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VLAN database

wilburt44
Level 1
Level 1

I've used 3750 switches for a long time and the L2 vlan info has always been in vlan.dat. Now it is in the running config. see a portion below.

Why is it in the running config now? It is a Catalyst 3750g-ts-s IOS version 12.2(50)SE5, RELEASE SOFTWARE (fc1)

spanning-tree extend system-id

!

vlan internal allocation policy ascending

!

vlan 2

name Core

!

vlan 5

name FTTH

!

vlan 30

name M_BoE

!

vlan 40

name SE

!        

vlan 100

!

!

!

interface GigabitEthernet1/0/1

!

1 Accepted Solution

Accepted Solutions

Jon Marshall
Hall of Fame
Hall of Fame

It should be because your switch is running in VTP transparent mode. When the switch runs in VTP transparent mode the vlans are written to the running-config as opposed to when running in VTP server/client mode where the vlan info is stored in the vlan.dat file.

Do a "sh vtp status" and you should see the switch is running VTP transparent mode.

Jon

View solution in original post

2 Replies 2

Jon Marshall
Hall of Fame
Hall of Fame

It should be because your switch is running in VTP transparent mode. When the switch runs in VTP transparent mode the vlans are written to the running-config as opposed to when running in VTP server/client mode where the vlan info is stored in the vlan.dat file.

Do a "sh vtp status" and you should see the switch is running VTP transparent mode.

Jon

Friends,

In fact, the VTP Transparent mode is a bit curious: the VLANs are stored both in vlan.dat and in the running-config. If by some accident, the stored running-config becomes desynchronized from the vlan.dat file (for example, the vlan.dat file is copied to the FLASH from a backup and it differs from the data in the startup-config), the vlan.dat has precedence when the switch boots the next time.

Best regards,

Peter

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