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Network+ lab 24 of 27

Troubleshooting 1: switching faults

Four help-desk tickets, four real faults in a two-switch office: a port in the wrong VLAN, an uplink shut by BPDU guard, a VLAN missing from a trunk and a port left administratively down. You work each one through the CompTIA troubleshooting method, from symptoms to documented fix.

Run this lab

It needs Lite: its 6 nodes are set to 6 vCPU and 5,120 MB in total. That fits the free demo too.

In your workspace: Shared, then CompTIA Network Plus N10-009 guided labs, then 24 - Troubleshooting 1 - switching faults

Try it free for 30 minutesRun it on Lite from £3 a day

The free demo needs no card and no email. Every lab plan includes every guided lab.

Level
Intermediate
Time
About 60 minutes
Nodes need
6 vCPU, 5,120 MB
Smallest plan
Lite

The scenario

Monday morning at Harbour Logistics. Over the weekend a contractor "tidied up" the switches, and four tickets are waiting. The design is simple: R1 routes for Sales (VLAN 10) and Accounts (VLAN 20) with router-on-a-stick, SW1 and SW2 are joined by a trunk that should carry both VLANs, and everyone uses the file server at 10.10.99.10.

HostSwitch portVLANAddressGateway
PC1 (Sales)SW1 Gi0/21010.10.10.11/2410.10.10.1
PC2 (Accounts)SW2 Gi0/12010.10.20.12/2410.10.20.1
PC3 (Sales)SW2 Gi0/21010.10.10.13/2410.10.10.1
TicketReported bySymptom
#101PC1"I can't reach the file server or even ping my gateway."
#102everyone on SW2"Nothing works on our side of the building since this morning."
#103PC2"Still can't reach anything after #102 was fixed."
#104PC3"The link light on my desk port is off."

The PCs' own settings are correct: the faults are all in the network.

What you’ll practise

  • Apply the seven-step troubleshooting methodology to real tickets
  • Read interface status: up, administratively down, err-disabled
  • Find an incorrect VLAN assignment from the switch, not the PC
  • Recover an err-disabled port after removing its cause
  • Trace a VLAN across trunks and fix an allowed-VLAN list
  • Document the root cause, fix and prevention for each ticket

The tasks

  1. Ticket #101, PC1 can't reach its gateway
  2. Ticket #102, the whole of SW2 is offline
  3. Ticket #103, Accounts on SW2 still can't connect
  4. Ticket #104, PC3's link light is off
  5. Verify everything and document

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 1 - switching faults6 nodes, 5 links. Every link is listed as text below the diagram.R1SW1SW2PC1PC2PC3Gi0/1eth0Gi0/2eth0Gi0/2eth0Gi0/0Gi0/0Gi0/1Gi0/0
6 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • R1 Gi0/0 to SW1 Gi0/0
  • SW1 Gi0/1 to SW2 Gi0/0
  • SW1 Gi0/2 to PC1 eth0
  • SW2 Gi0/1 to PC2 eth0
  • SW2 Gi0/2 to PC3 eth0
Nodes in Troubleshooting 1: switching faults, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
R1Cisco IOSvvios-adventerprisek9-m.SPA.159-3.M61 vCPU, 512 MB
SW1Cisco IOSvL2viosl2-adventerprisek9-m.ssa.high_iron_202009291 vCPU, 768 MB
SW2Cisco IOSvL2viosl2-adventerprisek9-m.ssa.high_iron_202009291 vCPU, 768 MB
PC1VPCS hostBuilt in to EVE-NGCounted as 1 vCPU, 1,024 MB
PC2VPCS hostBuilt in to EVE-NGCounted as 1 vCPU, 1,024 MB
PC3VPCS hostBuilt in to EVE-NGCounted as 1 vCPU, 1,024 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 CompTIA Network Plus N10-009 guided labs.

  3. Open 24 - Troubleshooting 1 - switching faults 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 CompTIA, Cisco and Netgate. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.