Vtp Version 3 Modes - Cisco WS-C2948G-GE-TX Configuration Manual

Understanding How VTP Version 3 Works

VTP Version 3 Modes

The default mode for VTP is version 1, server mode. The off mode can be exited only after you configure
a VTP domain name on the switch. The "domain discovery" that is used in VTP version 1 and VTP
version 2 is not available in VTP version 3.
Switches running VTP version 3 have the following common characteristics:
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VTP version 3 modes are described in these sections:
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For more information, see the
Client Mode
VTP version 3 clients are similar to VTP version 1 and VTP version 2 clients, as follows:
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Server Mode
Primary and secondary servers are two types of servers that may exist on an instance in the VTP domain.
Secondary Server
When a switch is configured to be a server, it becomes a secondary server by default. As a secondary
server, a VTP version 3 switch behaves as a client with the following exceptions:
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Catalyst 4500 Series, Catalyst 2948G, Catalyst 2948G-GE-TX, and Catalyst 2980G Switches Software Configuration Guide—Release 8.2GLX
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They accept VTP packets only from the same VTP domain.
If they do not have a primary server, they accept the primary server that is associated with the first
VTP database that they receive for any instance.
They accept only a database with a higher revision number from their current primary server.
If they have a password configured (whether hidden or not hidden), they accept only a new database
or a takeover message if it contains the correct password.
Client Mode, page 9-18
Server Mode, page 9-18
Transparent and VTP Off Modes, page 9-19
A VTP client accepts a VTP configuration from the network but cannot generate or alter the
configuration.
A VTP client stores the VTP configuration that it receives in RAM (not NVRAM). When a VTP
client boots, it needs to reacquire the entire configuration that is propagated by VTP, including the
identity of the primary server.
A VTP client that cannot store the entire VTP configuration that is received in an instance to RAM,
immediately transitions to transparent mode.
A secondary server immediately stores the information that is received through VTP version 3 in
NVRAM. This NVRAM is part of the running configuration or startup configuration.
At startup, a secondary server that has a configuration in NVRAM starts advertising the
configuration. The main purpose of a VTP secondary server is to back up the configuration that is
propagated over the network.
Similar to a client, a VTP secondary server cannot modify the VTP configuration.
"Changing VTP Version 3 Modes" section on page
Chapter 9 Configuring VTP
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