# VLAN & Bridge

Device>Configure>VLAN & Bridge

Virtual LANs (VLANs) allow you to logically group resources independent of their physical location. This arrangement of resources, and the ports to which they are attached, is called a logical grouping. A logical group of ports is called a VLAN. Ports or groups of ports in a VLAN are called members. VLANs isolate all traffic, including broadcasts and multicasts, from being propagated to members of other VLANs. A Token Ring VLAN comprises Token Ring Bridge Relay Functions (trBRFs) and Token Ring Concentrator Relay Functions (trCRFs).

Note: Extended range VLAN values (1025-4094) are supported by Catalyst 4000 devices running Catalyst OS version 7.2 or later and Catalyst 6000 devices running Catalyst OS version 6.1 or later.

If the switches are interconnected by a port called an Inter-Switch Link (ISL), you can specify which VLANs are allowed to flow through the ISL.

You can use the VLAN & Bridge option to configure and view VLANs and their members.

The table on the left side of the dialog box displays the following information:

VLAN Number (VlanNumber)

Numeric VLAN Trunking Protocol (VTP) ID.

VLAN Name (vtpVlanName)

ASCII name associated with the VLAN; synonymous with the VLAN’s emulated LAN name on LAN emulation (LANE) trunks.

VLAN Type (vtpVlanType)

Possible VLAN Type values: ethernet, Fiber Distributed Data Interface (fddi), tokenRing (trCRF), fddiNet, trNet (trBRF).

VLAN State (vtpVlanState)

Current state of the VLAN. Possible values are Operational and Suspended. VLANs in Operational state are functional. VLANs in Suspended state do not pass packets.

Private VLAN Type (cpvlanVlanPrivateVlanType)

Indicates the VLAN type as defined for Private VLAN feature.

Primary VLAN (cpvlanVlanAssociatedPrimaryVlan)

The VLAN ID of the associated primary VLAN used for the Private VLAN feature if Primary VLAN (cpvlanVlanPrivateVlanType) has the value of isolated(3) or community(4). If Primary VLAN (cpvlanVlanPrivateVlanType) has the value of normal(1) or primary(2), then this object has the value of 0.

RSPAN VLAN (vtpVlanTypeExtProp)

Indicates if the current VLAN is RSPAN VLAN or not. Possible values are yes or no. Default value should be no.

Button Options

The View Ports buttons at the upper right of the dialog box have the following functions:

VLAN Members

To display the ports on the switch that belong to a specified VLAN, select the number of the VLAN for which you want to display members, then click VLAN Members. The ports that belong to the VLAN are highlighted on the device display. The count includes both logical and physical ports, but CiscoView does not highlight the logical ports.

Inter Switch

To display ports in a VLAN shared across switches, click Inter Switch.

Clear Ports

To clear the highlighting, click Clear Ports.

VLAN Non-Trunk Members

To display the ports on the switch that belong to a specified VLAN but are not trunk ports, select the number of the VLAN for which you want to display member, then click VLAN Non-Trunk Members.

The Bridge buttons have the following functions:

Configure

Forwarding (This option is not available for trBRFs.)

Static (This option is not available for trBRFs or trCRFs.)

The VTP-VLAN buttons at the bottom of the dialog box allow you to perform the following tasks with VLANs on a Catalyst 5000, 5500, or 6000:

Local Mgmt Domain

Create VLAN

Delete VLAN

Modify VLAN

The SVI Group Configure button allows you to view, create or modify switched virtual interfaces.

The VLAN Group Configure button allows you to view, create or modify VLAN groups.

Note: The VLAN Group configure feature is supported only by IOS.

To move a port to a different VLAN, drag the port with the middle mouse button (the left button for PC users) pressed and release it when the mouse pointer is over the desired entry in the VLAN table. To select multiple ports, select the first port as usual and then hold down the CONTROL key as you select additional ports.

Click Cancel to close the dialog box without making any changes. Click Print to print the contents of the dialog box.

# Token Ring VLANs

Within a Token Ring virtual LAN (VLAN), distributed rings can be formed by defining groups of ports that have the same ring number. The IEEE calls such a port group a Token Ring Concentrator Relay Function (trCRF). A trCRF is limited to the ports in a single Catalyst 5000 series switch.

