Description

To ensure a healthy Spanning-Tree Network, all devices should run the same flavor of the Spanning-Tree Protocol (STP).

This article is part of KB22774 - Resolution Guide - EX - Troubleshoot Spanning Tree [juniper.net] .

Symptoms

Verify that all devices in the Spanning-Tree Network are running the same STP flavor.

Switches, in a Spanning-Tree scenario, should run the same Spanning-Tree flavor to have a loop-free network.

Solution

Display the Enabled Spanning-Tree Protocol.

To verify if the Spanning-Tree Protocol is running on a device, issue the following command: 

user@switch> show spanning-tree bridge

STP bridge parameters
Context ID : 0
Enabled protocol : RSTP   <-------
Root ID : 32768.28:c0:da:3d:50:40
Hello time : 2 seconds
Maximum age : 20 seconds
Forward delay : 15 seconds
Message age : 0
Number of topology changes : 2
Time since last topology change : 3218 seconds
Topology change initiator : ge-0/0/4.0
Topology change last recvd. from : 2c:6b:f5:8b:23:04
Local parameters
Bridge ID : 32768.28:c0:da:3d:50:40
Extended system ID : 0
Internal instance ID : 0

In the above output, the switch has been enabled for RSTP - Rapid Spanning Tree Protocol. The same command can be issued on all Juniper EX switches to verify the Spanning Tree Protocol.

For an overview of the supported Spanning Trees, refer to Spanning-Tree Protocols User Guide .

For more information about the show spanning-tree bridge command, refer to show spanning-tree bridge .

Enable/Disable Spanning-Tree Protocol.

To configure Spanning-Tree, use the command: 

user@switch# set protocols <spanning-tree flavor>

The Spanning-Tree flavors available in EX switches include:

  • STP

  • RSTP

  • MSTP

  • VSTP

For more details on configuring Spanning-Tree, refer to the following:

To delete a Spanning-Tree Protocol that is already configured, use the command: 

user@switch# delete protocols <undesired spanning-tree flavor>
Note: RSTP is the Spanning-Tree flavor enabled by default on EX Series switches. STP cannot be configured on switches that are configured for Redundant Trunk Group (RTG). For more information about RTG, refer Understanding Redundant Trunk Links on EX Series Switches .

 

Modification History

2022-03-11: Article updated to reflect valid and current links and information