Controller Based WLANs

How do I determine the root bridge for a controller?

Product and Software: This article applies to all Aruba controllers and ArubaOS versions.

 

The root bridge for a spanning tree domain can be determined by issuing the "show spanning-tree" command. At the time this article was written, no WebUI option exists to check spanning tree status.

Example:
This example uses ArubaOS 3.4.0.2, which supports RSTP (Rapid Spanning Tree Protocol). By default the controller uses RSTP and reverts to standard spanning tree on a port if it is connected to a switch/bridge running standard spanning tree.

(Aruba) #show spanning-tree

Spanning Tree is executing the IEEE compatible Rapid Spanning Tree protocol
Bridge Identifier has priority 32768, address 00:0b:86:00:44:20
Configured hello time 2, max age 20, forward delay 15
Current root has priority 0, address 00:01:e8:d5:a3:6d
Topology change flag is not set , detected flag not set , changes 7755
Times: hold 1, topology change 35 hello 2, max age 20, forward delay 30
Timers: hello 0, notification 0
Last topology change: 0 days, 0 hours, 0 mins, 0 secs

In this example it can be seen that the current root switch has a priority of 0 and its address is 00:01:e8:d5:a3:6d. If the switch on which command is being run is the root, it will claim itself as the root in the output. If spanning tree is disabled, it will list the configuration parameters as shown next. It can be seen that spanning tree mode is RSTP.

(Aruba) #show spanning-tree

Spanning Tree is not currently active
The following parameters have been configured
Stp Status : Disabled
Protocol : IEEE
Max Age (sec) : 20
Hello Time (sec) : 2
Forward Delay (sec) : 15
Bridge Priority : 32768
Mode : RSTP (802.1w)

Versions of ArubaOS earlier than 3.4 will have spanning tree mode of 802.1d because RSTP is supported in versions after ArubaOS 3.4.

Example from a switch running ArubaOS 3.3.2.17:

(SD-SC2M) (config) #show spanning-tree

Spanning Tree is executing the IEEE compatible Spanning Tree protocol
Bridge Identifier has priority 32768, address 00:0b:86:00:44:00
Configured hello time 2, max age 20, forward delay 15
We are the root of the spanning tree
Topology change flag is not set , detected flag not set , changes 1
Times: hold 1, topology change 35 hello 2, max age 20, forward delay 15
Timers: hello 1, notification 0
Last topology change: 0 days, 0 hours, 5 mins, 9 secs

(SD-SC2M) #show spanning-tree

Spanning Tree is not currently active
The following parameters have been configured
Stp Status : Disabled
Protocol : IEEE
Max Age (sec) : 20
Hello Time (sec) : 2
Forward Delay (sec) : 15
Bridge Priority : 32768
Mode : STP (802.1d)

Version History
Revision #:
1 of 1
Last update:
‎06-30-2014 08:06 PM
Updated by:
 
Labels (1)
Contributors
Search Airheads
Showing results for 
Search instead for 
Did you mean: 
Is this a frequent problem?

Request an official Aruba knowledge base article to be written by our experts.