What would cause new vlans to not talk to each other?

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Sep 28th, 2007
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I have 2 VTP Servers, each with a differnet name, connected via trunk port.

I added a VLAN on each VTP Server, but can not ping either VLAN interface that was just added.

Both interfaces show as being up.

The L2 VTP Server has just been provisioned as we are adding a switch to form a stack this weekend.

So being proactive, I figured I would create the a new VLAN to verify connectivity between the two new VLAN interfaces, however, they do not ping.

Can anyone advise on how to resolve?

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rwamstutz Fri, 09/28/2007 - 12:12
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all vlans are allowed. The L2 Switch has recently been provisioned for a switch to be added to it, does that do anythign?

Calin Chiorean Mon, 10/01/2007 - 03:46
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Hello all!

From my knowledge if you have 2 VTP Servers and the same domain configured for both, then if you configure a VLAN on one of the VTP Server, then it should be propagate automatically on the other one.If it act like this than the VTP Servers function OK.

Can you check this?



paul.matthews Mon, 10/01/2007 - 04:05
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Could you add your configs? That would help us see if we can see any discrepancies.


Kevin Dorrell Mon, 10/01/2007 - 05:13
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If the VTP domains are different, then you must force the trunk with switchport mode trunk at both ends. You might want to add switchport nonegotiate for good measure to stop any DTP packets being sent out at all.

As far as I know, DTP will not negotiate a trunk dynamically across two different VTP domains. You might like to confirm that with a show int trunk.

(OTOH, if the domain names are the same and the VTP mode is transparent, then dynamic trunk negotiation will work, even if the VLAN lists will not be synchronised.)

Kevin Dorrell


Edison Ortiz Mon, 10/01/2007 - 10:27
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Where are you pinging the Vlans from ? A workstation or from the switch CLI ?

Can we see the 'show ip int bri | ex una' output ?


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