Cisco NM-8B-U - HW ROUTERS L-M User Manual page 6

Feature Overview
VTP Domain
A VTP domain (also called a VLAN management domain) is made up of one or more interconnected
switches that share the same VTP domain name. A switch can be configured to be in one and only one
VTP domain. You make global VLAN configuration changes for the domain using either the
command-line interface (CLI) or Simple Network Management Protocol (SNMP).
By default, the switch is in VTP server mode and is in an un-named domain state until the switch receives
an advertisement for a domain over a trunk link or until you configure a management domain. You cannot
create or modify VLANs on a VTP server until the management domain name is specified or learned.
If the switch receives a VTP advertisement over a trunk link, it inherits the management domain name
and the VTP configuration revision number. The switch ignores advertisements with a different
management domain name or an earlier configuration revision number.
If you configure the switch as VTP transparent, you can create and modify VLANs but the changes affect
only the individual switch.
When you make a change to the VLAN configuration on a VTP server, the change is propagated to all
switches in the VTP domain. VTP advertisements are transmitted out all trunk connections using IEEE
802.1Q encapsulation.
VTP maps VLANs dynamically across multiple LAN types with unique names and internal index
associations. Mapping eliminates excessive device administration required from network administrators.
VTP Modes
You can configure a switch to operate in any one of these VTP modes:
• Server-In VTP server mode, you can create, modify, and delete VLANs and specify other
configuration parameters (such as VTP version) for the entire VTP domain. VTP servers advertise
their VLAN configuration to other switches in the same VTP domain and synchronize their VLAN
configuration with other switches based on advertisements received over trunk links. VTP server is
the default mode.
• Client-VTP clients behave the same way as VTP servers, but you cannot create, change, or delete
VLANs on a VTP client.
• Transparent-VTP transparent switches do not participate in VTP. A VTP transparent switch does not
advertise its VLAN configuration and does not synchronize its VLAN configuration based on
received advertisements. However, in VTP version 2, transparent switches do forward VTP
advertisements that they receive out their trunk interfaces.
VTP Advertisements
Each switch in the VTP domain sends periodic advertisements out each trunk interface to a reserved
multicast address. VTP advertisements are received by neighboring switches, which update their VTP
and VLAN configurations as necessary.
The following global configuration information is distributed in VTP advertisements:
VLAN IDs (801.Q)
•
VTP domain name
•
• VTP configuration revision number
• VLAN configuration, including maximum transmission unit (MTU) size for each VLAN
• Frame format
Cisco IOS Release 12.2(2)XT, 12.2(8)T, and 12.2(15)ZJ
6
16- and 36-Port Ethernet Switch Module for Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series