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Unable to create new VLANs

Since upgrading to VTP version 2 I am unable to create new VLANs on a 6509.

There are some 2980 access switches running CatOS, one of which is running in VTP server mode, I am able to create VLANs from the 2980 Ok and the new VLAN propogates to the 6509.

This is the error I see when trying to create a new VLAN in VLAN database mode from the 6509:

6509(vlan)#vlan 7

VLAN 7 added:

Name: VLAN0007

6509(vlan)#exit

VLAN 1003 parent VLAN missing

APPLY failed.

Use 'abort' command to exit

VLAN 1003 does exist on the 6509.

It seems likely that this is related to the upgrade to VTP version 2 as VLAN 1003 is the token ring VLAN introduced in version 2.

Any suggestions gratefully received.

3 REPLIES
Cisco Employee

Re: Unable to create new VLANs

Hi George,

The most common reason is if you have vtp version 2 configured. It is documented here about the issues here. Vlan 1003 is the token ring vlan.

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/12_1e/swconfig/vtp.htm#wp1029449

A VTP version 2-capable network device can operate in the same VTP domain as a network

device running VTP version 1 provided VTP version 2 is disabled on the VTP version

2-capable network device (VTP version 2 is disabled by default).

1) Do not enable VTP version 2 on a network device unless all of the network devices in the same VTP domain are version 2-capable. When you enable VTP version 2 on a network device, all of the version 2-capable network devices in the domain enable VTP version 2.

2) In a Token Ring environment, you must enable VTP version 2 for Token Ring VLAN switching

to function properly.

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat6000/12_1e/swconfig/vtp.htm#wp1032727

So what you need to do is disable vtp version 2.

HTH

Ankur

New Member

Re: Unable to create new VLANs

Thanks Ankur.

Couple more questions if I may:

Would I need to disable V2 mode across all the access switches as well as on the 6509?

Would you expect any downtime as a result of disabling V2 mode - eg if I disable it on the 6509 will the access switches not function in the VTP domain until they have been downgraded to VTP 1?

Cisco Employee

Re: Unable to create new VLANs

Hi George,

VTP version 2 is disabled by default on VTP version 2-capable switches. When you enable VTP version 2 on a switch, every VTP version 2-capable switch in the VTP domain enables version 2 and same happens when you disable vtp version 2 it will be disabled on all v2 capable switch.

You can only configure the version on switches in VTP server or transparent mode.

So you can disable v2 mode on your server and it will be done on all your clients and access switches which are in same vtp domain.

NOW because VTP is just to have vlan database synching across your network chnaging the version will not have any affect or downtime on your data network.

VTP version 1 and VTP version 2 are not interoperable on switches in the same VTP domain so till the time all switches have same VTP version the database synching will not happen for any new vlans or change or modification of exisitng vlans will not have affect on all switches.

So you can go ahead and change your switch back to version 1 and things will be ok.

HTH

Ankur

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