Enabling and Configuring VLAN Trunking Protocol (VTP) on Cisco 1900 Switches

The VLAN Trunking Protocol (VTP) is used to manage the configuration of switches that are part of a VTP management domain, as we learned in Chapter 3. Recall that three VTP modes exist – server, client, and transparent mode. Once a VTP server is configured, any changes made (such as adding or removing VLANs) will be propagated throughout the VTP domain. Remember that all members of the same VTP management domain must be configured with the same VTP password.

Cisco1912#config t
Enter configuration commands, one per line. End with CNTL/Z
Cisco1912(config)#vtp ?
client VTP client
domain Set VTP domain name
password Set VTP password
pruning VTP pruning
server VTP server
transparent VTP transparent
trap VTP trap
Cisco1912(config)#vtp server
Cisco1912(config)#vtp domain ?
WORD Name of the VTP management domain
Cisco1912(config)#vtp domain 2000trainers.com
Cisco1912(config)#vtp password cisco999
Cisco1912#show vtp
VTP version: 1
Configuration revision: 1
Maximum VLANs supported locally: 1005
Number of existing VLANs: 6
VTP domain name : 2000trainers.com
VTP password : cisco999
VTP operating mode : Server
VTP pruning mode : Disabled
VTP traps generation : Enabled
Configuration last modified by: at 00-00-0000 00:00:00

VTP pruning was also discussed in Chapter 3. When VTP pruning is enabled, traffic will not be passed to another switch across a trunk link unless that switch has ports configured for a given VLAN. For example, imagine SwitchA has VLANs 1, 2, and 3 configured, and a trunk link to SwitchB. If VTP pruning is enabled, and SwitchB has no ports on VLAN 2, traffic for VLAN 2 will not passed to it. VLAN pruning is enabled using the command vtp pruning enable.

Cisco1912(config)#vtp pruning ?
disable Disable VTP pruning
enable Enable VTP pruning
Cisco1912(config)#vtp pruning enable

Recall from earlier in this appendix that while the command delete nvram erases the configuration of a switch, it does not delete the VTP database. To delete VTP information from a Cisco 1900 switch, you must issue the delete vtp command, which also requires the switch to reload.

Cisco1912#delete ?
nvram NVRAM configuration
vtp Reset VTP configuration to defaults
Cisco1912#delete vtp

This command resets the switch with VTP parameters set to factory defaults.
All other parameters will be unchanged.

Reset system with VTP parameters set to factory defaults, [Y]es or [N]o? Yes

Author: Dan DiNicolo

Dan DiNicolo is a freelance author, consultant, trainer, and the managing editor of 2000Trainers.com. He is the author of the CCNA Study Guide found on this site, as well as many books including the PC Magazine titles Windows XP Security Solutions and Windows Vista Security Solutions. Click here to contact Dan.