Thanks, how does this differ from VLAN pruning? I am not getting it clear from the Cisco documents.

Hi Friend,

If you clear vlan from the trunk interface it will not allow BPDUs also to pass for that vlan but VLAN pruning never stops BPDUs.

VTP pruning does not change a link's STP characterstics. BPDUs will still be broadcasted on the link in order to build a STP for that vlan and the trunk links still participate in STP convergence. Fot that reason it might be preferrable to clear the VLAN from the trunk link.

HTH

Ankur

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Thanks, so I assume that it would be enough that I allow only the management VLAN and the specific user VLAN and server farm VLAN (for the PC to communicate to server farm) on the trunk. Do I need to configure this at both side of the trunk? or it is fine to have on the distributing side alone? also if I want to allow the VLAN traffic again after clearing ID on trunk in CAT OS how can I do that?

I am looking for a doc with similar example in Cisco site and not getting it..

Hi Friend,

Yes it is always good practise to allow only those vlans on trunk which are there in network and which need to be passed on the trunk and not all vlans.

Also it is always good practice to restrict the vlan on trunk on both the sides instead of restricting on one side.

Have a look at this link for more details on how to configure the same.

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat3750/12235se/scg/swvlan.htm#wp1100014

HTH

Ankur

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Thanks, I had a chance to see this doc before but it describes configuration on a IOS based switch and not on CAT OS, can you let me know as how I can enable VLAN traffic to flow again after clearing on a cat 6509 trunk.

Hi Friend,

Here you go with the link which will guide you about the same on CATOS

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/sw_8_1/confg_gd/e_trunk.htm#wp1021347

If you have cleared some vlan on trunk and you want to add that back on the trunk allowed vlan list simpy issue this command

"set trunk mod/port

HTH

Ankur

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Thanks a lot for the quick response and guidance, I got it..

Rgs

Suresh