Usage Guidelines

The undebug sw-vlan command is the same as the no debug sw-vlan command.

Usage Guidelines

The undebug sw-vlan ifs command is the same as the no debug sw-vlan ifs command.

When selecting the file read operation, Operation 1 reads the file header, which contains the header verification word and the file version number. Operation 2 reads the main body of the file, which contains most of the domain and VLAN information. Operation 3 reads type length version (TLV) descriptor structures. Operation 4 reads TLV data.

Usage Guidelines

The undebug sw-vlan notification command is the same as the no debug sw-vlan notification command.

When you enable debugging on a switch stack, it is enabled only on the active switch. To debug a specific stack member, you can start a CLI session from the active switch by using the session switch stack-member-number privileged EXEC command.

Usage Guidelines

The undebug sw-vlan vtp command is the same as the no debug sw-vlan vtp command.

If no additional parameters are entered after the pruning keyword, VTP pruning debugging messages appear. They are generated by the VTP_PRUNING_LOG_NOTICE, VTP_PRUNING_LOG_INFO, VTP_PRUNING_LOG_DEBUG, VTP_PRUNING_LOG_ALERT, and VTP_PRUNING_LOG_WARNING macros in the VTP pruning code.

When you enable debugging on a switch stack, it is enabled only on the active switch. To debug a specific stack member, you can start a CLI session from the active switch by using the session switch stack-member-number privileged EXEC command.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes proper task IDs. If you suspect that user group assignment is preventing you from using a command, contact your AAA administrator.

The dot1q vlan native command defines the default, or native VLAN, associated with an 802.1Q trunk interface. The native VLAN of a trunk interface is the VLAN to which all the untagged VLAN packets are logically assigned.

Note	The native VLAN cannot be configured on a subinterface of the trunk interface. The native VLAN must be configured with the same value at both ends of the link, or traffic can be lost or sent to the wrong VLAN.

Usage Guidelines

To use this command, you must be in a user group associated with a task group that includes the proper task IDs. If you suspect user group assignment is preventing you from using a command, contact your AAA administrator.

To configure a large number of subinterfaces, we recommend entering all configuration data before you commit the interface command.

To change an interface from Layer 2 to Layer 3 mode and back, you must delete the interface first and then re-configure it in the appropriate mode.

Usage Guidelines

Before configuring private VLANs, you must disable VTP (VTP mode transparent). After you configure a private VLAN, you should not change the VTP mode to client or server.

VTP does not propagate private VLAN configurations. You must manually configure private VLANs on all switches in the Layer 2 network to merge their Layer 2 databases and to prevent flooding of private VLAN traffic.

You cannot include VLAN 1 or VLANs 1002 to 1005 in the private VLAN configuration. Extended VLANs (VLAN IDs 1006 to 4094) can be configured in private VLANs.

You can associate a secondary (isolated or community) VLAN with only one primary VLAN. A primary VLAN can have one isolated VLAN and multiple community VLANs associated with it.

• A secondary VLAN cannot be configured as a primary VLAN.

• The secondary-vlan-list cannot contain spaces. It can contain multiple comma-separated items. Each item can be a single private VLAN ID or a hyphenated range of private VLAN IDs. The list can contain one isolated VLAN and multiple community VLANs.

• If you delete either the primary or secondary VLANs, the ports associated with the VLAN become inactive.

A community VLAN carries traffic among community ports and from community ports to the promiscuous ports on the corresponding primary VLAN.

An isolated VLAN is used by isolated ports to communicate with promiscuous ports. It does not carry traffic to other community ports or isolated ports with the same primary VLAN domain.

A primary VLAN is the VLAN that carries traffic from a gateway to customer end stations on private ports.

Configure Layer 3 VLAN interfaces (SVIs) only for primary VLANs. You cannot configure Layer 3 VLAN interfaces for secondary VLANs. SVIs for secondary VLANs are inactive while the VLAN is configured as a secondary VLAN.

The private-vlan commands do not take effect until you exit from VLAN configuration mode.

Do not configure private VLAN ports as EtherChannels. While a port is part of the private VLAN configuration, any EtherChannel configuration for it is inactive.

Do not configure a private VLAN as a Remote Switched Port Analyzer (RSPAN) VLAN.

Do not configure a private VLAN as a voice VLAN.

Do not configure fallback bridging on switches with private VLANs.

Although a private VLAN contains more than one VLAN, only one STP instance runs for the entire private VLAN. When a secondary VLAN is associated with the primary VLAN, the STP parameters of the primary VLAN are propagated to the secondary VLAN.

For more information about private VLAN interaction with other features, see the software configuration guide for this release.

Usage Guidelines

The device must be in VTP transparent mode when you configure private VLANs.

The SVI of the primary VLAN is created at Layer 3.

