Using VLAN and Bridge  [Support] (2024)

Table Of Contents

VLAN and Bridge

Procedures

Local Management Domain

Create VLAN

Delete VLAN

Modify VLAN

Using VLAN & Bridge

The VLAN & Bridge application allows you to configure groups of ports independent of their physical location as a virtual LAN. This arrangement is called a logical grouping the logical group is called a virtual LAN (VLAN). Ports or groups of ports in a VLAN are called VLAN members. VLANs prevent traffic, including broadcasts and multicasts, from being propagated to members of other VLANs.

Switches are interconnected by the Inter-Switch Link (ISL) port so that VLAN traffic can cross multiple switches. A Layer-2 switch is basically a bridge. Both switches and bridges allow multiple ports to be active simultaneously.

Every VLAN has an equivalent bridge. Most of the configuration required for bridging is related to the spanning-tree algorithm, which allows the connected network topology to contain multiple physical paths between two stations but constrains the active topology to a single-span tree. If a port on one bridge fails, the other bridges can reconfigure the topology and switch traffic to new paths. A VLAN, therefore, can be considered equivalent to a bridged LAN.

NoteIf the spanning-tree algorithm is not enabled, no backup path exists to maintain bridge connectivity.

To start the VLAN & Bridge application from CiscoView, select Configure>device>VLAN & Bridge.

VLAN and Bridge

The main window for VLAN and bridging configuration is the VLAN & Bridge window. The VLAN & Bridge window contains information about the currently configured VLANs in the device.

Timesaver

You can drag-and drop a port directly into a VLAN. Click on the port in the device display, drag it onto the opened VLAN & Bridge Table, then drop in into one of the VLAN fields. The system automatically assigns the port to the designated VLAN.

Hints for Configuring VLAN and Bridge Information for the Device.

VLANs can be of 5 types: Ethernet, FDDI, Token Ring, FDDI Net, and TRNet.

Use the action buttons in the VLAN & Bridge window as follows:

•The View Ports section contains the following action buttons:

•VLAN Members—Highlights in red the ports on the switch that belong to the selected VLAN.

•Inter Switch—Highlights in blue the ports on the switch that are running in ISL mode. To highlight the ports in a VLAN that are running in ISL mode in blue, select a VLAN, and click Inter Switch.

•Clear Ports—Clears the highlights in the device display. To clear the highlights in the device display, click Clear Ports.

•VLAN Non-Trunk Members—Displays a summary of ports that are non-trunk members of a selected VLAN.

•The Bridges section contains the following action buttons:

NoteThe buttons in the Bridges section depend on whether you select a TrVlan or a TrNetVlan entry from the VLAN table:
— If you select a TrVLAN entry, only Configure... and Forwarding... are displayed.
— If you select a TrNet VLAN entry, only Configure... is displayed.

•Configure... —Opens the Configure Bridge window and displays Bridge MIB variable information. See "VLAN Bridge Configuration" for more information.

•Forwarding... —Displays the bridge forwarding information for the selected device. See "Bridge Forwarding" for more information.

•Static... —Displays manually configured forwarding information about the bridge; this information is displayed in table form. See "Bridging Statics (Applicable to TR Ports only)" for more information.

•The VTP-VLAN section contains the following action buttons:

•Local Mgmt Domain—Displays the VTP Local Management Domain window. This is the domain from which all VLANs on the module can communicate with each other and with other ports on other Catalyst 5000 series modules. See "Local Management Domain" for more information.

•Create VLAN...—Displays the Create VLAN window. See "Create VLAN" for more information.

•Delete VLAN...—Deletes the selected VLAN. See "Delete VLAN" for more information.

•Modify VLAN...—Opens the Modify VLAN window. See "Modify VLAN" for more information.

Procedures

This section contains procedures for using the VTP-VLAN section tools.

Local Management Domain

The Local Management Domain window allows you to create a new VTP management domain and define the boundary of a defined VLAN or to modify or display the existing domain information.

NoteYou must provide a domain name to each VLAN to ensure the VLAN functions properly.

To create, modify, or display a management domain, perform the following steps:

Step1From the VLAN & Bridge, click Local Mgmt Domain. The VTP management Domain window opens.

Step2Enter information into (or review values in) the following fields:

NoteA domain name must be entered. If a domain name is not specified, ports cannot be assigned to any VLAN, regardless of the access level.

•Domain Index.

•Domain Name.

•Domain Local Mode (select either VTP client mode, VTP server mode, or transparent mode). Transparent mode is a non-client-server mode.

NoteThe Domain Local Mode must be set to server mode to create, modify, or delete a VLAN. When selected, server mode sets the switch to act as a server from which other servers will receive VLAN information.

•Domain Config Revision Number. This number is used for synchronization.

•Domain last Updater's IP. For example, this number is the server's IP address when VTP server mode is selected.

•Domain lastChange. This entry should display a date.

•Domain PruningState: Select either the enabled or disabled state.

Step3Click Modify to save the input and refresh the VLAN & Bridge window. If the device returns any errors during this operation, CiscoView displays the information.

Step4Repeat Steps 1 through 3 for each domain as required.

Step5Click Cancel to exit the window.

Create VLAN

The Create VLAN window allows you to create a new VLAN.

For additional information regarding the fields within the windows, click Help to access the online help.

