catos question

[glen.grant]

  Thought I would run this out there as i haven't tried this before .  Have a vlan I have to get rid on a catos dist layer switch  which runs across like 20 trunks . The dist switch is the vtp server .  If I just delete the vlan off the switch does it automatically pull it off all the trunks  or do you have to manually delete it off all the trunks anyway ?  This is a catos box   and most switches on the other ends are older 4006's with catos.

[Jon Marshall]

glen.grant wrote:
  Thought I would run this out there as i haven't tried this before .  Have a vlan I have to get rid on a catos dist layer switch  which runs across like 20 trunks . The dist switch is the vtp server .  If I just delete the vlan off the switch does it automatically pull it off all the trunks  or do you have to manually delete it off all the trunks anyway ?  This is a catos box   and most switches on the other ends are older 4006's with catos.

Glen

Just to clarify, do you mean the trunk is just allowing all vlans or do you mean you have actually specified what vlans can go across the link.

If the former it should remove it from all trunks.

Sorry if i misunderstood.

Jon

[glen.grant]

Hi Jon ,no we only allow specified vlans across the trunks . This was an old wireless vlan we used before we went controller based  wireless and now we don't need  but it is run across probably 20 trunks in this client/server  domain .  Just one of those things I have never really tried so I was just wondering if that vlan would automatically dissapear off the trunks if i do a "clear vlan x"  on the vtp server. i'm guessing maybe no seeing we allowed specific vlans across the trunks.  Also to clarify  we only specified the vlans on the trunks on one side (dist side)  , the client side everything is allowed .Probably will have to clear all those trunks of the allowed vlan  , oh well  .Just trying to save myself time ..  

[milan.kulik · Accepted solution]

Hi Glen,

which CatOS version are you running?

The 8.1 the Configuration guide says:

"When you delete a VLAN in VTP server mode, the VLAN is removed from all switches in the VTP domain."

See "Deleting a VLAN" in

http://www.cisco.com/en/US/docs/switches/lan/catalyst4000/8.1/configuration/guide/vlans.html#wp1020448

I believe clearing the VLAN from your VTP server is enough to make it disappear from the whole VTP domain (if your VTP works correctly).

Allowing/disallowing VLANs on a trunk is a different feature.

IMHO, the VLAN can remain allowed on a trunk (if specified by the set trunk ... command) but would not exist in the VLAN database on the switch.

Looking at the sh trunk command example in http://www.cisco.com/en/US/docs/switches/lan/catalyst4000/8.1/configuration/guide/e_trunk.html#wp1020589

you can see there are two output lines:

Vlans allowed on trunk

and

Vlans allowed and active in management domain

So I believe when you remove the VLANx from your VTP server it will become allowed but not active on the trunks.

BR,

Milan

[glen.grant]

Milan I agree after thinking about it a little .  Whether or not the vlan is created across the domain really has nothing to do whether its allowed across the trunk .  So if I want it off the allowed trunk statement I will have to manually remove it .  Thanks to everyone for  the input and have a good holiday...