STP Root Bridge

Unanswered Question
Jul 26th, 2007
User Badges:

Hello all,


If we have 4 switches connected with each other with Trunk ports.


You have access only on one switch .....how can you see Root Bridge...and its priority....


Show spanning-tree will display bridge ID .....my question is this how can you see bridge ID and Bridge Priority of other switches connected in the network while having access to only one switch.


Regards,

Jun

  • 1
  • 2
  • 3
  • 4
  • 5
Overall Rating: 0 (0 ratings)
Loading.
ankbhasi Thu, 07/26/2007 - 03:35
User Badges:
  • Cisco Employee,

Hi Jun,


"sh spanning-tree " will display you root switch priority and root switch address also.


Switch#sh spanning-tree vlan x


VLAN00XX

Spanning tree enabled protocol ieee

Root ID Priority 32790

Address xxxx.xxxx.xxxx

Cost 4

Port 23 (GigabitEthernet1/0/23)

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec


Bridge ID Priority 32790 (priority 32768 sys-id-ext 22)

Address xxxx.xxxx.xxxx

Hello Time 2 sec Max Age 20 sec Forward Delay 15 sec

Aging Time 300


If you see the output the first few lines give you details about root switch mac address and priority.


HTH


Ankur


*Pls rate all helpfull post


junshah22 Thu, 07/26/2007 - 04:31
User Badges:

Thanks for your reply.


But it is not showing who is the Root Bridge,


secondly I asked, how can I check Root ID and Priority of other connected switches..


Regards,

Jun

ankbhasi Thu, 07/26/2007 - 05:46
User Badges:
  • Cisco Employee,

Hi Jun,


It is showing you the mac address of the root bridge so now it is left on you to find out that mac address belong to which switch which you can track down easily following the port numbers through mac address table.


Coming to your second doubt switch will not tell you the root id and priority of all connected switches. Just imagine how much big database switch need to maintain if it has to report you the root id and priority of all the connected switches.


It will always update you about itself and about root bridge.


HTH


Ankur


*Pls rate all helpfull post

Actions

This Discussion