VTP Management

With  the VLAN Trunk Protocol (VTP) Management window, you can:

Note: Catalyst 2912MF, 2924M, and 3500 XL switches support 250 VLANs; all other Catalyst 2900, 1900, and 2820 switches support 64 VLANs. If you define more than the maximum number of VLANs or if the switch receives an advertisement that contains more than the maximum number of  VLANs, the switch automatically enters VTP transparent mode and operates with the VLAN configuration preceding the one that sent it into transparent mode. The count of 250 (64) VLANs always includes VLAN 1 but never includes VLANs 1002 to 1005; the switch supports 250 (64) active VLANs, plus VLANs 1002 through 1005, which are reserved.

Viewing VTP Information

The VTP protocol maintains VLAN configuration consistency throughout the network by distributing VLAN information to the network. VLAN information is sent to network devices in advertisements that contain the VTP management domain name, the current configuration revision number, the VLANs that the server knows about, and certain VLAN parameters. Any time you change a VLAN, VTP automatically sends an advertisement to update all other network devices.

To display current VTP information, click the VTP Information tab. This is a read-only tab.

Configuring VTP

Before you create a VLAN, you must decide whether to use VTP in your network. If you plan to use VTP, you must decide whether the switch will be a VTP server or VTP client and whether to enable VTP version 2 mode. If you do not use VTP, you must set the switch to transparent mode.

Note: If you are upgrading your switch from a software version that supports VLANs but not VTP, and if the saved configuration file has ports assigned to a VLAN other than VLAN 1, VTP enters transparent mode, and the domain name shown on the VTP Configuration page is UPGRADE. VTP learns about the previous VLAN configurations but does not globally propagate them. If you want to use VTP, you must select Server from the VTP Mode Control drop-down list.

Review the VLAN configuration rules before starting this procedure.

To configure VTP:

  1. Select the VTP Configuration tab from the VTP Management window.
  2. From the VTP V2 Mode drop-down list, select Enabled to enable version 2.
    By default, Disabled is selected, which means that version 1 mode is selected.
    Each VTP switch automatically detects the capabilities of all the other VTP devices. All VTP switches in the network must support version 2 mode; otherwise, you must configure them to operate with VTP version 1.
    Note: If you are using VTP in a Token Ring environment or configuring a TRBRF or TRCRF VLAN media type, you must set VTP V2 Mode to Enabled. If you are configuring a Token Ring or Token Ring-NET VLAN media type, you must disable VTP V2 mode.
  3. From the VTP Mode Control drop-down list, select Server, Client, or Transparent.
    The default is Server.
    Before you set this option, review the VTP mode control field descriptions.
    If you select Client, you cannot add, modify, or remove VLAN configurations.
    Note: You must select Server if Domain Name contains UPGRADE.
  4. From the VTP Pruning Mode drop-down list, select Enabled.
    By default, pruning is disabled. When enabled, global pruning occurs for the entire management domain. Pruning restricts flooded traffic to trunk links that the traffic must use to access ports where the traffic is required.
    Note: You can specify the VLANs where pruning is done by using the pruning eligibility list (select VLAN > VLAN Membership from the menu bar, and then select the Trunk Configuration tab).
  5. In the Domain Name field, enter a name that identifies the administrative domain for the switch.
    Note: Do not configure a domain name if all switches are operating as VTP clients; in this case, configuring a domain name makes changing the VLAN configuration for the domain impossible.
    By default, no domain name is defined, but VTP is not active until a name is defined or until it is learned from an advertisement.
    Domain names range from 1 to 32 characters and are case sensitive.
    Note: Once the domain name is configured or learned, you cannot reset it to a blank or undefined name.
    If you are configuring the switch for VMPS, make sure this domain name matches the one in the VMPS configuration file.
  6. In the VTP Password field, enter a password (optional).
    Passwords range from 8 to 64 characters and are case sensitive. By default, no password is defined.
    If you assign a VTP password, it must match the password for the VTP domain of the switch. This password is required for authentication when VTP advertisement reach the switch.
    Note: Catalyst 2900 or 3500 XL switch that boot without the correct VTP password reject VTP advertisements until this password is assigned. If you add a switch to a network that uses VTP, the switch learns the VTP domain name after the domain password is assigned.
  7. Click OK to put your changes in effect an close the VTP Management window.

