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Tim Glen
Cisco Employee

VTP issue....

Hi All

I’m running into an odd problem with VTP.

I have a problem that I cannot figure out…  This problem is occurring in several wiring closets and is easily reproducible.

Core switch is a 6509 with Sup2 running hybrid mode. 

Core runs in VTPv2 Server mode with lots of VLANs.

Access switches are 2960S’s or 3550’s.

Access switches were originally configured as VTP client mode.

The Access switches have all the VLANs on them, and all run an STP instance for each VLAN.  Most Access switches only need 3 or 4 VLANs not 50+….  So I configured VTP mode transparent, and deleted all the unnecessary VLANs on the Access switches.

Here’s the problem….

VLAN 10 is on the Access Switch.  VLAN 10 STP root is configured on the Core. VLAN 10 is used for both PC’s, printers,  web cams etc . 

None of the PC’s exhibits any problems.  Some of the printers and web cams, not all of them,  in the same VLAN will work for a few minutes after an initial power on and then will go offline and become un-pingable. However if I setup a persistent ping to those same devices they will never go off line.

If I re-enable VTP client on the Access switches the problem will not occur. 

Then I configure VTP transparent and the problem occurs again.

Any ideas or tips would be greatly appreciated.



Eugene Lau
Cisco Employee

Hi Tim,

Just a quick reply - can you verify whether you have vtp pruning enabled on the server? If yes, please disable if you are running a mixed VTP server/client/transparent environment.

Note that disabling vtp pruning typically has no impact on STP or traffic but you could see an increase in bandwidth utilisation on certain trunks.