VLAN Trunking Protocol (VTP)

ccnp-switching
Notes on VTP server, client, and transparent modes, revision numbers, VTP pruning, and configuration steps for versions 1, 2, and 3.
Published

Nov 22, 2017

VTP Pruning

By enabling VTP pruning, if there is no active VLAN in a switch (meaning that there is no member interface in a particular VLAN, so there is no traffic), VTP prevents that VLAN traffic from passing over a trunk

Enable VTP pruning by vtp pruning command on the VTP server

SW1#show vtp status
VTP Version capable             : 1 to 3
VTP version running             : 1
VTP Domain Name                 : hossein
VTP Pruning Mode                : Enabled
VTP Traps Generation            : Disabled
Device ID                       : 008d.72e3.9300
Configuration last modified by 0.0.0.0 at 11-22-17 16:06:10
Local updater ID is 0.0.0.0 (no valid interface found)

Feature VLAN:
--------------
VTP Operating Mode                : Server
Maximum VLANs supported locally   : 1005
Number of existing VLANs          : 15
Configuration Revision            : 13
MD5 digest                        : 0x10 0x9E 0xA5 0xD4 0xE7 0x04 0x46 0xA2 
                                    0x2D 0x76 0x20 0x20 0x93 0x78 0xDA 0xFB 

SW1#SW1#show interfaces pruning 

Port                Vlans pruned for lack of request by neighbor
Gi0/0               none
Gi0/1               10,20,30,40,50,60,70,80,100,110

Port                Vlan traffic requested of neighbor
Gi0/0               1
Gi0/1               1,10,20,30,40,50,60,70,80,100,110

VTP version 1 and 2 can prune VLAN IDs 2-1001

Note:

  • show interfaces trunk displays manually pruned VLANs
    • in interface level:
      • switchport trunk allowed vlan except 200
      • switchport trunk allowed vlan remove 200
  • show interfaces pruning displays VLANs pruned by VTP

VTP Version 1 and 2 Configuration

  1. Links between the switches must be trunked
  2. Define a domain name on the VTP Server: SW1(config)#vtp domain cisco
  3. Set a password on the VTP Server: SW1(config)#vtp password 123
  4. Define VTP mode client on the client switches: Client_1(config)#vtp mode client
  5. Set the password on the VTP Clients the same as in the VTP Server: Client_1(config)#vtp password 123
  • No need to define VTP domain on clients

VTP Version 3

  • Supports Private VLANs
  • Supports extended VLANs 1006-4094
    • Extended VLANs are NOT stored in flash:vlan.dat. They are stored in the running configuration
  • In VTP version 1 and 2 multiple servers are allowed. In VTP version 3 we have only one primary server.
SW1(config)#vtp domain cisco
Changing VTP domain name from NULL to cisco
SW1(config)#vtp version 3
SW1(config)#vtp password test
Setting device VTP password to test
SW1(config)#vlan 2017
VTP VLAN configuration not allowed when device is not the primary server for vlan database.
SW1(config)#end
SW1#vtp primary 
This system is becoming primary server for feature vlan 
No conflicting VTP3 devices found.
Do you want to continue? [confirm]
SW1#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
SW1(config)#vlan 2017
SW1(config-vlan)#exit

SW1#show vtp status
VTP Version capable             : 1 to 3
VTP version running             : 3
VTP Domain Name                 : cisco
VTP Pruning Mode                : Disabled
VTP Traps Generation            : Disabled
Device ID                       : 0030.2cb5.1600

Feature VLAN:
--------------
VTP Operating Mode                : Primary Server
Number of existing VLANs          : 5
Number of existing extended VLANs : 1
Maximum VLANs supported locally   : 4096
Configuration Revision            : 1
Primary ID                        : 0030.2cb5.1600
Primary Description               : SW1
MD5 digest                        : 0x16 0x5A 0xC5 0x6D 0xB8 0x29 0x72 0x12 
                                    0x6D 0xA3 0x01 0xC4 0xAE 0x38 0xAB 0x8C 


Feature MST:
--------------
VTP Operating Mode                : Transparent
          

Feature UNKNOWN:
--------------
VTP Operating Mode                : Transparent
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