zNetLaB › Guided labs › Service Provider
IS-IS — two areas, Level 1 and Level 2
Service Provider Advanced 3 devices 5 checked tasks 100 points Plan lab
R1 is a Level 1 router in area 49.0001, R2 joins that area to the backbone as L1/L2, and R3 is Level 2 only in area 49.0002. Bring IS-IS up and watch the attached bit give R1 a default route while area 49.0001’s prefixes are leaked into Level 2. 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
R1 is a Level 1 router in area 49.0001, R2 joins that area to the backbone as L1/L2, and R3 is Level 2 only in area 49.0002. Bring IS-IS up and watch the attached bit give R1 a default route while area 49.0001’s prefixes are leaked into Level 2.
Your role: an engineer in the provider’s network operations centre. Level: Advanced Done when: all 5 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-L1 starts with addresses (G0/0 10.0.12.1/24, L0 1.1.1.1/32). R2-L1L2 starts with addresses (G0/0 10.0.12.2/24, G0/1 10.0.23.2/24). R3-L2 starts with addresses (G0/0 10.0.23.3/24, L0 3.3.3.3/32). Known problems
The network worked and now does not: the scenario above says what users report. The cause is a configuration fault, not a cable. Find it with show commands (interfaces, routes, neighbours, running-config) before you change anything; fix only what is wrong. Goals
R1 has a Level 1 adjacency (20 pts) R3 has a Level 2 adjacency (20 pts) R1 gets a Level 1 default from the attached router (25 pts) R3 learns R1’s loopback leaked into Level 2 (20 pts) R1 reaches R3’s loopback (15 pts) The activity, in order
R1 has a Level 1 adjacency Why: Each goal is a state the lab can check on the running device. Verify with: show running-config R3 has a Level 2 adjacency Why: Each goal is a state the lab can check on the running device. Verify with: show running-config R1 gets a Level 1 default from the attached router 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 leaked into Level 2 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 R1 reaches R3’s loopback Why: A ping needs a route in BOTH directions. This is the end-to-end proof that everything before it worked. Verify with: ping 3.3.3.3 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. Why this matters
R1 is a Level 1 router in area 49.0001, R2 joins that area to the backbone as L1/L2, and R3 is Level 2 only in area 49.0002. Bring IS-IS up and watch the attached bit give R1 a default route while area 49.0001’s prefixes are leaked into Level 2.
What you will be able to do
R1 has a Level 1 adjacency
R3 has a Level 2 adjacency
R1 gets a Level 1 default from the attached router
R3 learns R1’s loopback leaked into Level 2
The network
ISR 2911 — 3 devices in all, already cabled.
Gi0/0 10.0.12.1/24 Gi0/0 10.0.12.2/24 Gi0/1 10.0.23.2/24 Gi0/0 10.0.23.3/24 R1-L1 R2-L1L2 R3-L2 Drawn from this lab: devices, cables, ports and the addresses already set. Device Model Address already set
R1-L1 ISR 2911 configure it R2-L1L2 ISR 2911 configure it R3-L2 ISR 2911 configure it
Cabling
R1-L1 Gi0/0 ↔ R2-L1L2 Gi0/0 R2-L1L2 Gi0/1 ↔ R3-L2 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-L1 interface g0/0
ip address 10.0.12.1 255.255.255.0
no shutdown
exit
interface lo0
ip address 1.1.1.1 255.255.255.255
no shutdown
exit R2-L1L2 interface g0/0
ip address 10.0.12.2 255.255.255.0
no shutdown
exit
interface g0/1
ip address 10.0.23.2 255.255.255.0
no shutdown
exit R3-L2 interface g0/0
ip address 10.0.23.3 255.255.255.0
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 R1 has a Level 1 adjacency 20 Checked automatically against the device’s live state (isisLevel). 2 R3 has a Level 2 adjacency 20 Checked automatically against the device’s live state (isisLevel). 3 R1 gets a Level 1 default from the attached router 25 On R1-L1: show ip route lists 0.0.0.0/0 with code i L1. 4 R3 learns R1’s loopback leaked into Level 2 20 On R3-L2: show ip route lists 1.1.1.1/32 with code i L2. 5 R1 reaches R3’s loopback 15 On R1-L1: ping 3.3.3.3 must succeed.
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
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-L1 router isis
net 49.0001.0000.0000.0001.00
is-type level-1
exit
interface g0/0
ip router isis
exit
interface lo0
ip router isis
exit R2-L1L2 router isis
net 49.0001.0000.0000.0002.00
exit
interface g0/0
ip router isis
exit
interface g0/1
ip router isis
exit R3-L2 router isis
net 49.0002.0000.0000.0003.00
is-type level-2-only
exit
interface g0/0
ip router isis
exit
interface lo0
ip router isis
exit Where this is examined
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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