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JNCIA-Junos lab 14 of 15

Troubleshooting interfaces and static routes

A contractor rebuilt the three-site static network overnight and left it broken in six places. Work from five user complaints to the faults, layer by layer, using only show commands and ping, and fix each one without breaking anything else.

Run this lab

It needs Standard: its 3 nodes are set to 12 vCPU and 15,360 MB in total.

In your workspace: Shared, then JNCIA-Junos JN0-106 guided labs, then 14 - Troubleshooting interfaces and static routes

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 12 vCPU and 15,360 MB together. Every lab plan includes every guided lab.

Level
Intermediate
Time
About 60 minutes
Nodes need
12 vCPU, 15,360 MB
Smallest plan
Standard

The scenario

A contractor rebuilt the three-site network overnight from the design below. This morning the help desk has five complaints. The contractor has gone home. The network contains six faults; nothing else is wrong, so you should not need to add anything that is not in the design.

The design

RouterInterfaceShould be
HQge-0/0/0 (fibre to DEPOT)172.16.14.1/30, 2001:db8:14::1/64
HQge-0/0/1 unit 100 (carrier VLAN 100 to WH)172.16.12.1/30, 2001:db8:12::1/64
WHge-0/0/0 unit 100 (carrier VLAN 100 to HQ)172.16.12.2/30, 2001:db8:12::2/64
WHge-0/0/1 (fibre to DEPOT)172.16.24.1/30
DEPOTge-0/0/0 (fibre to HQ)172.16.14.2/30, 2001:db8:14::2/64
DEPOTge-0/0/1 (fibre to WH)172.16.24.2/30
LANs (ge-0/0/2)HQ 10.1.0.1/24 · WH 10.2.0.1/24 · DEPOT 10.4.0.1/24 and 10.4.1.1/24IPv6 2001:db8:1::1, 2:: and 4:: /64
RouterStatic routes in the design
HQ10.4.0.0/22 via 172.16.14.2 (backup via 172.16.12.2, preference 7); 10.2.0.0/24 via 172.16.12.2; IPv6 2001:db8:4::/64 via 2001:db8:14::2 and 2001:db8:2::/64 via 2001:db8:12::2
WHdefault via 172.16.12.1; 10.4.0.0/22 via 172.16.24.2 (straight to the depot); IPv6 default via 2001:db8:12::1
DEPOTdefault via 172.16.14.1 (backup via 172.16.24.1, preference 7); IPv6 default via 2001:db8:14::1

The complaints

  1. "Nobody at HQ can reach the depot."
  2. "HQ cannot reach the warehouse, yet both routers say their interfaces are up."
  3. "The monitoring system shows the WH-DEPOT fibre as down."
  4. "IPv6 from HQ to the depot LAN times out." (Look at this one after complaint 1 is fixed.)
  5. "Traffic from the warehouse to the depot's second subnet, 10.4.1.0/24, goes the long way round through HQ."

What you’ll practise

  • Troubleshoot bottom-up: physical and admin state, Layer 2, addressing, then routing
  • Find wrong addresses, disabled ports and VLAN ID mismatches from show output
  • Find hidden, inactive and wrong static routes, and next hops that do not resolve
  • Prove the path with traceroute, and IPv6 reachability with the neighbour table

The tasks

  1. Work bottom-up
  2. Complaint 1: HQ cannot reach the depot
  3. Complaint 2: the carrier link
  4. Complaint 3: the WH-DEPOT fibre
  5. Complaint 4: IPv6 to the depot
  6. Complaint 5: the long way round
  7. Prove it

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 interfaces and static routes3 nodes and 3 networks, 6 links. Every link is listed as text below the diagram.HQWHDEPOTHQ-LANWH-LANDEPOT-LANge-0/0/2ge-0/0/2ge-0/0/2ge-0/0/0ge-0/0/0ge-0/0/1ge-0/0/0ge-0/0/1ge-0/0/1
3 nodes and 3 networks, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • HQ ge-0/0/0 to DEPOT ge-0/0/0
  • HQ ge-0/0/1 to WH ge-0/0/0
  • WH ge-0/0/1 to DEPOT ge-0/0/1
  • HQ ge-0/0/2 to HQ-LAN (network)
  • WH ge-0/0/2 to WH-LAN (network)
  • DEPOT ge-0/0/2 to DEPOT-LAN (network)
Nodes in Troubleshooting interfaces and static routes, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
HQJuniper vJunos-routervjunosrouter-24.2R1-S2.54 vCPU, 5,120 MB
WHJuniper vJunos-routervjunosrouter-24.2R1-S2.54 vCPU, 5,120 MB
DEPOTJuniper vJunos-routervjunosrouter-24.2R1-S2.54 vCPU, 5,120 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 JNCIA-Junos JN0-106 guided labs.

  3. Open 14 - Troubleshooting interfaces and static routes 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.

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