VTP client to transpartent on Catalyst 6000

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Jun 17th, 2007
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Hi,


I have two Catalyst 6509 switches running CatOS 7.6(7) in VTP client mode.


Obviously, no VLAN definition appears in their configuration since their vlan database can only be populated through VTP updates. At that stage I have two questions:

1. where is the vlan database stored (the one I see doing a 'show vlan') if not in the config file ?


2. if it's stored in RAM (rather than NVRAM) what whould happen if I reboot the switches, would they loose their vlan configuration ?


For some reasons I need to move them to transparent mode. My main concern is what would happen just after I change their config from 'vtp client mode' to 'vtp tranparent mode' in terms of vlan database ?

Would they loose their vlan database ?

Can I overwrite all existing vlans with a hardcoded (in config) definition of these vlans ?


Many thanks for your help.

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rajinikanth Sun, 06/17/2007 - 22:57
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Hi,


The VLAN configuration is stored in the vlan.dat file, which is stored in nonvolatile memory. You can cause inconsistency in the VLAN database if you manually delete the vlan.dat file.


When the switch boots, if the VTP domain name and VTP mode in the startup-config and vlan.dat files do not match, the switch uses the configuration in the vlan.dat file.


If the switch is in VLAN transparent mode, use the copy running-config startup-config command to save the VLAN configuration to the startup-config file. After you save the running configuration as the startup configuration, the show running-config and show startup-config commands display the VLAN configuration.


http://www.cisco.com/en/US/docs/switches/lan/catalyst4500/12.1/19ew/configuration/guide/vlans.html#wp1020887


HTH


Raj

arnaud.chiaberge Sun, 06/17/2007 - 23:26
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Hi Raj,


Thanks for your answer but I'm not sure it really applies to my configuration: as I said I'm running CatOS (v7.6) on Catalyst 6500 chassis.


There is no vlan.dat file.


So all my initial questions are still pending I guess...

glen.grant Mon, 06/18/2007 - 03:34
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Its in nvram even though you can't see it like IOS . If you change to transparent and then have any thought about changing back be very careful about the vtp revision numbers , you could easily over write the existing vlan database you insert it back into the server client environment and the revision number is higher.

arnaud.chiaberge Mon, 06/18/2007 - 04:21
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Thanks Glen,


To summarize:


Since the vlan database is stored in nvram (even if I don't see it doing a "show run") all vlans definition would come back upon a reboot, even if in vpt client mode. right ?


Also, as I'm not planning to change back, and to focus on the change "client --> transparent", I can expect my vlan database not be lost in this operation. Also I should be able to hardcode vlans definition so that it appears in the "sh run" after that. right as well ?


Thanks

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