Spanning tree issue

sateeshk10 · ‎11-25-2008

Hi,

I have configured core sw as root bridge for VLAN 64 (4096).

Core sw config:

spanning-tree vlan 64 priority 4096

I have checked the root bridge for VLAN 64 from access switch

ACC-SW1#sh spanning-tree vlan 64

VLAN0064

Spanning tree enabled protocol rstp

Root ID Priority 4160

Address 0012.00d0.1100

Cost 3

Port 56 (Port-channel1)

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

Bridge ID Priority 32832 (priority 32768 sys-id-ext 64)

Address 0023.ab2a.c280

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

Aging Time 300

Interface Role Sts Cost Prio.Nbr Type

---------------- ---- --- --------- -------- --------------------------------

Po1 Root FWD 3 128.56 P2p

My question is why it is showing rott bridge as 4160..it suppose to show 4096 right??

Regards

sateesh

massimiliano.serafino · ‎11-25-2008

Hi,

The priority is Priority 4096 + Vlan ID=4096 + 64.

That is the extended system id.

If you want disable it, you must issue the command:

no spanning-tree extend system-id

I hope this helps.

Best regards.

Massimiliano.

sateeshk10 · ‎11-25-2008

Hi,

Thanks for prompt response. I have tried in the same way..But still its showing like that only..

Regards

sateesh

massimiliano.serafino · ‎11-25-2008

Hi,

You have to issue this command on root bridge.

Best regards.

Massimiliano.

sateeshk10 · ‎11-25-2008

HI,

I have issued the command on root bridge only and rebooted also

Still its like that..

Regards

sateesh