How to manage Multiple Spanning Tree (MSTP) on Dell Networking Force10 DataCenter Switches

How to manage Multiple Spanning Tree (MSTP) on Dell Networking Force10 DataCenter Switches

This article explains how Multiple Spanning Tree Protocol (MSTP) is implemented on Dell Networking Force10 Switches.


Table of Contents

  1. Overview
  2. Enable MSTP
  3. Create Multiple Spanning Tree Instances
  4. Set Root Priorities
  5. Enable Edgeport
  6. Verify Configuration


  • MSTP is disabled by default.
  • The Dell Networking OS MSTP implementation is based on IEEE 802.1Q-2003 and inter operates only with bridges that also use this standard implementation.
  • When you enable MSTP, all ports in Layer 2 mode participate in MSTP.
  • MSTP is compatible with STP and RSTP.
  • Dell Networking OS supports only one MSTP region.
  • You can configure 64 MSTIs including the default instance 0 (CIST).

Enable MSTP

MSTP is not enabled by default. To enable MSTP globally, use the following commands.

When you enable MSTP, all physical, VLAN, and port-channel interfaces that are enabled and in Layer 2 mode are automatically part of the MSTI 0.

You can configure 64 MSTIs including the default instance 0 (CIST).


console(conf) # protocol spanning-tree mstp

  • Enable MSTP. PROTOCOL MSTP mode

console(config-mstp) # no disable

Creating Multiple Spanning Tree Instances

To create multiple spanning tree instances, use the following command.
A single MSTI provides no more benefit than RSTP. To take full advantage of MSTP, create multiple MSTIs and map VLANs to them.

console(conf) # protocol spanning-tree mstp
console(conf-mstp) # msti 1 vlan 100
console(conf-mstp) # msti 2 vlan 200-300
console(conf-mstp) # show config
protocol spanning-tree mstp
no disable
MSTI 2 VLAN 200-300

Set Root Priorities

MSTP determines the root bridge, but you can assign one bridge a lower priority to increase the probability that it becomes the root bridge.
To change the bridge priority, use the following command.

  • Assign a number as the bridge priority.


console(conf-mstp) # msti 1 bridge-priority 4096

A lower number sets the higher priority so that the bridge becomes the root bridge. The range is from 0 to 61440, in increments of 4096. The default is 32768.

Enable Edgeport

The EdgePort feature enables interfaces to begin forwarding traffic approximately 30 seconds sooner.

In this mode an interface forwards frames by default until it receives a BPDU that indicates that it should behave otherwise; it does not go through the Learning and Listening states.

console(conf) # interface te 0/1

console(conf-if-te 0/1) # spanning-tree mstp edge-port

Caution: Do not configure edgeport on interfaces that attach to another switch or network device.

Verify Configuration

console # show spanning-tree mst config

MST region name: Dell
Revision: 0
1 100
2 200-300

Dell Networking recommends that only experienced network administrators change MSTP parameters. Poorly planned modification of MSTP parameters can negatively affect network performance.

Article ID: HOW10397

Last Date Modified: 06/02/2016 09:47 AM

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