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MikroTik MTCNA lab 18 of 19

Troubleshooting: VLANs and bridges

The hotel VLAN network from lab 7 has been 'tidied up' by a contractor and now staff, guests and the switches' management are each broken in a different way. Use the bridge's own tables to find four VLAN faults and fix them.

Run this lab

It needs Lite: its 6 nodes are set to 6 vCPU and 3,840 MB in total. That fits the free demo too.

In your workspace: Shared, then MikroTik MTCNA RouterOS v7 guided labs, then 18 - Troubleshooting - VLANs and bridges

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

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Level
Advanced
Time
About 50 minutes
Nodes need
6 vCPU, 3,840 MB
Smallest plan
Lite

The scenario

The hotel network from lab 7 worked until a contractor "tidied up the switch configs" over the weekend. Reception now reports four problems:

  • Staff1 (reception PC, SW1 ether3) can't reach anything, not even its gateway.
  • Staff2 (back office, SW2 ether2) can't reach its gateway either.
  • Guest1 (SW1 ether4) has no Internet: it can't reach its gateway.
  • Fernvale's monitoring says SW2 stopped answering on 192.168.99.3, although SW1 (.2) still answers.

The design hasn't changed: VLAN 10 Staff 192.168.10.0/24, VLAN 20 Guest 192.168.20.0/24, VLAN 99 Management 192.168.99.0/24, GW routing on a stick with .1 in each VLAN.

DevicePortShould be
SW1ether1, ether2trunks: 10, 20, 99 tagged
SW1ether3 / ether4access VLAN 10 / VLAN 20
SW2ether1 / ether2trunk: 10, 20, 99 tagged / access VLAN 10
SW1, SW2bridge1 (CPU)tagged in VLAN 99, addresses .2 and .3
GWvlan10, vlan20, vlan99 on ether2VLAN IDs 10, 20, 99

What you’ll practise

  • Read bridge ports, the bridge VLAN table and current members to find VLAN faults
  • Tell a wrong PVID from a missing tagged member
  • Find why a switch's management address is unreachable while users work
  • Check a router-on-a-stick's VLAN IDs
  • Use the host table's VID column as evidence

The tasks

  1. Staff1 can't reach its gateway
  2. Staff2 can't reach its gateway
  3. Guests have no gateway
  4. SW2's management address is dead

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 - VLANs and bridges6 nodes, 5 links. Every link is listed as text below the diagram.GWSW1SW2Staff1Guest1Staff2ether3eth0ether4eth0ether2eth0ether2ether1ether2ether1
6 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • GW ether2 to SW1 ether1
  • SW1 ether2 to SW2 ether1
  • SW1 ether3 to Staff1 eth0
  • SW1 ether4 to Guest1 eth0
  • SW2 ether2 to Staff2 eth0
Nodes in Troubleshooting: VLANs and bridges, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
GWMikroTik RouterOSmikrotik-7.14.21 vCPU, 256 MB
SW1MikroTik RouterOSmikrotik-7.14.21 vCPU, 256 MB
SW2MikroTik RouterOSmikrotik-7.14.21 vCPU, 256 MB
Staff1VPCS hostBuilt in to EVE-NGCounted as 1 vCPU, 1,024 MB
Guest1VPCS hostBuilt in to EVE-NGCounted as 1 vCPU, 1,024 MB
Staff2VPCS 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 MikroTik MTCNA RouterOS v7 guided labs.

  3. Open 18 - Troubleshooting - VLANs and bridges 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 MikroTik. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.