network is simply not finished: what the goals list is what you have to build or secure. Goals
R2 has two EIGRP neighbours (30 pts) R1 learns R3’s loopback as an EIGRP (D) route (35 pts) R3 learns R1’s loopback (20 pts) Automatic summarisation is off (15 pts) The activity, in order
R2 has two EIGRP neighbours Why: EIGRP shares routes only with neighbours; a mismatched AS number simply never forms one. Verify with: show ip eigrp neighbors R1 learns R3’s loopback as an EIGRP (D) route Why: The code tells you HOW a route was learned, which tells you which process to look at if it is wrong. Verify with: show ip route R3 learns R1’s loopback Why: If the prefix is not in the routing table, the router drops packets for it, whatever else is configured. Verify with: show ip route Automatic summarisation is off Why: This is the task that checks your configuration directly: the line must really be there, not just look right. Verify with: show running-config Tips
Work in the order given: later goals depend on the earlier ones. After every change, run the verify command before moving on; do not guess. Stuck? Read the verify output first. It names the interface, neighbour or route that is wrong. Common mistake: Different AS numbers on neighbours Common mistake: A wildcard mask that does not match the interface Common mistake: Passive interfaces on a transit link Why this matters
EIGRP is an advanced distance-vector protocol: it forms adjacencies, keeps a topology table of alternatives, and computes a metric from bandwidth and delay.
What you will be able to do
Enable EIGRP with the right AS number
Advertise networks and disable auto-summary
Read neighbours, topology and routes
The network
ISR 2911 — 3 devices in all, already cabled.
Gi0/1 10.0.12.1/30 Gi0/0 10.0.12.2/30 Gi0/1 10.0.23.1/30 Gi0/0 10.0.23.2/30 R1 R2 R3 Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
R1 ISR 2911 configure it R2 ISR 2911 configure it R3 ISR 2911 configure it
Cabling
R1 Gi0/1 ↔ R2 Gi0/0 R2 Gi0/1 ↔ R3 Gi0/0
What is configured at the start
These are already configured when the lab opens — including, where this is a troubleshooting lab, the fault itself:
R1 interface g0/1
ip address 10.0.12.1 255.255.255.252
no shutdown
exit
interface lo0
ip address 1.1.1.1 255.255.255.255
no shutdown
exit R2 interface g0/0
ip address 10.0.12.2 255.255.255.252
no shutdown
exit
interface g0/1
ip address 10.0.23.1 255.255.255.252
no shutdown
exit
interface lo0
ip address 2.2.2.2 255.255.255.255
no shutdown
exit R3 interface g0/0
ip address 10.0.23.2 255.255.255.252
no shutdown
exit
interface lo0
ip address 3.3.3.3 255.255.255.255
no shutdown
exit Tasks, and how each one is checked
Every task is decided by reading the live network — a neighbour in FULL, a ping that succeeds, a line in the running configuration — not by looking for a keyword you typed. The same command shows you what the lab sees.
# Task Pts How to verify it yourself
1 R2 has two EIGRP neighbours 30 On R2: show ip eigrp neighbors shows at least 2 neighbour(s). 2 R1 learns R3’s loopback as an EIGRP (D) route 35 On R1: show ip route lists 3.3.3.3/32 with code D. 3 R3 learns R1’s loopback 20 On R3: show ip route lists 1.1.1.1/32. 4 Automatic summarisation is off 15 On R1: show running-config contains the line(s) matching no auto-summary.
Stuck? Ask the coach
Tell the coach what you see or what you tried. It gives you a hint, not the answer, the way a senior engineer would. Included with a free trial or any plan.
Ask the coach
Common mistakes
Different AS numbers on neighbours
A wildcard mask that does not match the interface
Passive interfaces on a transit link
Reference solution
Try it yourself first — the lab checks your work either way. This is one configuration that makes every task pass, device by device:
R1 router eigrp 100
network 10.0.12.0 0.0.0.3
network 1.1.1.1 0.0.0.0
no auto-summary
exit R2 router eigrp 100
network 10.0.12.0 0.0.0.3
network 10.0.23.0 0.0.0.3
network 2.2.2.2 0.0.0.0
no auto-summary
exit R3 router eigrp 100
network 10.0.23.0 0.0.0.3
network 3.3.3.3 0.0.0.0
no auto-summary
exit Where this is examined
CCNA (routing concepts), CCNP ENCOR/ENARSI (EIGRP).
This lab practises these topics in the zNetLaB certification courses:
Related labs
Where to start
The lessons all guided labs plans
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