Adding a New Ethernet VLAN

This switch supports only Ethernet interfaces. However, you can use the VTP Management window to configure media-specific characteristics for VLAN Trunk Protocol (VTP) global advertisements to other switches (see Adding a New Non-Ethernet VLAN).

Note: You cannot add a new VLAN configuration if you set the VTP Control Mode to Client (see Configuring VTP).

To add a new Ethernet VLAN:

  1. Select the VLAN Configuration tab from the VTP Management window.
  2. Click New to display the VLAN Configuration - New VLAN dialog box.
    By default, this dialog box contains configuration parameters for Ethernet VLANs.
  3. See this help file for configuration instructions:
    Configuring Ethernet-Specific VLAN Characteristics

Adding a New Non-Ethernet VLAN

This switch supports only Ethernet interfaces. However, you can use the VTP Management window to configure media-specific characteristics for VLAN Trunk Protocol (VTP) global advertisements to other switches.

Note: You cannot add a new VLAN configuration if you set the VTP Control Mode to Client (see Configuring VTP).

To add a new non-Ethernet VLAN:

  1. Select the VLAN Configuration tab from the VTP Management window.
  2. Click New to display the VLAN Configuration - New VLAN dialog box.
    By default, is dialog box contains configuration parameters for Ethernet VLANs.
  3. To configure a different media type, select the media from the VLAN Media Type drop-down list.
    A new VLAN Configuration dialog box is displayed that contains configuration parameters for the media type that you selected.
  4. See one of these help files for media-specific configuration instructions:
    Configuring FDDI VLAN Characteristics
    Configuring FDDI-NET VLAN Characteristics
    Configuring Token Ring VLAN Characteristics
    Configuring Token Ring-NET VLAN Characteristics

Modifying a VLAN Configuration

Use the VLAN Configuration tab to modify a VLAN. You cannot modify a VLAN configuration if you set the VTP Control Mode to Client (see Configuring VTP).

To modify a VLAN:

  1. Select the VLAN Configuration tab from the VTP Management window.
  2. Select the VLAN that you want to change.
    This displays the VLAN Configuration - Modify dialog box.
  3. Click Modify to display the VLAN Configuration - Modify dialog box.
    This dialog box contains the configuration parameters for the media type that you selected.
  4. Make the necessary changes.
    Click the Help button on the VLAN Configuration - Modify dialog box for instructions on completing this procedure.

Removing a VLAN Configuration

Use the VLAN Configuration tab to remove a VLAN. You cannot remove a VLAN configuration if you set the VTP Control Mode to Client.

To remove a VLAN configuration:

  1. Select the VLAN Configuration tab from the VLAN Management window.
  2. Select the VLAN that you want to remove from the table on this tab.
  3. Click Remove.
    The VLAN is no longer displayed on the VLAN Configuration tab.
  4. Click OK to save your changes to nonvolatile memory and close this window.

VTP Mode Control Field Descriptions

The VTP mode control determines how a switch interacts with the VTP database.

Field Description
Server A switch in VTP server mode is enabled for VTP and sends advertisements. You can configure VLANs on it. The switch can recover all the VLAN information in the current VTP database from nonvolatile storage after reboot. By default, every switch is a VTP server, which is the recommended mode of operation.
Client A switch in VTP client mode is enabled for VTP and can send advertisements, but it does not have enough nonvolatile storage to store VLAN configurations. You cannot configure VLANs on it. When a VTP client starts up, it does not transmit VTP advertisements until it receives advertisements to initialize its VLAN database.
Transparent A switch in VTP transparent mode is locally disabled for VTP, but it does not transmit advertisements or learn from advertisements sent by other devices, and it cannot affect VLAN configurations on other devices in the network. The switch receives VTP advertisements and forwards them on all trunk ports except the one on which the advertisement was received.