Configure Layer 3 VLAN interfaces (SVIs) only for primary VLANs. You cannot configure Layer 3 VLAN interfaces for secondary VLANs. SVIs for secondary VLANs are inactive while the VLAN is configured as a secondary VLAN.

The secondary-vlan-list argument cannot contain spaces. It can contain multiple comma-separated items. Each item can be a single private VLAN ID or a hyphenated range of private VLAN IDs. The list can contain one isolated VLAN and multiple community VLANs.

Traffic that is received on the secondary VLAN is routed by the SVI of the primary VLAN.

A secondary VLAN can be mapped to only one primary SVI. If you configure the primary VLAN as a secondary VLAN, all SVIs specified in this command are brought down.

If you configure a mapping between two VLANs that do not have a valid Layer 2 private VLAN association, the mapping configuration does not take effect.

Usage Guidelines

In the show vlan mtu command output, the MTU_Mismatch column shows whether all the ports in the VLAN have the same MTU. When yes appears in the column, it means that the VLAN has ports with different MTUs, and packets that are switched from a port with a larger MTU to a port with a smaller MTU might be dropped. If the VLAN does not have an SVI, the hyphen (-) symbol appears in the SVI_MTU column. If the MTU-Mismatch column displays yes, the names of the ports with the MinMTU and the MaxMTU appear.

If you try to associate a private VLAN secondary VLAN with a primary VLAN before you define the secondary VLAN, the secondary VLAN is not included in the show vlan private-vlan command output.

In the show vlan private-vlan type command output, a type displayed as normal means a VLAN that has a private VLAN association but is not part of the private VLAN. For example, if you define and associate two VLANs as primary and secondary VLANs and then delete the secondary VLAN configuration without removing the association from the primary VLAN, the VLAN that was the secondary VLAN is shown as normal in the display. In the show vlan private-vlan output, the primary and secondary VLAN pair is shown as nonoperational.

Usage Guidelines

A private-VLAN host or promiscuous port cannot be a Switched Port Analyzer (SPAN) destination port. If you configure a SPAN destination port as a private-VLAN host or promiscuous port, the port becomes inactive.

Do not configure private VLAN on ports with these other features:

• Dynamic-access port VLAN membership

• Dynamic Trunking Protocol (DTP)

• Port Aggregation Protocol (PAgP)

• Link Aggregation Control Protocol (LACP)

• Multicast VLAN Registration (MVR)

• Voice VLAN

While a port is part of the private-VLAN configuration, any EtherChannel configuration for it is inactive

A private-VLAN port cannot be a secure port and should not be configured as a protected port.

For more information about private-VLAN interaction with other features, see the software configuration guide for this release.

We strongly recommend that you enable spanning tree Port Fast and bridge-protocol-data-unit (BPDU) guard on isolated and community host ports to prevent STP loops due to misconfigurations and to speed up STP convergence.

If you configure a port as a private-VLAN host port and you do not configure a valid private-VLAN association by using the switchport private-vlan host-association command, the interface becomes inactive.

If you configure a port as a private-VLAN promiscuous port and you do not configure a valid private VLAN mapping by using theswitchport private-vlan mapping command, the interface becomes inactive.

Usage Guidelines

When voice VLAN is enabled, you can configure the device to send the Cisco Discovery Protocol (CDP) packets to instruct the IP phone how to send data packets from the device attached to the access port on the Cisco IP Phone. You must enable CDP on the device port connected to the Cisco IP Phone to send the configuration to the Cisco IP Phone. (CDP is enabled by default globally and on all device interfaces.)

You should configure voice VLAN on the device access ports.

Usage Guidelines

The vlan-list format is all | none | [add | remove | except] vlan-atom [,vlan-atom...] :

• all specifies all VLANs from 1 to 4094. This is the default. This keyword is not allowed on commands that do not permit all VLANs in the list to be set at the same time.

• none specifies an empty list. This keyword is not allowed on commands that require certain VLANs to be set or at least one VLAN to be set.

• add adds the defined list of VLANs to those currently set instead of replacing the list. Valid IDs are from 1 to 1005; extended-range VLANs (VLAN IDs greater than 1005) are valid in some cases.

  Note	You can add extended-range VLANs to the allowed VLAN list, but not to the pruning-eligible VLAN list.

  Separate nonconsecutive VLAN IDs with a comma; use a hyphen to designate a range of IDs.

• remove removes the defined list of VLANs from those currently set instead of replacing the list. Valid IDs are from 1 to 1005; extended-range VLAN IDs are valid in some cases.

  Note	You can remove extended-range VLANs from the allowed VLAN list, but you cannot remove them from the pruning-eligible list.

• except lists the VLANs that should be calculated by inverting the defined list of VLANs. (VLANs are added except the ones specified.) Valid IDs are from 1 to 1005. Separate nonconsecutive VLAN IDs with a comma; use a hyphen to designate a range of IDs.

