About The Vlan Trunking Protocol; Guidelines And Limitations - Cisco Nexus 5000 Series Configuration Manual

About the VLAN Trunking Protocol

Newly created VLANs remain unused until ports are assigned to the specific VLAN. All the ports are assigned
to VLAN1 by default.
Depending on the range of the VLAN, you can configure the following parameters for VLANs (except the
default VLAN):
• VLAN name
• Shutdown or not shutdown
When you delete a specified VLAN, the ports associated to that VLAN are shut down and no traffic flows.
However, the system retains all the VLAN-to-port mapping for that VLAN, and when you reenable, or recreate,
the specified VLAN, the system automatically reinstates all the original ports to that VLAN.
Commands entered in the VLAN configuration submode are immediately executed.
Note
VLANs 3968 to 4047 and 4094 are reserved for internal use; these VLANs cannot be changed or used.
About the VLAN Trunking Protocol
VTP is a distributed VLAN database management protocol that synchronizes the VTP VLAN database across
domains. A VTP domain includes one or more network switches that share the same VTP domain name and
that are connected with trunk interfaces. Each switch can be in only one VTP domain. Layer 2 trunk interfaces,
Layer 2 port channels, and virtual port channels (vPCs) support VTP functionality. Cisco NX-OS Release
5.0(2)N1(1) introduces the support for VTPv1 and VTP2. Beginning in Cisco NX-OS Release 5.0(2)N2(1),
you can configure VTP in client or server mode. Prior to NX-OS Release 5.0(2)N2(1), VTP worked only in
transparent mode.
There are four VTP modes:
• Server mode–Allows users to perform configurations, it manages the VLAN database version #, and
• Client mode–Does not allow user configurations and relies on other switches in the domain to provide
• Off mode—Allows you to access the VLAN database (VTP is enabled) but not participate in VTP.
• Transparent mode–Does not participate in VTP, uses local configuration, and relays VTP packets to

Guidelines and Limitations

VTP has the following configuration guidelines and limitations:
• When a switch is configured as a VTP client, you cannot create VLANs on the switch in the range of 1
• VLAN 1 is required on all trunk ports used for switch interconnects if VTP is supported in the network.
Cisco Nexus 5000 Series NX-OS Layer 2 Switching Configuration Guide, Release 5.0(3)N1(1)
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stores the VLAN database.
configuration information.
other forward ports. VLAN changes affect only the local switch. A VTP transparent network switch
does not advertise its VLAN configuration and does not synchronize its VLAN configuration based on
received advertisements.
to 1005.
Disabling VLAN 1 from any of these ports prevents VTP from functioning properly.
Configuring VLANs