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I have a Cisco Catalyst 3750 and 2960. I created VTP server in 3750 and deleted all useless vlans. When I connect 2960 (VTP status: Client) to 3750 VTP transferred all vlans which I deleted before.

What's wrong? Who can help?

  • After you delete unuseless vlans, did you save all configurations? You can check the VLAN database in flash memory to verify what wrong. – jfidel87 Jun 6 '14 at 13:24
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    gotta love VTP....everyone gets bit by this every once in a while ;) ...my best practice is to turn it off completely or leave it in transparent. good thing it didn't cause an outage in your case – knotseh Jun 7 '14 at 7:14
  • Did any answer help you? if so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you could provide and accept your own answer. – Ron Maupin Aug 6 '17 at 18:39
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Neither Native VLAN or VTP domain mismatch will cause this, as it normally impedes VTP propagation which you obviously do not have a problem with (your 3750 received and applied the VTP information from the 2960)

Check for VTP database version. If the 2960 had a higher version than the 3750, then it will be the one used.

This is the most likely thing to have happened... fiddling with your 3750 VTP config you might have reset it to Version 0, and not having touched the 2960 it has retained whichever version it had, resulting in the 3750 accepting the "more current" version of VTP config sent by the 2960.

Also be aware that "VTP Client" doesn't mean that it won't send VTP config, only that you cannot configure it directly. It can still send out VTP config that will replace your network if it's a higher version. VTP Transparent will not send out VTP config (will let pass through VTP info received though, just won't send its own info).

If you want to clear all vlans, now that they're synched, just delete them on the 3750 and the change should be propagated between both.

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  • Doh! Misread the original question. This is indeed the most likely answer. – YLearn Jun 6 '14 at 19:30
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The normal range of vlans is stored in the vlan.dat file in flash, deleting the vlans, the switch’s running config and even reloading doesn't get rid of those vlans. To permanently delete them try and erase the vlan.dat file from flash.

Use the command delete flash:vlan.dat

Source/further reading

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