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CCNP ENCOR lab 6 of 36

Multiple Spanning Tree (MST)

Replace per-VLAN spanning trees with MST: one region, two instances that carry different VLANs on different uplinks, planned roots per instance, and a hands-on look at what happens at a region boundary.

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 CCNP ENCOR 350-401 guided labs, then 06 - Multiple Spanning Tree - MST

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

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

The scenario

Fernhill Freight plans to add dozens of VLANs to the warehouse block. With Rapid PVST+, every VLAN runs its own spanning tree with its own BPDUs and its own CPU cost, though only two different topologies are needed: "via DSW1" and "via DSW2". The design team has chosen MST (802.1s):

  • Region FERNHILL, revision 1, on all four switches.
  • MSTI 1: VLANs 10 and 99, root DSW1, backup root DSW2.
  • MSTI 2: VLANs 20 and 30, root DSW2, backup root DSW1.
  • The IST (instance 0, everything else) is rooted on DSW1.

The switches currently run Rapid PVST+ with default priorities, and the trunks carry all VLANs.

DeviceLinksNotes
DSW1Gi0/0 → DSW2, Gi0/1 → ASW1, Gi0/2 → ASW2SVIs 10.10.10.2, 10.10.20.2, 10.10.99.2
DSW2Gi0/0 → DSW1, Gi0/1 → ASW1, Gi0/2 → ASW2Vlan99 10.10.99.3
ASW1Gi0/1 → DSW1, Gi0/2 → DSW2, Gi1/0 → PC1 (VLAN 10)Vlan99 10.10.99.11
ASW2Gi0/1 → DSW1, Gi0/2 → DSW2, Gi1/0 → PC2 (VLAN 20)Vlan99 10.10.99.12
PC1 / PC210.10.10.10 / 10.10.20.10gateways on DSW1 (.2)

Topology: the same square as lab 5. DSW1 and DSW2 are linked; each access switch has one uplink to each.

What you’ll practise

  • Explain why MST maps many VLANs to a few spanning-tree instances
  • Configure an MST region (name, revision, VLAN-to-instance map) consistently on every switch
  • Place the root of the IST and of each MSTI
  • Recognise a region boundary and the effect of a configuration mismatch
  • Verify MST roles, costs and the configuration digest

The tasks

  1. Why MST?
  2. Define the region on every switch
  3. Place the roots
  4. Check the forwarding paths
  5. Break the region on purpose

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 Multiple Spanning Tree - MST6 nodes, 7 links. Every link is listed as text below the diagram.DSW1DSW2ASW1ASW2PC1PC2Gi1/0eth0Gi1/0eth0Gi0/1Gi0/1Gi0/2Gi0/2Gi0/0Gi0/0Gi0/2Gi0/1Gi0/1Gi0/2
6 nodes, with the interface names each link uses.
Every link, as text
  • DSW1 Gi0/0 to DSW2 Gi0/0
  • DSW1 Gi0/1 to ASW1 Gi0/1
  • DSW1 Gi0/2 to ASW2 Gi0/1
  • DSW2 Gi0/1 to ASW1 Gi0/2
  • DSW2 Gi0/2 to ASW2 Gi0/2
  • ASW1 Gi1/0 to PC1 eth0
  • ASW2 Gi1/0 to PC2 eth0
Nodes in Multiple Spanning Tree (MST), with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
DSW1Cisco IOSvL2viosl2-adventerprisek9-m.ssa.high_iron_202009291 vCPU, 768 MB
DSW2Cisco IOSvL2viosl2-adventerprisek9-m.ssa.high_iron_202009291 vCPU, 768 MB
ASW1Cisco IOSvL2viosl2-adventerprisek9-m.ssa.high_iron_202009291 vCPU, 768 MB
ASW2Cisco 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

How to open this lab

  1. Sign in to your workspace at lab.cloudlabbox.com.

  2. In File Manager, open Shared, then the folder CCNP ENCOR 350-401 guided labs.

  3. Open 06 - Multiple Spanning Tree - MST 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.