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How to manage Per-VLAN Spanning Tree Plus (PVST+) on Dell Networking Force10 Switches

Summary: This article explains how Per-VLAN Spanning Tree Plus (PVST+) is implemented on Dell Networking Force10 Switches.

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Article Content


Instructions

  Topics Covered

 

  1. Configure Per-VLAN Spanning Tree Plus
  2. Configuring EdgePort
  3. Influencing Root Bridge Selection by Priority
  4. Verification Commands

 

Configure Per-VLAN Spanning Tree Plus

 

  Configure PVST+ is a four-step process.

  1. Configure interfaces for Layer 2
  2. Place the interfaces in VLANs
  3. Enable PVST+
  4. Optionally, for load balancing, select a non default bridge-priority for a VLAN.

 

Enabling PVST+

 

Command Line Example

 

Command

Purpose

Console# configure

Enters configuration level on the switch.

Console(config)# protocol spanning-tree pvst

Set the specific spanning-tree protocol.

Console(conf-pvst)#no disable

Enable spanning-tree globally.

 

 

 

Configuring EdgePort

 

It is recommended to configure any edge ports, ports that go to end devices such as printers, phones, servers, workstations, to be set up as Edge-Port.  A port in Edge-Port will move directly to forwarding state when the link comes up without waiting for the forward-time delay.

 

Command Line Example 

 

 

Command

Purpose

console# configure

Enter configuration level on the switch.

console(config)# interface te 0/1

Enter the desired physical port interface.

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

Enables Edge-port on the interface.

console (conf-if-te-0/1)# no spanning-tree pvst edge-port

Disables Edge-port on the interface.

 

 

Influencing PVST+ Root Selection

 

The bridge with the lowest bridge value for bridge priority is elected root. Because all bridges use the default priority (until configured otherwise), the lowest MAC address is used as a tie-breaker. To increase the likelihood that a bridge is selected as the STP root, assign bridges a low non-default value for bridge priority.

The following per-VLAN spanning tree illustration changes the bridge priority of each bridge so that a different forwarding topology is generated for each VLAN. This behavior demonstrates how you can use PVST+ to achieve load balancing.

 

Figure 1 - Load Balancing with PVST+

 HOW10410_en_US__1PVST+ Load Balancing

 

 

To assign a bridge priority, use the following command.

 

  • Assign bridge priority PROTOCOL PVST mode

 

console(conf-pvst)# vlan X bridge-priority  <0-61440>

The range is from  0-61440.

The default  is 32768.

 

Command Line Example

 

Command

Purpose

Console# configure

Enters configuration level on the switch.

Console(config)# protocol spanning-tree pvst

Set the specific spanning-tree protocol.

Console(conf-pvst)# vlan 100 bridge-priority 4096

Set VLAN spanning-tree priority.  Range <0 – 61440>.  In increments of 4096.

 

 Verification Commands

 

Command

Purpose

Console# show spanning-tree pvst vlan 100

View VLAN level spanning tree settings.

Console# show spanning-tree pvst

View global spanning-tree settings.

 

 

 

 

 

 

Article Properties


Affected Product

Force10 S60-44T

Last Published Date

18 Mar 2021

Version

4

Article Type

How To