CloudLabBox
Try the free demo

CCNP Service Provider lab 21 of 23

Troubleshooting: IS-IS and LDP

Work a night-shift ticket: PE1 can't reach PE2. Find four small faults in IS-IS and LDP from the bottom of the stack upwards, fix them, and prove the label path.

Run this lab

It needs Standard: its 4 nodes are set to 4 vCPU and 10,240 MB in total.

In your workspace: Shared, then CCNP Service Provider guided labs, then 21 - Troubleshooting - IS-IS and LDP

Run it on Standard from £5 a day

The free demo can’t run it: it has 6 vCPU and 8 GB, and this lab’s nodes need 4 vCPU and 10,240 MB together. Every lab plan includes every guided lab.

Level
Advanced
Time
About 60 minutes
Nodes need
4 vCPU, 10,240 MB
Smallest plan
Standard

The scenario

It's your first night on call at Fellgate Carrier. A planned change went wrong in the evening, and the engineer who made it has gone home. The NOC has opened one ticket:

Ticket 4471. PE1 can't reach PE2. VPN customers are down. traceroute mpls ipv4 10.255.0.4/32 from PE1 fails.

The intended design is simple:

  • All four routers run IS-IS, Level 2 only, with every loopback advertised.
  • LDP runs on all the core links.
  • PE1 and P1 authenticate their LDP session with the key Lab-Key1.

More than one thing is wrong. Work up from the bottom of the stack, and don't change anything without a reason. There are four faults, and each is a small mistake.

DeviceInterfaceAddressConnects to
PE1Loopback010.255.0.1/32
PE1Gi0/0/0/010.0.12.1/30P1 Gi0/0/0/0
P1Loopback010.255.0.2/32
P1Gi0/0/0/010.0.12.2/30PE1 Gi0/0/0/0
P1Gi0/0/0/110.0.23.1/30P2 Gi0/0/0/0
P2Loopback010.255.0.3/32
P2Gi0/0/0/010.0.23.2/30P1 Gi0/0/0/1
P2Gi0/0/0/110.0.34.1/30PE2 Gi0/0/0/0
PE2Loopback010.255.0.4/32
PE2Gi0/0/0/010.0.34.2/30P2 Gi0/0/0/1

What you’ll practise

  • Work up through IGP, routes, LDP and labels in order
  • Find a level mismatch on an interface
  • Find a loopback missing from the IGP
  • Tell a missing LDP interface from a failed LDP session
  • Prove the fix with traceroute mpls

The tasks

  1. A method
  2. Check the IGP, hop by hop
  3. Find the missing route
  4. Check LDP, hop by hop
  5. Prove the service path

The Lab Tasks pane has the scenario, these tasks, the checks to run, hints and the full solution.

Topology and devices

The network as it opens in EVE-NG, drawn from the lab’s own canvas, and the image each node runs.

Topology of Troubleshooting - IS-IS and LDP4 nodes, 3 links. Every link is listed as text below the diagram.PE1P1P2PE2Gi0/0/0/0Gi0/0/0/0Gi0/0/0/1Gi0/0/0/0Gi0/0/0/1Gi0/0/0/0
4 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • PE1 Gi0/0/0/0 to P1 Gi0/0/0/0
  • P1 Gi0/0/0/1 to P2 Gi0/0/0/0
  • P2 Gi0/0/0/1 to PE2 Gi0/0/0/0
Nodes in Troubleshooting: IS-IS and LDP, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
PE1Cisco IOS XRvxrv-k9-demo-6.3.11 vCPU, 2,560 MB
P1Cisco IOS XRvxrv-k9-demo-6.3.11 vCPU, 2,560 MB
P2Cisco IOS XRvxrv-k9-demo-6.3.11 vCPU, 2,560 MB
PE2Cisco IOS XRvxrv-k9-demo-6.3.11 vCPU, 2,560 MB

How to open this lab

  1. Sign in to your workspace at lab.cloudlabbox.com.

  2. In File Manager, open Shared, then the folder CCNP Service Provider guided labs.

  3. Open 21 - Troubleshooting - IS-IS and LDP and start its nodes, then open Lab Tasks for the scenario and the steps.

The lab is read-only. You can start the nodes and configure the devices, but changes to the topology can’t be saved. To change it, rebuild it in your own folder.

More CCNP Service Provider labs

All CCNP Service Provider labs

Related labs in other courses

CloudLabBox is independent of Cisco. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.