Vtp Overview - Cisco Nexus 9000 Series Configuration Manual

VTP Overview

those VLAN changes affect only the local device. A VTP transparent network device does not advertise its
VLAN configuration and does not synchronize its VLAN configuration based on received advertisements.
VLAN 1 is required on all trunk ports used for switch interconnects if VTP is supported in the network.
Note
Disabling VLAN 1 from any of these ports prevents VTP from functioning properly.
VTP Overview
VTP allows each router or LAN device to transmit advertisements in frames on its trunk ports. These frames
are sent to a multicast address where they can be received by all neighboring devices. They are not forwarded
by normal bridging procedures. An advertisement lists the sending device's VTP management domain, its
configuration revision number, the VLANs which it knows about, and certain parameters for each known
VLAN. By hearing these advertisements, all devices in the same management domain learn about any new
VLANs that are configured in the transmitting device. This process allows you to create and configure a new
VLAN only on one device in the management domain, and then that information is automatically learned by
all the other devices in the same management domain.
Once a device learns about a VLAN, the device receives all frames on that VLAN from any trunk port by
default, and if appropriate, forwards them to each of its other trunk ports, if any. This process prevents
unnecessary VLAN traffic from being sent to a device.
VTP also publishes information about the domain and the mode in a shared local database that can be read
by other processes such as Cisco Discovery Protocol (CDP).
VTP Modes
VTP is supported in these modes:
• Transparent—Allows you to relay all VTP protocol packets that it receives on a trunk port to all other
If VTP is in transparent mode, you can configure VLAN long names of up to 128 characters.
VTP Per Interface
VTP allows you to enable or disable the VTP protocol on a per-port basis to control the VTP traffic. When a
trunk is connected to a switch or end device, it drops incoming VTP packets and prevents VTP advertisements
on this particular trunk. By default, VTP is enabled on all the switch ports.
Guidelines and Limitations for Configuring VTP
VTP has the following configuration guidelines and limitations:
• show commands with the internal keyword are not supported.
Cisco Nexus 9000 Series NX-OS Layer 2 Switching Configuration Guide, Release 7.x
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trunk ports. When you create or modify a VLAN that is in VTP transparent mode, those VLAN changes
affect only the local device. A VTP transparent network device does not advertise its VLAN configuration
and does not synchronize its VLAN configuration based on received advertisements.
Configuring VTP