VTP change

[londint]

I am connecting up a 2950 to a 3550, which in turn connected up to a 6509. The 6509 is the VTP Server and all others are clients.

When I connect up the 2950 to the 3550 as a chain and the vtp set to client, it always changes it to Transparent thereby I am not able to download any of the vlans from the 6509.

There are no vlans on the 2950 except for the default.

So what is wrong? Pls help, as this is urgent.

Thanks

[amit-singh]

Hi,

How many Vlans are you running on your 6509? 2950 switch supports 250 vlans and if you are running more than that then it will change itself to trasparent mode.

HTH,

-amit singh

[glen.grant]

As the previous poster said you are probably allowing all vlans across the trunk which the 2950 cannot handle . On the server 6509 , manually prune(clear trunk X/X) off any vlan that you do not need to run on the 3550 or the 2950 . Doubt you need 250 vlans running on 2 switches .

[londint]

Thanks.

Lots of VLANs. This is the set up I have

6509 <<<--->>> 3550 <<<--->>>>2950. So the 2950 is not connected directly t the 6509. We virtually have all the VLANs on the 6509 on the 3550 and this worked fine. On the 3550 and 2950 interfaces I did have punning and allowed for only 5 vlans but still the same issue.

Which one should I have (punning or allowed). As when I check sh interface trunk on the 3550, I see all the VLAN and on the 2950, I only see default vlan 1.

Thanks

[sebastian.wiegand]

hi londint,

how are these switches connnected?

Have u checked the VTP version information?

thx

Sebastian

[Josef Oduwo]

An OTP question: would interaction between the two VTP versions cause the 2950 to go transparent?

Josef.

[londint]

The vtp versions are the same. They are connected using an ethernet cross over cable and the interfaces configured for trunking 802.1q.

Thanks

[amit-singh]

Hi,

Pruning has all different concept and that will not help here. You have to manually remove the vlans over the trunk as suggested by Glan. You have to use commands to manually allow that.

switchport trunk allowed < vlan_num>

Switchport trunk remove

Let me know if you have any concerns.

HTH,

-amit singh

[milan.kulik]

Hi,

IMHO, if switch moves itself to VTP transparent mode, disabling VLANs on trunk will not help.

(It would help with STP instances problem, but that's another story.)

This is one of the most stupid Cisco IOS features - exceeding the number of VLAN configured (not active!) in the VLAN database moves the switch to transparent mode and there is NO WAY to prevent it.

The number of "supported" VLANs is 64 for 2950 SI and 250 for 2950 EI.

So if you have more than 64 VLANs configured in your VTP domain, your 2950 running SI IOS will be moved to transparent mode and you have no chance to prevent this behaviour.

See http://www.cisco.com/univercd/cc/td/doc/product/lan/cat2950/12122ea2/2950scg/swvlan.htm

for details.

Regards,

Milan