The difference between VTP server and transparent mode on Catalyst Switch.

[mhiyoshi]

Hello 

I have a question about the difference between VTP server mode and VTP transparent mode on general catalyst switch.

Basically VTP server mode can create and modify VLAN configuration but  actually there is not any VLAN configuration through running-config, is it true?  When I checked it on Cat3550, certainly there is not VLAN configuration on VTP server mode. But VTP transparent can create VLAN and configuration but does not synchronize with other switch VLAN status. I appreciate any related information and reason of the VTP server mode specification, thank you very much.

##########################################################
[VTP Transparent mode]

3550#sh vtp status
VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 1005
Number of existing VLANs        : 27
VTP Operating Mode              : Transparent
VTP Domain Name                 :
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
*omit
3550#

3550#sh run
Building configuration...

*omit
!
vlan 99
 name TEST-VLAN

##########################################################

[VTP Server mode]

3550#sh vtp status
VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 1005
Number of existing VLANs        : 27
VTP Operating Mode              : Server
VTP Domain Name                 :
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
*omit
3550#

3550#sh run
Building configuration...

*no VLAN like above configuration on VTP transparent mode.

##########################################################

Best Regards,

Masanobu Hiyoshi

[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.

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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

VTP server (and client) mode maintain VLAN information in a VLAN database (vlan.dat [?] in flash), different from the config file.  This VLAN database is "shared" with adjacent switches.  All server and client switches in the same VTP domain will use the VLAN database with the highest revision number.  NB: both server and client mode dynamically share their database, but only server mode allows manual configuration changes.

VTP transparent mode, maintains its own VLAN definitions in its config file.  VTP transparent mode, though, can pass a VLAN database through it, although it doesn't use it itself.

[Karan Puri]

Hi mhiyoshi,

3550#sh vtp status
VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 1005
Number of existing VLANs        : 27
VTP Operating Mode              : Transparent
VTP Domain Name                 :
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
 

*omit
3550#

3550#sh run
Building configuration...

*omit
!
vlan 99
 name TEST-VLAN

The above out put indicates that Vlan is created and then mode changed to transparent. i.e why revision no is 0.

3550#sh vtp status
VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 1005
Number of existing VLANs        : 27
VTP Operating Mode              : Server
VTP Domain Name                 :
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
*omit
3550#

3550#sh run
Building configuration...

*no VLAN like above configuration on VTP transparent mode.

This indicates that vlan never created in server mode nor learnt from another switch as revision no is 0

[mhiyoshi]

Hello karanpuri88

I think if I modify VLAN setting the revision number has been changed in this example "0" to "1", but if the VTP mode has changed from server to transparent then the revision number has been reset like below.

3550(config)#no vlan 999
3550(config)#end
3550#sh vtp status
VTP Version                     : 2
Configuration Revision          : 1
Maximum VLANs supported locally : 1005
Number of existing VLANs        : 27
VTP Operating Mode              : Server
VTP Domain Name                 :
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
*omit
3550#
3550#conf t
3550(config)#vtp mode transparent
Setting device to VTP TRANSPARENT mode.
3550(config)#end
3550#
3550#sh vtp st
3550#sh vtp status
VTP Version                     : 2
Configuration Revision          : 0
Maximum VLANs supported locally : 1005
Number of existing VLANs        : 27
VTP Operating Mode              : Transparent
VTP Domain Name                 :
VTP Pruning Mode                : Disabled
VTP V2 Mode                     : Disabled
VTP Traps Generation            : Disabled
*omit
 

[Karan Puri]

Yes you are correct you can create the vlan in server mode and then change the mode to transparent. Then later dont be confuse by seeing how vlan is there in configuration where vtp is in transparent mode.

[Joseph W. Doherty]

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

Setting mode to transparent, revision number is reset and is not incremented.

Server/client mode use revision number to "know" which switch has the "newer" VLAN database.  Highest revision number replaces any with lower revision numbers.

[Karan Puri]

Yes i told the same thing in above post.