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CCNA lab 9 of 46

802.1Q trunks: native VLAN and DTP

Three switches in a row, one link that never became a trunk and another that negotiated itself into a native VLAN mismatch. Replace guesswork with static 802.1Q trunks, an unused native VLAN and a pruned allowed list.

Run this lab

It needs Lite: its 6 nodes are set to 6 vCPU and 6,144 MB in total. That fits the free demo too.

In your workspace: Shared, then CCNA 200-301 guided labs, then 09 - 802-1Q trunks - native VLAN and DTP

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Level
Intermediate
Time
About 50 minutes
Nodes need
6 vCPU, 6,144 MB
Smallest plan
Lite

The scenario

Millbrook Engineering has three switches in a row along a corridor. The VLANs and the PC ports were set up last week, but the inter-switch links were left to "sort themselves out". Sales (VLAN 10) on S1 can't reach their colleague on S3, and S2 and S3 keep logging native VLAN complaints. Your job: make every inter-switch link a deliberate, documented 802.1Q trunk.

DevicePortRoleAddress
S1Gi0/0link to S2 Gi0/0SVI 99: 10.9.99.1/24
S2Gi0/0, Gi0/1links to S1 and S3SVI 99: 10.9.99.2/24
S3Gi0/1link to S2 Gi0/1SVI 99: 10.9.99.3/24
PC1S1 Gi1/0VLAN 10 SALES10.9.10.11/24
PC2S3 Gi1/0VLAN 10 SALES10.9.10.13/24
PC3S3 Gi1/1VLAN 20 ENGINEERING10.9.20.13/24

Topology: PC1 — S1 Gi1/0 · S1 Gi0/0 — S2 Gi0/0 · S2 Gi0/1 — S3 Gi0/1 · S3 Gi1/0 — PC2 · S3 Gi1/1 — PC3.

What you’ll practise

  • Explain DTP modes and predict whether two ports form a trunk
  • Configure static 802.1Q trunks and turn DTP off
  • Find and fix a native VLAN mismatch and explain VLAN hopping
  • Limit the VLANs on a trunk safely with the allowed list
  • Read every section of show interfaces trunk and describe VTP modes

The tasks

  1. Find out what DTP did
  2. Configure static trunks without DTP
  3. Fix the native VLAN mismatch
  4. Allow only the VLANs that are needed
  5. Read show interfaces trunk properly
  6. Know what VTP would do

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 802-1Q trunks - native VLAN and DTP6 nodes, 5 links. Every link is listed as text below the diagram.S1S2S3PC1PC2PC3Gi1/0eth0Gi1/0eth0Gi1/1eth0Gi0/0Gi0/0Gi0/1Gi0/1
6 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • S1 Gi0/0 to S2 Gi0/0
  • S2 Gi0/1 to S3 Gi0/1
  • S1 Gi1/0 to PC1 eth0
  • S3 Gi1/0 to PC2 eth0
  • S3 Gi1/1 to PC3 eth0
Nodes in 802.1Q trunks: native VLAN and DTP, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
S1Cisco IOSvL2viosl2-adventerprisek9-m.ssa.high_iron_202009291 vCPU, 1,024 MB
S2Cisco IOSvL2viosl2-adventerprisek9-m.ssa.high_iron_202009291 vCPU, 1,024 MB
S3Cisco IOSvL2viosl2-adventerprisek9-m.ssa.high_iron_202009291 vCPU, 1,024 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 CCNA 200-301 guided labs.

  3. Open 09 - 802-1Q trunks - native VLAN and DTP 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 Cisco. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.