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Find free/no-longer-used VLANs

In a switched layer 2 network of all Cisco switches (2950/60s, 3550s etc) how can I determine what VLANs are no longer used?

What I mean by this is, VLAN 123 maybe defined on every switch, but if each switch has no access ports in this VLAN, then I would declare it no longer needed or used. However, the only way I can see to check in a given layer 2 environment would be to log into every switch and check if any ports are access ports for this VLAN (or read through the configs if they are to hand).

This seems very inefficient to me, especially in larger layer 2 networks. Does anyone know a faster, more efficient method?

  • LAN Switching and Routing
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1 ACCEPTED SOLUTION

Accepted Solutions

Find free/no-longer-used VLANs

Hi,

Why cant you use "sh vlan brief" on the layer 3 switch so that you can now what are the ports belongs to the specific vlan.

Please rate the helpfull posts.

Regards,

Naidu.

5 REPLIES

Find free/no-longer-used VLANs

Hi,

Why cant you use "sh vlan brief" on the layer 3 switch so that you can now what are the ports belongs to the specific vlan.

Please rate the helpfull posts.

Regards,

Naidu.

Bronze

Find free/no-longer-used VLANs

Show vlan brief will help, but if the vlan is part of a trunk, it won't show up in the list.

This is one of those unfortunate tasks you have to do the hard way.

Ven

Ven Taylor
New Member

Find free/no-longer-used VLANs

Hi guys,

Thanks for your replies. I think that the only way is to log into every switch as I have been doing an run "show vlan id" and check if the ports listed are the trunks for that switch.

Ah, I see, "sh vlan br" is a better command to run in this case. It doesn't show the trunk ports so that is useful, thanks

Find free/no-longer-used VLANs

Hi,

Glad that helped you at some level.
Please rate the helpfull posts which will be encourage others through this forum.


Please rate the helpfull posts.
Regards,
Naidu.

Silver

Find free/no-longer-used VLANs

maybe using cisco NMS Ciscowork or using scripting - TCL EEM

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Posted by WebUser Aku Apit

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