• vlan-atom is either a single VLAN number from 1 to 4094 or a continuous range of VLANs described by two VLAN numbers, the lesser one first, separated by a hyphen.

Native VLANs:

• All untagged traffic received on an IEEE 802.1Q trunk port is forwarded with the native VLAN configured for the port.

• If a packet has a VLAN ID that is the same as the sending-port native VLAN ID, the packet is sent without a tag; otherwise, the switch sends the packet with a tag.

• The no form of the native vlan command resets the native mode VLAN to the appropriate default VLAN for the device.

Allowed VLAN:

• To reduce the risk of spanning-tree loops or storms, you can disable VLAN 1 on any individual VLAN trunk port by removing VLAN 1 from the allowed list. When you remove VLAN 1 from a trunk port, the interface continues to send and receive management traffic, for example, Cisco Discovery Protocol (CDP), Port Aggregation Protocol (PAgP), Link Aggregation Control Protocol (LACP), Dynamic Trunking Protocol (DTP), and VLAN Trunking Protocol (VTP) in VLAN 1.

• The no form of the allowed vlan command resets the list to the default list, which allows all VLANs.

Trunk pruning:

• The pruning-eligible list applies only to trunk ports.

• Each trunk port has its own eligibility list.

• If you do not want a VLAN to be pruned, remove it from the pruning-eligible list. VLANs that are pruning-ineligible receive flooded traffic.

• VLAN 1, VLANs 1002 to 1005, and extended-range VLANs (VLANs 1006 to 4094) cannot be pruned.

Usage Guidelines

You can use the vlan vlan-id global configuration command to add normal-range VLANs (VLAN IDs 1 to 1005) or extended-range VLANs (VLAN IDs 1006 to 4094). Configuration information for normal-range VLANs is always saved in the VLAN database, and you can display this information by entering the show vlan privileged EXEC command. If the VTP mode is transparent, VLAN configuration information for normal-range VLANs is also saved in the running configuration file. VLAN IDs in the extended range are not saved in the VLAN database, but they are stored in the switch running configuration file, and you can save the configuration in the startup configuration file.

VTP version 3 supports propagation of extended-range VLANs. VTP versions 1 and 2 propagate only VLANs 1 to 1005.

When you save the VLAN and VTP configurations in the startup configuration file and reboot the , the configuration is selected as follows:

• If the VTP mode is transparent in the startup configuration and the VLAN database and the VTP domain name from the VLAN database matches that in the startup configuration file, the VLAN database is ignored (cleared), and the VTP and VLAN configurations in the startup configuration file are used. The VLAN database revision number remains unchanged in the VLAN database.

• If the VTP mode or domain name in the startup configuration do not match the VLAN database, the domain name and VTP mode and configuration for VLAN IDs 1 to 1005 use the VLAN database information.

If you enter an invalid VLAN ID, you receive an error message and do not enter VLAN configuration mode.

Entering the vlan command with a VLAN ID enables VLAN configuration mode. When you enter the VLAN ID of an existing VLAN, you do not create a new VLAN, but you can modify VLAN parameters for that VLAN. The specified VLANs are added or modified when you exit the VLAN configuration mode. Only the shutdown command (for VLANs 1 to 1005) takes effect immediately.

Note	Although all commands are visible, the only VLAN configuration commands that are supported on extended-range VLANs are mtu mtu-size and remote-span . For extended-range VLANs, all other characteristics must remain at the default state.

These configuration commands are available in VLAN configuration mode. The no form of each command returns the characteristic to its default state:

• are are-number —Defines the maximum number of all-routes explorer (ARE) hops for this VLAN. This keyword applies only to TrCRF VLANs. The range is 0 to 13. The default is 7. If no value is entered, 0 is assumed to be the maximum.

• backupcrf —Specifies the backup CRF mode. This keyword applies only to TrCRF VLANs.

  • enable —Backup CRF mode for this VLAN.

  • disable —Backup CRF mode for this VLAN (the default).

• bridge {bridge-number | type} —Specifies the logical distributed source-routing bridge, the bridge that interconnects all logical rings that have this VLAN as a parent VLAN in FDDI-NET, Token Ring-NET, and TrBRF VLANs. The range is 0 to 15. The default bridge number is 0 (no source-routing bridge) for FDDI-NET, TrBRF, and Token Ring-NET VLANs. The type keyword applies only to TrCRF VLANs and is one of these:

  • srb —Ssource-route bridging

  • srt —Source-route transparent) bridging VLAN

• exit —Applies changes, increments the VLAN database revision number (VLANs 1 to 1005 only), and exits VLAN configuration mode.

• media —Defines the VLAN media type and is one of these:

  Note	The supports only Ethernet ports. You configure only FDDI and Token Ring media-specific characteristics for VLAN Trunking Protocol (VTP) global advertisements to other . These VLANs are locally suspended.

