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Community Member

Phantom VLANs on CAT 6500 running CatOS 7.6(1)

When the SUP 2 module in slot 1 is the active SUP, we intermittently notice PHANTOM VLANs 2093 and 2109 on this switch. (See attachments to see hwat I mean). When this happens we have intermittent loss of connectivity to servers on this switch. When these phantom VLANS disapper connectivity to servers from this s witch is fine. When SUP in slot 2 is active we never see this problem and that is how the switch has been now running for months. Could this be a H/W problem with the SUP in slot 1. We have two CAT 6500 switches with similar configs and both are configured as VTP Transparent. But only on one of the CAT 6500 we see these unconfigured Phantom VLANs appear and disappear.

Hall of Fame Super Blue

Re: Phantom VLANs on CAT 6500 running CatOS 7.6(1)


It sounds like your vlan.dat file in nvram is inconsistent on your sup module in slot 1.

What happens if you try to delete the phantom vlans when they show up in the config ?

One thing you could try is to delete your vlan.dat and copy across the one from the working supervisor.



Community Member

Re: Phantom VLANs on CAT 6500 running CatOS 7.6(1)


Thanks for your reply.

Is the vlan.dat file separate file on each SUP module.

Anyway - to follow you recommendation, can you please point me to a link and give me a brief pocedure on how I can delete vlan.dat on SUP module in slot 1, while SUP module in slot 2 is in production. After deleting the vlan.dat in slot 1 SUP will it automatically copy the good vlan.dat file from slott 2. If not how do i go about copying the good vlan/dat from slot 2 to slot 1 SUP.

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