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New Member

root bridge have got a mac add that cannot be found

Hello,

I am facing an issue on one of my remote office on which the lan is switch is not the root bridge and in these delegations there are facing slow performance on which I m currently investigating.

after a simple diff between the config of some others remote offices and this particulare one I foud out that the switch is not the root bridge

DELXXXXsw001#show spanning-tree

VLAN0001   Spanning tree enabled protocol ieee  

Root ID   

Priority    32768            

Address    0012.a934.36e0            

Cost        4            

Port        21 (GigabitEthernet0/21)            

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

Bridge ID  Priority    32769  (priority 32768 sys-id-ext 1)             Address    001e.f6c1.0700             Hello Time  2 sec  Max Age 20 sec  Forward Delay 15 sec             Aging Time  300 sec

Interface          Role Sts Cost      Prio.Nbr Type

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

Gi0/1              Desg FWD 19        128.1    P2p

Gi0/2              Desg FWD 19        128.2    P2p Edge

Gi0/3              Desg FWD 4        128.3    P2p Edge

Gi0/4              Desg FWD 19        128.4    P2p Edge

Gi0/5              Desg FWD 4        128.5    P2p Edge

Gi0/6              Desg FWD 19        128.6    P2p Edge

Gi0/7              Desg FWD 4        128.7    P2p Edge Interface         

Role Sts Cost      Prio.Nbr Type

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

Gi0/8              Desg FWD 19        128.8    P2p Edge

Gi0/16              Desg FWD 19        128.16  P2p Edge

Gi0/17              Desg FWD 4        128.17  P2p Edge

Gi0/20              Desg FWD 19        128.20  Shr Edge

Gi0/21              Root FWD 4        128.21  P2p                

On this remote office they have plugged an ub or another exotic switch that seems to take the control of the spanning tree

However why I can see it on when I do a show mac add

e.g.

show mac add | i 0012.0a934.36e0

also can I just take the control of the spt by using the command

(config) t spann vlan X root primary???

thanks a lot

 

4 REPLIES

root bridge have got a mac add that cannot be found

Personally, I'd change the priority to 0 for your vlan:

spanning-tree vlan X priority 0

HTH,
John

*** Please rate all useful posts ***

HTH, John *** Please rate all useful posts ***

root bridge have got a mac add that cannot be found

You should probably also shut down interface g0/21. If someone has connected another switch that you don't control or know about, it should be disabled.

New Member

root bridge have got a mac add that cannot be found

Gents,

Thanks for your answers. However how to find this mac? I m sure it's coming from the port 21 (I see it on the show span output)

DELXXXXsw001#show spanning-tree

VLAN0001   Spanning tree enabled protocol ieee  

Root ID   

Priority    32768            

Address    0012.a934.36e0   

Please help

Kar

root bridge have got a mac add that cannot be found

sh mac address gig0/21 should give you all MAC addresses the switch sees on that interface.

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