STP Root Bridge

junshah22 · ‎07-26-2007

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

ankbhasi · ‎07-26-2007

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

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junshah22 · ‎07-26-2007

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 · ‎07-26-2007

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

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