To create a VLAN, perform the following steps:

Step1From the VLAN & Bridge table, click Create VLAN. The Create VLAN dialog box opens.

NoteAlthough all the fields are shown in the dialog box, any field not appropriate for the VLAN type is grayed out.

Step2Enter values into the following fields:

•VLAN Number. For VLANs of Ethernet type, enter any existing VLAN number from the preceding VLAN & Bridge table. For VLANs of (Token Ring) trCrf type, use a number that is not already assigned from the preceding VLAN & Bridge table.

•VLAN State (operational is the default setting; the other option is suspended).

VLAN Type (default is ethernet; other options are fddi, trcrf, fddiNet, or trbrf.)

For VLANs of type trBrf, you must create a net first, then use the Create VLAN window and select VLAN Type trCrf to create Token Ring VLANs inside the net. See Note below for more information.

NoteThe trCrf VLAN type is used for Token Ring VLANs made up of (at most) one transparently bridged LAN segment. The trbrf type is used for VLANs that represent the scope of many trCrf VLANs connected via a source routing bridge. The Token Ring trBrf type can be said to represent the bridged broadcast domain.

Step3Enter values into the following optional fields or leave the fields blank:

•VLAN Name. Enter any name, if desired. This name is used as the ELAN name for the ATM LAN Emulation segment of this VLAN.

•VLAN MTU Size. The range is 1500 through 18190 for all VLAN types. The MTU size is defined as the largest MAC-layer of the data frame that can be transmitted on the VLAN. For Token Ring VLANs, the default is 1500.

•VLAN SAID Field (Integer). This is the value of the 802.10 SAID field for the VLAN. For VLANs of Ethernet type, enter a unique number; no range is established but enter a number starting with 100,000 plus (+) the VLAN number, for example, 100015. This field is disabled for other VLAN types. This field is disabled for Token Ring VLANs.

•VLAN Ring Number. The range is 0x1 through 0xfff. This field is available for VLANs of type FDDI or Token Ring. Note: Source Routing (srb) must be configured for use on this VLAN. For Token Ring VLANs, use the Token Ring number here; or give any number within the sepcified range that is not duplicated in any other VLAN.

•VLAN Bridge Number. This is the bridge number of theVTP-capable switches for this VLAN. This field is disabled for VLANs of Ethernet and Token Ring types but enabled for VLAN types. This object is available only for VLANs that are involved with emulating token ring segments.

•VLAN STP Type. The type of the spanning-tree-protocol running on this VLAN. This field is disabled for VLANs of Ethernet and Token Ring types, but enabled for VLAN types.

•Parent VLAN ID. The parent VLAN for this VLAN, available only for VLANs of type FDDI or Token Ring when source-route bridging (SRB) is configured for use on this VLAN. This field is disabled for VLANs of Ethernet type. For Token Ring VLANs, enter the trBrf VLAN number here.

•Translational VLAN1 Number. A VLAN to which this VLAN is being translationally bridged. For VLANs of Ethernet type, enter any existing VLAN number from the original VLAN & Bridge window's table. This field is disabled for Token Ring VLANs.

•Translational VLAN2 Number. Another VLAN to which this VLAN is being translationally bridged. This field is disabled for Token Ring VLANs.

•VLAN Bridge Type. The type of the bridging mode in use on this VLAN. Choose either srt for source-route transparent bridging or srb for source-route bridging.

•VLAN ARE Hop Count (1...14). The maximum number of bridge hops in All Routes Explorer frames on this VLAN. This field is applicable to FDDI and Token Ring VLANs.

•VLAN STE Hop Count (1...14). The maximum number of bridge hops allowed in Spanning Tree Explorer frames on this VLAN. This field is applicable to FDDI and Token Ring VLANs.

•Backup CRF. Choose On if this VLAN is of type trCrf and also is acting as a backup trCrf for the ISL-distributed BRF.

Step4From the VLAN & Bridge table, select the newly created VLAN and click Modify VLAN.

Step5Change the Preferred VLAN value to yes and click Apply.

Step6Use the drag and drop technique to assign the ports to the VLAN.

Step7Click Apply to save the input and refresh the VLAN & Bridge table. If the device returns any errors during this operation, CiscoView displays the information.

Step8Repeat Steps 1 through 3 and Steps 6 and 7 for each new VLAN on the Catalyst5000 series switch, and Steps 1 through 7 for each new VLAN on the Catalyst3000 series switch.

Step9Click Cancel to exit the window.

Delete VLAN

To delete a VLAN, perform the following steps:

Step1From the VLAN & Bridge table, select a VLAN, and click Delete. A confirmation window opens.

NoteRemoval of a VLAN deactivates all the ports in the VLAN.

Step2Click Apply to confirm the deletion of the VLAN or Cancel to exit the window. If deleted, the VLAN is removed from the device VLAN table.

Step3Click Cancel to exit the window.

Modify VLAN

To modify a VLAN, select a VLAN from the VLAN table and click Modify VLAN. A dialog box similar to the one for creating a VLAN appears.

For additional information on the fields in the windows, click Help to access the online help.

To modify a VLAN, perform the following steps:

Step1From the VLAN & Bridge table, select a VLAN and click Modify VLAN. A dialog box similar to the one for creating VLAN appears.

Step2Change the value(s) as appropriate and click Apply. If the device returns any errors during this operation, CiscoView displays the information.

Step3Click Cancel to exit the window.