Within the trCRF, source-route switching is used for forwarding based on either MAC addresses or route descriptors. If desired, the entire VLAN can operate as a single ring. Frames can be switched between ports within a single trCRF.

Multiple trCRFs can be interconnected using a single Token Ring Bridge Relay Function (trBRF). For source routing, the switch appears as a single bridge between the logical rings. The trBRF can function as a source-route bridge (SRB) or source-route transparent (SRT) bridge running either the IBM or IEEE Spanning-Tree Protocol. If SRB is used, duplicate MAC addresses can be defined on different distributed rings.

To accommodate SNA traffic, you can use a combination of SRT and SRB modes. In a mixed mode the trBRF considers some ports (internal ports connected to trCRFs) to be operating in SRB mode while others are operating in SRT mode.

The trBRF can be extended across a network of switches via high-speed uplinks between the switches. These links must have the ability to multiplex multiple VLANs and provide the necessary information to support logical rings.

# Bridge

Device>Configure>VLAN & Bridge>Configure

Most of the configuration required in bridging is related to the Spanning Tree Algorithm. The Spanning Tree Algorithm allows the connected network topology to contain multiple physical paths between two stations, but constrains the active topology to be a single-span tree. If a port on one bridge fails, the other bridges can reconfigure the topology and switch traffic over to new paths.

If the Spanning Tree feature is not enabled, no backup path exists to maintain bridge connectivity.

To display or change bridging configuration for a device, click Configure in the VLAN & Bridge dialog box.

The dialog box displays the following information:

Bridge Address (dot1dBaseBridgeAddress)

MAC address of the bridge.

Bridge Type (dot1dBaseType)

Type of bridging that this bridge can do. The possible values are unknown, transparent-only, sourceroute-only, and srt (source route transparent bridging).

Forwarding DB Learn Discards (dot1dTpLearnedEntryDiscards)

Number of Forwarding Database entries that have been or would have been learned but were discarded because of lack of space.

Spanning Tree (vlanSpantreeEnable)

Whether the Spanning Tree feature is enabled or disabled. If disabled, transparent bridging is used.

Forwarding DB Aging (secs) (dot1dTpAgingTime)

Timeout value in seconds after which dynamically-learned forwarding information is removed from the bridge’s forwarding database. Possible values range from 10 through 1,000,000 seconds, and the recommended default is 300 seconds.

Spanning Tree Protocol (dot1dStpProtocol)

Version of the Spanning Tree Protocol being used. The possible values are unknown, decLb100, or ieee80221d. The unknown value usually indicates an error.

Priority (dot1dStpPriority)

Integer that is the first two octets of the bridge identifier.

Last Topology Change (dot1dStpTimeSinceTopologyChange)

Date and time that the last topology change was made.

Topology Changes (dot1dStpTopChanges)

Total number of topology changes by this bridge since it was last reset or initialized.

Designated Root (dot1dStpDesignatedRoot)

Bridge identifier of the node that this bridge indicates is the current root of the spanning tree.

Root Cost (dot1dStpRootCost)

Integer that represents the total cost of the best path to the root.

Root Port (dot1dStpRootPort)

Port number through which the lowest-cost path to the root is accessed.

Max Age (dot1dStpMaxAge)

Timeout value for STP information learned from the network. After this interval, information that has not been refreshed will be discarded.

Hello Time (dot1dStpHelloTime)

Interval for sending configuration bridge PDUs if the bridge is the root or is trying to become the root.

Hold Time (dot1dStpHoldTime)

Interval at which a maximum of two configuration bridge PDUs are transmitted by this node.

Forward Delay (dot1dStpForwardDelay)

Time for this port to spend in each of the listening and learning states in preparation for going into the forwarding state.

Bridge Max Age (dot1dStpBridgeMaxAge)

Value that all bridges use for the maximum age timeout when this bridge is the root. Possible values are from 6 to 40 seconds.

Note: If the device is in MISTP mode, Bridge Max Age (dot1dStpBridgeMaxAge) can not be set on a per VLAN basis.

