vtp pruning or allowed id vlan

Answered Question
Feb 2nd, 2009

I have 6509 for core switch and edge 3750. I have 30 vlans that distribuite with vtp and vtp pruning for avoid brodcast and another traffic generate to vlan. Which is the best solutions ? Vtp pruning or no vtp pruning but allowed only vlan that I need in the switch to the trunk port.

I have this problem too.
0 votes
Correct Answer by Istvan_Rabai about 7 years 11 months ago

Hi Roberto,

I don't think you will have problem with Rapid-PVST.

Its convergence time is much faster than that of the traditional STP.

Cheers:

Istvan

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ohassairi Mon, 02/02/2009 - 21:40

i think it is the same thing but with pruning the config will be dynamic.

if you don't choose pruning, in case of change in your vlan location you must do it manually in all your switches.

Istvan_Rabai Mon, 02/02/2009 - 22:02

Hi Roberto,

With VTP Pruning, broadcasts are not propagated on trunks for vlans that have no users on any ports on a specific switch.

But: STP (and BPDUs) is still running for the vlans pruned on the trunks.

With the use of the "switchport trunk allowed vlan" command you can disable entire vlans from trunks, thereby disabling user traffic and STP (and BPDUs) for those vlans.

When to use "switchport trunk allowed vlan":

If you do not plan to have users on a given switch in specific vlans in the future, then you can disable those vlans from respective trunks entirely with the "switchport trunk allowed vlan" command.

This will also economize some bandwidth and processor cycles for the switches.

But if you want to preserve those vlans on the trunks because users are likely to become alive on those vlans, then you can use pruning.

Cheers:

Istvan

Roberto Casagrande Mon, 02/02/2009 - 22:34

Hi Istvan,

O.K.

I suppose that I don't use vlan pruning, because I have 5 building and each building has 2 vlans 1 for voice(id 9) , 1 for data(id 22). So I have trunk allowed vlan 9,22.

Have I something problem with Rapid-pvst ? My root is core (6509) for any vlans.

thanks.

Correct Answer
Istvan_Rabai Tue, 02/03/2009 - 09:07

Hi Roberto,

I don't think you will have problem with Rapid-PVST.

Its convergence time is much faster than that of the traditional STP.

Cheers:

Istvan

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