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Software Configuration Guide—Release 15.0(2)SG
OL-23818-01
Chapter 13 Configuring VLANs, VTP, and VMPS
VLAN Trunking Protocol
• In a Token Ring environment, you must enable VTP version 2 or version 3 for Token Ring VLAN
switching to function properly.
• Two VPT version 3 regions can only communicate in transparent mode over a VTP version 1 or VTP
version 2 region.
• All network devices in a VTP domain must run the same VTP version.
• You must configure a password on each network device in the management domain when VTP is in
secure mode.
Caution If you configure VTP in secure mode and you do not assign a management domain password to each
network device in the domain, the management domain does not function properly.
• A VTP version 2-capable network device can operate in the same VTP domain as a network device
running VTP version 1 if VTP version 2 is disabled on the VTP version 2-capable network device
(VTP version 2 is disabled by default).
• Do not enable VTP version 2 on a network device unless all of the network devices in the same VTP
domain are version 2-capable. When you enable VTP version 2 on a server, all of the
version 2-capable network devices in the domain enable VTP version 2.
• Enabling or disabling VTP pruning on a VTP server enables or disables VTP pruning for the entire
management domain.
• Configuring VLANs as eligible for pruning on a Catalyst 4500 series switch affects pruning
eligibility for those VLANs on that switch only, not on all network devices in the VTP domain.
• The VLAN database is saved in the NVRAM file in a format compliant with the VTP version
running on the system. Since older images supporting only VTP version 2 do not recognize the VTP
version 3 file format, the NVRAM VLAN database information is lost if the system is downgraded
from a new image supporting VTP to one that does not.
VTP Default Configuration
Table 13-3 shows the default VTP configuration.
The default VTP mode for newly manufactured Catalyst 4500 supervisor engines, Catalyst 4900 series
switches, and the Cisco ME 4924-10GE switch is transparent. Deleting vlan.dat or entering the
erase cat4000_flash: command, and resetting the switch changes the VTP mode to server.
Table 13-3 VTP Default Configuration
Feature Default Value
VTP domain name Null
VTP mode Server
VTP version 2 enable state Version 2 is disabled
VTP password None
VTP pruning Disabled