Bridge Hello Time (dot1dStpBridgeHelloTime)

Interval that all bridges use for hello time when this bridge is the root. Possible values are from 1 to 10 seconds.

Note: If the device is in MISTP mode, Bridge Hello Time (dot1dStpBridgeHelloTime) can not be set on a per VLAN basis.

Bridge Forward Delay (dot1dStpBridgeForwardDelay)

Value used by all bridges for the forward delay interval when this bridge is the root bridge. Possible values are from 4 to 30 seconds.

Note: If the device is in MISTP mode, Bridge Forward Delay (dot1dStpBridgeForwardDelay) can not be set on a per VLAN basis.

Click Apply to make your changes take effect. Click Cancel to close the dialog box without making any changes. Click Print to print the contents of the dialog box.

# Bridge Forwarding

Device>Configure>VLAN & Bridge>Bridge Forwarding

To display bridge forwarding information for a device, click Bridge Forwarding from the VLAN & Bridge dialog box.

The Bridge Forwarding dialog box displays the following information:

MAC Address (dot1dTpFdbAddress)

Unicast MAC address of destinations that are reachable by the port.

Port (dot1dTpFdbPort)

Port to which frames with that destination MAC address should be forwarded.

Status (dot1dTpFdbStatus)

How the entry or destination became known to the bridge. Possible values are learned, self, mgmt, or other. Learned information can include both dynamic and static entries. Self indicates the MAC address of a port on this bridge. Mgmt means that this address is in the static table or database for the bridge.

Click Cancel to close the dialog box without making any changes. Click Print to print the contents of the dialog box.

# Bridge Static

Device>Configure>VLAN & Bridge>Bridge Forwarding

The bridge static table displays forwarding information that has been manually configured on the bridge. The table shows the destination address, the port through which the bridge will forward traffic to that destination, and the status of the entry.

To display bridge static information for a device, if the device supports the bridge static table, click Static in the VLAN & Bridge dialog box.

The Bridge Static dialog box displays the following information:

MAC Address (dot1dStaticAddress)

Destination MAC addresses that have been added to the database or table and to which the filtering/VLAN information applies. A MAC address consists of 6 bytes. The first three bytes identify the vendor.

Port (dot1dStaticReceivePort)

Port number from which a frame must be received for filtering to occur. The value 0 indicates that frames can be received from all ports on the bridge. For example, 1.6 means that card 1, port 6 is forwarding information for this port.

Allowed Ports (dot1dStaticAllowedToGoTo)

Set of ports through which forwarding is allowed. For example, the entry 1, 3, 7-10 indicates that ports 1, 3, 7, 8, 9, and 10 forward information for this port.

Status (dot1dStaticStatus)

Whether the entry is permanent or which conditions cause it to be removed. Possible values are permanent, deleteOnReset, deleteOnTimeout, or other.

Click Cancel to close the dialog box without making any changes. Click Print to print the contents of the dialog box.

# VTP Mgmt Domain

Device>Configure>VLAN & Bridge>Local Management Domain

The VTP Mgmt Domain dialog box contains the following information about the local management domain:

Management Domain Index (managementDomainIndex)

Index value identifying this domain on the local system.

Management Domain Name (managementDomainName)

Management name of a domain in which this system is participating. This value is required.

Working Mode of Local System (managementDomainLocalMode)

Whether the local system is acting as a VTP client or a VTP server in this management domain. A value of transparent indicates that a device cannot support VTP for this domain.

Configuration Revision Number (managementDomainConfigRevNumber)

Current configuration revision number for this management domain.

Revision # Last Updater (managementDomainLastUpdater)

IP address of the VTP server that last updated the configuration revision number.

Revision # Last Change (managementDomainLastChange)

Time at which the configuration revision number was last increased to its current value.

VTP Pruning State (managementDomainPruningState)

Displays whether VTP Pruning is enabled or disabled. When enabled, pruning limits the scope of the broadcast traffic across trunk links.

Current Version of VTP in Use (managementDomainVersionInUse)

Displays the version number of the current VTP Management Domain.

Click Apply to make your changes take effect, or click Cancel to close the dialog box without making any changes.

