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Multi-vendor troubleshooting lab 5 of 12

Spanning-tree interoperability with PVST MST and RSTP

Larkfield's campus is half way through a move to one MST region: one Cisco switch still runs Rapid PVST+, Arista and Aruba have typed their region differently, and the MikroTik only speaks RSTP. Find the boundaries, join the region, and prove the same digest on three vendors.

Run this lab

It needs Standard: its 7 nodes are set to 8 vCPU and 7,936 MB in total.

In your workspace: Shared, then Multi-vendor interoperability and troubleshooting guided labs, then 05 - Spanning-tree interoperability with PVST MST and RSTP

Run it on Standard from £5 a day

The free demo can’t run it: it has 6 vCPU and 8 GB, and this lab’s nodes need 8 vCPU and 7,936 MB together. Every lab plan includes every guided lab.

Level
Advanced
Time
About 80 minutes
Nodes need
8 vCPU, 7,936 MB
Smallest plan
Standard

The scenario

Larkfield has decided that the Leeds campus will run one MST region, called LARKFIELD, revision 1. SW1 has been converted. SW2 is still on Rapid PVST+ and was the old root for VLAN 10. The Arista and Aruba switches were set up by different contractors. The MikroTik CHR1 has a plain RSTP bridge and stays that way, as RouterOS bridges at this site aren't in the region.

Since the change, H1 can't reach H2, and SW1 shut its port to CHR1 as soon as the MikroTik came up.

DeviceRoleTarget
SW1Region rootRoot for instances 0 and 1 (priority 4096)
SW2Secondary rootRoot for instance 2 (priority 4096); 8192 for instances 0 and 1
EOS1, CX1AccessDefault priority, in the region
CHR1RSTP bridge, outside the regionDefault priority
MST settingValue
Region nameLARKFIELD (case matters)
Revision1
Instance 1VLAN 10
Instance 2VLAN 20
HostAddressAttached to
H110.10.0.101/24EOS1 Ethernet4, VLAN 10
H210.10.0.102/24CX1 1/1/3, VLAN 10
CHR110.10.0.4/24vlan10 on bridge br1

What you’ll practise

  • Read root, role and region on IOSvL2, EOS, AOS-CX and RouterOS
  • Recognise a PVST simulation inconsistency at an MST boundary
  • Compare MST configuration digests across vendors
  • Explain how each vendor expresses bridge priority
  • Recover a port shut by BPDU guard, and explain why RSTP on a router triggered it
  • Place the root for each MST instance

The tasks

  1. Give the hosts their addresses
  2. Map the tree as it is
  3. The PVST boundary between SW1 and SW2
  4. One region needs one digest
  5. BPDU guard against a router
  6. Read priority in each vendor's units

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 Spanning-tree interoperability with PVST MST and RSTP7 nodes, 8 links. Every link is listed as text below the diagram.SW1SW2EOS1CX1CHR1H1H2Ethernet4eth01/1/3eth0ether2Ethernet3ether1Gi0/2Gi0/11/1/1Ethernet1Gi0/1Gi0/0Gi0/01/1/2Ethernet2
7 nodes, with the interface names each link uses. On a narrow screen, scroll the diagram sideways.
Every link, as text
  • SW1 Gi0/0 to SW2 Gi0/0
  • SW2 Gi0/1 to CX1 1/1/1
  • CX1 1/1/2 to EOS1 Ethernet2
  • EOS1 Ethernet1 to SW1 Gi0/1
  • CHR1 ether1 to SW1 Gi0/2
  • CHR1 ether2 to EOS1 Ethernet3
  • EOS1 Ethernet4 to H1 eth0
  • CX1 1/1/3 to H2 eth0
Nodes in Spanning-tree interoperability with PVST MST and RSTP, with the image each runs and the vCPU and RAM it’s set to
NodeDeviceImage in Add NodeSet to
SW1Cisco IOSvL2viosl2-adventerprisek9-m.ssa.high_iron_202009291 vCPU, 768 MB
SW2Cisco IOSvL2viosl2-adventerprisek9-m.ssa.high_iron_202009291 vCPU, 768 MB
EOS1Arista vEOSveos-4.33.1.1F1 vCPU, 2,048 MB
CX1Aruba AOS-CX virtual switcharubacx-10.142 vCPU, 3,072 MB
CHR1MikroTik RouterOSmikrotik-7.14.21 vCPU, 256 MB
H1Alpine Linuxclbalpinebase-alpine-base-3-20-31 vCPU, 512 MB
H2Alpine 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 Multi-vendor interoperability and troubleshooting guided labs.

  3. Open 05 - Spanning-tree interoperability with PVST MST and RSTP 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, Cisco, CompTIA, Fortinet, HPE, Juniper Networks and MikroTik. The lab follows exam topics and isn’t vendor training material; vendor names identify the exams and the images in the workspace.