Cisco Catalyst 3560-X User Manual

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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-25303-03
Chapter 1 Configuring VTP
Understanding VTP
VTP Advertisements
Each switch in the VTP domain sends periodic global configuration advertisements from each trunk port
to a reserved multicast address. Neighboring switches receive these advertisements and update their VTP
and VLAN configurations as necessary.
Note Because trunk ports send and receive VTP advertisements, you must ensure that at least one trunk port
is configured on the switch or switch stack and that this trunk port is connected to the trunk port of
another switch. Otherwise, the switch cannot receive any VTP advertisements. For more information on
trunk ports, see the “Configuring VLAN Trunks” section on page 1-14.
VTP advertisements distribute this global domain information:
• VTP domain name
• VTP configuration revision number
• Update identity and update timestamp
• MD5 digest VLAN configuration, including maximum transmission unit (MTU) size for each
VLAN.
• Frame format
VTP advertisements distribute this VLAN information for each configured VLAN:
• VLAN IDs (ISL and IEEE 802.1Q)
• VLAN name
VTP 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 or version 3, transparent switches do forward VTP advertisements that they
receive from other switches through their trunk interfaces. You can create, modify, and delete VLANs on
a switch in VTP transparent mode.
In VTP versions 1 and 2, the switch must be in VTP transparent mode when you create extended-range
VLANs. VTP version 3 also supports creating extended-range VLANs in client or server mode. See the
“Configuring Extended-Range VLANs” section on page 1-10.
In VTP versions 1 and 2, the switch must be in VTP transparent mode when you create private VLANs and
when they are configured, you should not change the VTP mode from transparent to client or server mode.
VTP version 3 also supports private VLANs in client and server modes. See Chapter 1, “Configuring
Private VLANs.” When private VLANs are configured, do not change the VTP mode from transparent to
client or server mode.
When the switch is in VTP transparent mode, the VTP and VLAN configurations are saved in NVRAM,
but they are not advertised to other switches. In this mode, VTP mode and domain name are saved in the
switch running configuration, and you can save this information in the switch startup configuration file by
using the copy running-config startup-config privileged EXEC command. In a switch stack, the running
configuration and the saved configuration are the same for all switches in a stack.
VTP off A switch in VTP off mode functions in the same manner as a VTP transparent switch, except that it does
not forward VTP advertisements on trunks.
Table 1-1 VTP Modes (continued)
VTP Mode Description

Cisco Catalyst 3560-X Specifications

General

Brand	Cisco
Model	Catalyst 3560-X
Category	Network Router
Language	English