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Arista EOS lab 3 of 20

MSTP and LACP port-channels

Turn a looped triangle of switches into a loop-free, load-shared layer 2 network: bundle the inter-switch links with LACP, design an MSTP region with one root per instance, and protect the edge with portfast, BPDU guard and root guard.

Run this lab

It needs Lite: its 4 nodes are set to 4 vCPU and 6,656 MB in total. That fits the free demo too.

In your workspace: Shared, then Arista EOS guided labs, then 03 - MSTP and LACP port-channels

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Level
Beginner
Time
About 60 minutes
Nodes need
4 vCPU, 6,656 MB
Smallest plan
Lite

The scenario

Northwind's office core is a triangle: two distribution switches (dist1, dist2) joined by two cables, and an access switch (acc1) with one uplink to each. Every link is a trunk for VLANs 10 and 20. A triangle is a loop, so spanning tree is doing all the work, and nobody chose where the root is. Your job: make the dist1–dist2 cables one logical link, then design MSTP so VLAN 10 prefers dist1 and VLAN 20 prefers dist2, and protect the edge.

DeviceInterfaceConnects toRole
dist1Ethernet1, Ethernet2dist2 Ethernet1, Ethernet2to become Port-Channel12
dist1Ethernet3acc1 Ethernet1trunk 10,20
dist2Ethernet3acc1 Ethernet2trunk 10,20
acc1Ethernet3h10access VLAN 10
SVI (for testing only, no routing)dist1dist2acc1h10
VLAN 10 · 10.10.10.0/24.1.2.3.11
VLAN 20 · 10.10.20.0/24.1.2.3–

What you’ll practise

  • Bundle two links into an LACP port-channel and verify the bundle
  • Configure an MSTP region (name, revision, VLAN-to-instance map) identically on every switch
  • Place the root bridge of each instance deliberately with priorities
  • Predict and verify port roles and states per instance
  • Protect edge ports with portfast and BPDU guard, and the distribution layer with root guard

The tasks

  1. Look at the loop spanning tree has blocked
  2. Bundle the dist1–dist2 links with LACP
  3. Design the MST region
  4. Place the roots
  5. Protect the edge and the core
  6. Prove both instances forward

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 MSTP and LACP port-channels4 nodes, 5 links. Every link is listed as text below the diagram.dist1dist2acc1h10Ethernet3eth0Ethernet3Ethernet1Ethernet3Ethernet2Ethernet1Ethernet1Ethernet2Ethernet2
4 nodes, with the interface names each link uses.
Every link, as text
  • dist1 Ethernet1 to dist2 Ethernet1
  • dist1 Ethernet2 to dist2 Ethernet2
  • dist1 Ethernet3 to acc1 Ethernet1
  • dist2 Ethernet3 to acc1 Ethernet2
  • acc1 Ethernet3 to h10 eth0
Nodes in MSTP and LACP port-channels, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
dist1Arista vEOSveos-4.33.1.1F1 vCPU, 2,048 MB
dist2Arista vEOSveos-4.33.1.1F1 vCPU, 2,048 MB
acc1Arista vEOSveos-4.33.1.1F1 vCPU, 2,048 MB
h10Alpine Linuxclbalpinebase-alpine-base-3-20-31 vCPU, 512 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 Arista EOS guided labs.

  3. Open 03 - MSTP and LACP port-channels 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 Arista Networks. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.