VTP Domain to VTP Transparent mode

[david.klein]

I have a number of stacked switches at our corporation which are in VTP Server/Client mode, and I would like to change them back to VTP Transparent mode, but  want to verify that switching to VTP transparent mode, will not affect the current configuration on the switch.  I have heard VTP Domain is not the way to go, and I would hate for a switch to be put on network somewhere, and end up wiping out the other switches because it had a lower mac.

One other question I have is this.  If you have say a stack of 2 switches using flex cables, can you copy the config of individual switches in the stack to a tftp?  Also I want to add another switch to this stack.   I know I need the same IOS on all switches, but will the switches all reboot when I unplug the flexstack cable and plug new switch in?  In a vtp environment the mac is the first factor that is looked at for who is the server vs client in VTP Domain?

[Rashid Thompson]

Personally I think VTP is the way to go depending on the scalability of your network and how secure your network is.  To answer your questions, changing the mode from server/client to transparent will not affect any current configs. You can copy a single switch config to a stacked switch but please be aware of the amount of interfaces, features, and IOS that both switches have. I would make sure the config can work on both switches. Now if you want to add a switch to the stack, unplugging the flex cable will not affect anything. In a VTP environment, the VTP domain is the first factor looked at.  Hope this helps

[Collin Clark]

When migrating from Client/Server to Transparent the VLAN's will remain on the switch. On stacks, the config is already copied to each switch. This is case there is a Master switch failure, another switch can take over and have the correct config. You don't need to back up every switch individually. Officially you're supposed to power down the stack, unplug the stack cables, cable in the new switch, then power up. However many people (including me) have installed a new switch without the power down and not had any problems. VTP looks at the configuration number on the switch not the MAC address. You're thinking of the Stack Master Election which looks at the MAC.

[david.klein]

How do I find the configuration number, and can you change this configuration number so when you add a switch it does not end up becoming the server switch and wiping out the other switches if you would need to?

[Joseph W. Doherty · Accepted solution]

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The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

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Posting

You should be able to "see" the VTP VLAN database revision number by doing a show VTP command.

Before adding a VTP switch to your network, set VTP mode to transparent.  When it's on the network, set VTP mode to server or client.  This will reset the database revision number to zero (or one? - forget which).  If other VTP conditions are then correct, new switch should acquire current VLAN database.

[david.klein]

So would I be able to just setup a new switch in the vtp domain.  Make it a client, then plug it into the stack instead for makeing it vtp transparent first?

[Joseph W. Doherty · Accepted solution]

Disclaimer

The  Author of this posting offers the information contained within this  posting without consideration and with the reader's understanding that  there's no implied or expressed suitability or fitness for any purpose.  Information provided is for informational purposes only and should not  be construed as rendering professional advice of any kind. Usage of this  posting's information is solely at reader's own risk.

Liability Disclaimer

In  no event shall Author be liable for any damages whatsoever (including,  without limitation, damages for loss of use, data or profit) arising out  of the use or inability to use the posting's information even if Author  has been advised of the possibility of such damage.

Posting

You should be able to change VTP mode from server or client to transparent without any adverse impact.

I have heard VTP Domain is not the way to go, and I would hate for a switch to be put on network somewhere, and end up wiping out the other switches because it had a lower mac.

Personally, I like VTP, and v3 can avoid the usual "accidental" VLAN database overwrite.  BTW, it's not so much lower MAC you need to be concerned about, but a VTP server or client with a lower VTP database revision for the same VTP domain.

One other question I have is this.  If you have say a stack of 2 switches using flex cables, can you copy the config of individual switches in the stack to a tftp?  Also I want to add another switch to this stack.   I know I need the same IOS on all switches, but will the switches all reboot when I unplug the flexstack cable and plug new switch in?  In a vtp environment the mac is the first factor that is looked at for who is the server vs client in VTP Domain?

Unclear about your question about a stack of 2.  If you're thinking like a 3750 kind of stack, there's only only configuration for all the devices in the stack.  If you're thinking of cascaded physical switches, each running its own config, sure you can copy each of those.

Again, if you're asking about a 3750 type stack, you can add a switch to an existing stack.  (Believe that's also true for 3850 and 2960S type stacks too.)

For VTP (at least for v1 and v2), any VTP server or client will "share" its VLAN database via VTP.  What they compare is VTP domain and database revision number.  Highest database revision number, for the VTP domain, is considered the "best" for VLAN definitions.

BTW, it's possible you can have multiple VTP devices, with same domain and database revision, with different VLAN information (at lease with v1 and v2).  This might happen if you allow more than one device to be a VTP server and multiple VTP devices are manually changed with different VLAN information at the same time.  (So, to avoid, don't have more than one VTP server.)