# Create VLAN

Device>Configure>VLAN & Bridge>Create VLAN

To create a VLAN, first make sure that a local management domain name is defined. (Click Local Mgmt Domain in the VLAN & Bridge dialog box to verify this.) Then, enter the following information in the Create VLAN dialog box:

Depending on the type of virtual LAN (VLAN) you are creating, some of the information in this dialog box will vary.

VLAN Number (vtpVlanIndex)

VLAN ID of this VLAN. Accepted values are as follows:

- for Catalyst 4000 devices running Catalyst OS version 7.1 or earlier, 2 through 1,000.

- for Catalyst 4000 devices running Catalyst OS version 7.2 or later and Catalyst 6000 devices running Catalyst OS version 6.1 or later, 2 through 1,000 and 1025 through 4094.

Consult your hardware user guide for more information on appropriate VLAN numbers.

VLAN State (vtpVlanState)

State of this VLAN: Operational or Suspended.

VLAN Type (vtpVlanType)

Possible VLAN Type values: ethernet, Fiber Distributed Data Interface (fddi), tokenRing (trCRF), fddiNet, trNet (trBRF).

VLAN Name (vtpVlanName)

Name of this VLAN. The name can be up to 16 characters.

MTU Size (vtpVlanMtu)

Size of the largest MAC-layer data frame that can be transmitted on this VLAN.

802.10 SAID Field (vtpVlanDot10Said)

Value of the 802.10 Security Association ID (SAID) field for this VLAN. This number is usually the same as the VLAN number. This field is not displayed when creating a trBRF or trCRF.

If you are defining an Ethernet VLAN, the following additional information is displayed:

Ring Number (vtpVlanRingNumber)

Ring number of this VLAN.

Bridge Number (vtpVlanBridgeNumber)

The bridge number of the VTP-capable switches for this VLAN.

STP Type (vtpVlanStpType)

The STP type indicates the type of Spanning Tree Protocol (STP) running on this VLAN. This object is only instanciated when the value of the corresponding instance of vtpVlanType has a value of 'fddiNet' or 'trNet'.

Parent VLAN (vtpVlanParentVlan)

Parent VLAN for this VLAN.

Translational VLAN1 (vtpVlanTranslationalVlan1)

A VLAN to which this VLAN is being translationally bridged. The associated VLAN type cannot be the same as the VLAN that is being modified or created.

Translational VLAN2 (vtpVlanTranslationalVlan2)

Another VLAN to which this VLAN is being translationally bridged.

If you are defining an fddi VLAN or a trCRF VLAN, the following additional information is displayed:

Bridging Mode (vtpVlanBridgeType)

Bridging mode for this VLAN. Possible values are source-route transparent (SRT) bridging and source-route bridging (SRB). The default is SRB.

Maximum Hops in STE Frames (vtpVlanSteHopCount)

Maximum number of hops for spanning-tree explorer frames. Possible values are 1 through 14. The default is 7.

Maximum Hops in ARE Frames (vtpVlanAreHopCount)

Maximum number of hops for all-routes explorer frames. Possible values are 1 through 14. The default is 7.

trCRF Backup Type (vtpVlanIsCRFBackup)

Displays the trCRF backup path for traffic. This field applies to trCRFs only.

Private VLAN Type (cpvlanVlanPrivateVlanType)

Indicates the VLAN type as defined for Private VLAN feature.

Primary VLAN (cpvlanVlanAssociatedPrimaryVlan)

The VLAN ID of the associated primary VLAN used for the Private VLAN feature if Primary VLAN (cpvlanVlanPrivateVlanType) has the value of isolated(3) or community(4). If Primary VLAN (cpvlanVlanPrivateVlanType) has the value of normal(1) or primary(2), then this object has the value of 0.

Spanning Tree Status (stpxPVSTVlanEnable)

Indicates whether Spanning Tree PVST+ Protocol is enabled for this Virtual LAN.

Note: For Cat5K and Cat5500 supervisor with EARL-2 and later hardware: If Spanning Tree is disabled for one VLAN, it will be disabled for all VLANs.

