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VTP

Category:Cisco Systems -> Routing and Switching

Will VLANs 500 and 600 be moved from Switch B to Switch A according to the following diagram?

VTP-10.jpg

Yes, they will.

Here’s a little test.

The initial conditions for Switch A (trunk link to Switch B unplugged):

Switch A#sh vtp st
VTP Version                     2
Configuration Revision          
1
Maximum VLANs supported locally 
255
Number of existing VLANs        
10
VTP Operating Mode              
Server
VTP Domain Name                 
NULL
VTP Pruning Mode                
Disabled
VTP V2 Mode                     
Disabled
VTP Traps Generation            
Disabled
MD5 digest                      
0xDE 0x74 0x9A 0x72 0x4B 0x20 0x27 0xE1 
Configuration last modified by 192.168.0.1 at 3
-1-93 00:31:39
Local updater ID is 0.0.0.0 
(no valid interface found)

Switch 
A#sh vl

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1Fa0/2Fa0/4Fa0/5
                                                Fa0
/6Fa0/9Fa0/11Fa0/12
                                                Fa0
/13Fa0/15Fa0/16Fa0/17
                                                Fa0
/18Fa0/19Fa0/20Fa0/21
                                                Fa0
/22Fa0/23Fa0/24Gig1/1
                                                Gig1
/2
100  VLAN0100                         active    Fa0
/10
120  VLAN0120                         active    Fa0
/3
155  VLAN0155                         active    Fa0
/14
200  VLAN0200                         active    Fa0
/7
300  VLAN0300                         active    Fa0
/8
1002 fddi
-default                     act/unsup 
1003 token
-ring-default               act/unsup 
1004 fddinet
-default                  act/unsup 
1005 trnet
-default                    act/unsup 

The initial conditions for Switch B (trunk link to Switch A unplugged):

Switch B(config)#do sh vl

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/1Fa0/3Fa0/4Fa0/5
                                                Fa0
/6Fa0/7Fa0/8Fa0/9
                                                Fa0
/10Fa0/11Fa0/12Fa0/13
                                                Fa0
/14Fa0/15Fa0/16Fa0/17
                                                Fa0
/18Fa0/19Fa0/20Fa0/21
                                                Fa0
/22Fa0/23Fa0/24Gig1/1
                                                Gig1
/2
100  VLAN0100                         active    
120  VLAN0120                         active    
155  VLAN0155                         active    
200  VLAN0200                         active    
300  VLAN0300                         active    
500  VLAN0500                         active    
600  VLAN0600                         active    
1002 fddi
-default                     act/unsup 
1003 token
-ring-default               act/unsup 
1004 fddinet
-default                  act/unsup 
1005 trnet
-default                    act/unsup 

Switch B(config)#do sh vtp st
VTP Version                     2
Configuration Revision          
3
Maximum VLANs supported locally 
255
Number of existing VLANs        
12
VTP Operating Mode              
Client
VTP Domain Name                 
NULL
VTP Pruning Mode                
Disabled
VTP V2 Mode                     
Disabled
VTP Traps Generation            
Disabled
MD5 digest                      
0x64 0x22 0xD7 0xB3 0x0F 0x95 0x38 0x5E 
Configuration last modified by 0.0.0.0 at 3
-1-93 00:04:04 

Now let’s physically connect both switches and see if the “server” Switch A with VTP revision 1 renewed its VLAN database from the client Switch B with greater VTP revision number which is 3:

Switch A#sh vl

VLAN Name                             Status    Ports
---- -------------------------------- --------- -------------------------------
1    default                          active    Fa0/2Fa0/4Fa0/5Fa0/6
                                                Fa0
/9Fa0/11Fa0/12Fa0/13
                                                Fa0
/15Fa0/16Fa0/17Fa0/18
                                                Fa0
/19Fa0/20Fa0/21Fa0/22
                                                Fa0
/23Fa0/24Gig1/1Gig1/2
100  VLAN0100                         active    Fa0
/10
120  VLAN0120                         active    Fa0
/3
155  VLAN0155                         active    Fa0
/14
200  VLAN0200                         active    Fa0
/7
300  VLAN0300                         active    Fa0
/8
500  VLAN0500                         active    
600  VLAN0600                         active    
1002 fddi
-default                     act/unsup 
1003 token
-ring-default               act/unsup 
1004 fddinet
-default                  act/unsup 
1005 trnet
-default                    act/unsup 

So VTP mode client does not necessarily mean that the switch will only import configuration from VTP server mode switch. Thus bringing a VTP client mode switch to the campus, make sure its revision number is lower than that of your production switches or it will corrupt your original VLAN database regardless that it’s only a VTP client switch.

By privilege15