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Community Member

Spanning-tree Vlan

Hi all,

im using 2960 24 port switch. it has rapid-pvst, i given uplink to SG-300 from G0/2.

the out put of Sh int trunk is given below.

Port        Mode             Encapsulation  Status        Native vlan

Fa0/22      on               802.1q         trunking      1

Fa0/23      on               802.1q         trunking      1

Fa0/24      on               802.1q         trunking      1

Gi0/1       on               802.1q         trunking      1

Gi0/2       on               802.1q         trunking      1

Port        Vlans allowed on trunk

Fa0/22      1-4094

Fa0/23      1-4094

Fa0/24      1-9,11-4094

Gi0/1       1-4094

Gi0/2       1-4094

Port        Vlans allowed and active in management domain

Fa0/22      1-2,4-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Fa0/23      1-2,4-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Fa0/24      1-2,4-9,11-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Gi0/1       1-2,4-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Gi0/2       1-2,4-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Port        Vlans in spanning tree forwarding state and not pruned

Fa0/22      1-2,4-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Fa0/23      1-2,4-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Fa0/24      1-2,4-9,11-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Gi0/1       1-2,4-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Gi0/2       1-2,4-9,11-12,14-15,20,25-28,30-32,35,38,40,42,50-58,60,70,80,178,201,203

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

Here i have a doubt in Spannig tree forwarding state some vlans are not forwarded on Gi0/2

Why? and can i forwarde those vlans on gi0/2? how ?

Thanks

in advance

7 REPLIES
Purple

Spanning-tree Vlan

Hi,

Can you post sh spanning-tree vlan 10 output.

Regards

Alain

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Community Member

Spanning-tree Vlan

Hi alain,

below is the spanning tree vlan 10,.. for security reseaons i removed mac--

VLAN0010

  Spanning tree enabled protocol rstp

  Root ID    Priority    32778

             Address    

             Cost        4

             Port        25 (GigabitEthernet0/1)

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

  Bridge ID  Priority    32778  (priority 32768 sys-id-ext 10)

             Address    

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

             Aging Time  300 sec

Interface           Role Sts Cost      Prio.Nbr Type

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

Fa0/22              Desg FWD 19        128.22   P2p

Fa0/23              Desg FWD 19        128.23   P2p Peer(STP)

Gi0/1               Root FWD 4         128.25   P2p Peer(STP)

Gi0/2               Altn BLK 4         128.26   P2p Peer(STP)

thanks in advance

Purple

Spanning-tree Vlan

Hi,

Gi0/2               Altn BLK 4         128.26   P2p Peer(STP)

So you've got the answer for this vlan and I suspect it is the same for others.

Can you post your topology.

Regards

Alain

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VIP Purple

Re: Spanning-tree Vlan

Hello

See if these vlans highlighted are in the vtp database of this switch, Possible reason why you see the below output, is that there are being allowed on the trunk interface but don't exist.

Port        Vlans allowed and active in management domain

Gi0/2       1-2,4-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Port        Vlans in spanning tree forwarding state and not pruned

Gi0/2       1-2,4-9,11-12,14-15,20,25-28,30-32,35,38,40,42,50-58,60,70,80,178,201,203

Sh vlan brief

res

Paul

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Thanks.

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Purple

Spanning-tree Vlan

Hi Paul,

As you can see from sh spanning-tree vlan 10 output this vlan 10 is in blocking mode(alternate port) so it does exist on the switch.

All vlans showed in upper output do exist on the switch and are active but they don't appear in lower output because they may be pruned(vtp pruning) or not in fwding state(stp) and here for vlan 10 this was the case and I think it must be the same for others.

Regards

Alain

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Community Member

Spanning-tree Vlan

Hi paul and alain

my both switches are in RSTP MODE. but here SG-300 using RSTP and 2960 using rapid-pvst. its taking the spanning tree root on Gi0/1 for some vlans in 2960. Gi0/2 is up link to SG-300 , all vlans on the trunk.. but spanning-tree not forwarding those vlans on G0/2. can i root those vlan to gi0/2?

Port        Vlans in spanning tree forwarding state and not pruned

Fa0/22      1-2,4-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Fa0/23      1-2,4-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Fa0/24      1-2,4-9,11-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205

Gi0/1       1-2,4-12,14-15,20,23-28,30-32,35,38,40,42,50-60,70,80,178,198-201,203-205


Gi0/2       1-2,4-9,11-12,14-15,20,25-28,30-32,35,38,40,42,50-58,60,70,80,178,201,203

Hall of Fame Super Blue

Re: Spanning-tree Vlan

You don't want to set root for those vlans on that port.

Alain has asked what your topology is and that question needs answering because it might explain what is happening.

Is this the only link from SG-300 to the 2960 switch ?

Is that the only link from the new switch to any other switch in your setup ?

We need to understand how you have connected all the switches to understand why the link is blocking.

Jon

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