Rspan VLAN (vtpVlanTypeExt)

Provides additional type information of this VLAN.

Click OK to add a new VLAN, or click Cancel to close the dialog box without making any changes.

# Delete VLAN

Device>Configure>VLAN & Bridge>Delete VLAN

Click Apply to delete this VLAN definition, or click Cancel to close this dialog box. Clicking Help displays this help message.

# Modify VLAN

Device>Configure>VLAN & Bridge>Modify VLAN

To change the characteristics of a VLAN, change the appropriate fields in the Modify VLAN dialog box:

Depending on the type of VLAN you are changing, some of the information in this dialog box will vary.

VLAN Number (vtpVlanIndex)

VLAN ID of this VLAN. Consult your hardware user guide for more information on appropriate VLAN numbers.

VLAN State (vtpVlanState)

State of this VLAN: Operational or Suspended.

VLAN Type (vtpVlanType)

Possible VLAN Type values: ethernet, Fiber Distributed Data Interface (fddi), tokenRing (trCRF), fddiNet, trNet (trBRF).

VLAN Name (vtpVlanName)

Name of this VLAN. The name can be up to 16 characters.

MTU Size (vtpVlanMtu)

Size of the largest MAC-layer data frame that can be transmitted on this VLAN.

802.10 SAID Field (vtpVlanDot10Said)

Value of the 802.10 Security Association ID (SAID) field for this VLAN. This number is usually the same as the VLAN number. This field is not displayed when creating a trBRF or trCRF.

If you are defining an Ethernet VLAN, the following additional information is displayed:

Ring Number (vtpVlanRingNumber)

Ring number of this VLAN.

Bridge Number (vtpVlanBridgeNumber)

The bridge number of the VTP-capable switches for this VLAN.

STP Type (vtpVlanStpType)

The STP type indicates the type of Spanning Tree Protocol (STP) running on this VLAN. This object is only instanciated when the value of the corresponding instance of vtpVlanType has a value of 'fddiNet' or 'trNet'.

Parent VLAN (vtpVlanParentVlan)

Parent VLAN for this VLAN.

Translational VLAN1 (vtpVlanTranslationalVlan1)

A VLAN to which this VLAN is being translationally bridged. The associated VLAN type cannot be the same as the VLAN that is being modified or created.

Translational VLAN2 (vtpVlanTranslationalVlan2)

Another VLAN to which this VLAN is being translationally bridged. The associated VLAN type cannot be the same as the VLAN that is being modified or created.

If you are defining an fddi VLAN or a trCRF VLAN, the following additional information is displayed:

Bridging Mode (vtpVlanBridgeType)

Bridging mode for this VLAN. Possible values are source-route transparent (SRT) bridging and source-route bridging (SRB). The default is SRB.

Maximum Hops in STE Frames (vtpVlanSteHopCount)

Maximum number of hops for spanning-tree explorer frames. Possible values are 1 through 14. The default is 7.

Maximum Hops in ARE Frames (vtpVlanAreHopCount)

Maximum number of hops for all-routes explorer frames. Possible values are 1 through 14. The default is 7.

trCRF Backup Type (vtpVlanIsCRFBackup)

Displays the trCRF backup path for traffic. This field applies to trCRFs only.

Spanning Tree Status (stpxPVSTVlanEnable)

Indicates whether Spanning Tree PVST+ Protocol is enabled for this Virtual LAN.

Note: For Cat5K and Cat5500 supervisor with EARL-2 and later hardware: If Spanning Tree is disabled for one VLAN, it will be disabled for all VLANs.

Private VLAN Type (cpvlanVlanPrivateVlanType)

Indicates the VLAN type as defined for Private VLAN feature.

Primary VLAN (cpvlanVlanAssociatedPrimaryVlan)

The VLAN ID of the associated primary VLAN used for the Private VLAN feature if Primary VLAN (cpvlanVlanPrivateVlanType) has the value of isolated(3) or community(4). If Primary VLAN (cpvlanVlanPrivateVlanType) has the value of normal(1) or primary(2), then this object has the value of 0.

Click OK to add a new VLAN, or click Cancel to close the dialog box without making any changes.