  • ethernet —Ethernet media type (the default).

  • fd-net —FDDI network entity title (NET) media type.

  • fddi —FDDI media type.

  • tokenring —Token Ring media type if the VTP v2 mode is disabled, or TrCRF if the VTP Version 2 (v) mode is enabled.

  • tr-net —Token Ring network entity title (NET) media type if the VTP v2 mode is disabled or TrBRF media type if the VTP v2 mode is enabled.

  See the table that follows for valid commands and syntax for different media types.

• mtu mtu-size —Specifies the maximum transmission unit (MTU) (packet size in bytes). The range is 576 to 18190. The default is 1500 bytes.

• name vlan-name —Names the VLAN with an ASCII string from 1 to 32 characters that must be unique within the administrative domain. The default is VLANxxxx where xxxx represents four numeric digits (including leading zeros) equal to the VLAN ID number.

• no —Negates a command or returns it to the default setting.

• parent parent-vlan-id —Specifies the parent VLAN of an existing FDDI, Token Ring, or TrCRF VLAN. This parameter identifies the TrBRF to which a TrCRF belongs and is required when defining a TrCRF. The range is 0 to 1005. The default parent VLAN ID is 0 (no parent VLAN) for FDDI and Token Ring VLANs. For both Token Ring and TrCRF VLANs, the parent VLAN ID must already exist in the database and be associated with a Token Ring-NET or TrBRF VLAN.

• remote-span —Configures the VLAN as a Remote SPAN (RSPAN) VLAN. When the RSPAN feature is added to an existing VLAN, the VLAN is first deleted and is then recreated with the RSPAN feature. Any access ports are deactivated until the RSPAN feature is removed. If VTP is enabled, the new RSPAN VLAN is propagated by VTP for VLAN IDs that are lower than 1024. Learning is disabled on the VLAN.

• ring ring-number —Defines the logical ring for an FDDI, Token Ring, or TrCRF VLAN. The range is 1 to 4095. The default for Token Ring VLANs is 0. For FDDI VLANs, there is no default.

• said said-value —Specifies the security association identifier (SAID) as documented in IEEE 802.10. The range is 1 to 4294967294, and the number must be unique within the administrative domain. The default value is 100000 plus the VLAN ID number.

• shutdown —Shuts down VLAN switching on the VLAN. This command takes effect immediately. Other commands take effect when you exit VLAN configuration mode.

• state —Specifies the VLAN state:

  • active means the VLAN is operational (the default).

  • suspend means the VLAN is suspended. Suspended VLANs do not pass packets.

• ste ste-number —Defines the maximum number of spanning-tree explorer (STE) hops. This keyword applies only to TrCRF VLANs. The range is 0 to 13. The default is 7.

• stp type —Defines the spanning-tree type for FDDI-NET, Token Ring-NET, or TrBRF VLANs. For FDDI-NET VLANs, the default STP type is ieee. For Token Ring-NET VLANs, the default STP type is ibm. For FDDI and Token Ring VLANs, the default is no type specified.

  • ieee —IEEE Ethernet STP running source-route transparent (SRT) bridging.

  • ibm —IBM STP running source-route bridging (SRB).

  • auto —STP running a combination of source-route transparent bridging (IEEE) and source-route bridging (IBM).

• tb-vlan1 tb-vlan1-id and tb-vlan2 tb-vlan2-id —Specifies the first and second VLAN to which this VLAN is translationally bridged. Translational VLANs translate FDDI or Token Ring to Ethernet, for example. The range is 0 to 1005. If no value is specified, 0 (no transitional bridging) is assumed.

The following table describes the rules for configuring VLANs:

Usage Guidelines

When enabled, native VLAN packets going out of all IEEE 802.1Q trunk ports are tagged.

When disabled, native VLAN packets going out of all IEEE 802.1Q trunk ports are not tagged.

For more information about IEEE 802.1Q tunneling, see the software configuration guide for this release.

Usage Guidelines

When you save VTP mode, domain name, and VLAN configurations in the device startup configuration file and reboot the device, the VTP and VLAN configurations are selected by these conditions:

• If the VTP mode is transparent in the startup configuration and the VLAN database and the VTP domain name from the VLAN database matches that in the startup configuration file, the VLAN database is ignored (cleared), and the VTP and VLAN configurations in the startup configuration file are used. The VLAN database revision number remains unchanged in the VLAN database.

• If the VTP mode or domain name in the startup configuration do not match the VLAN database, the domain name and VTP mode and configuration for VLAN IDs 1 to 1005 use the VLAN database information.

The vtp file filename cannot be used to load a new database; it renames only the file in which the existing database is stored.

Follow these guidelines when configuring a VTP domain name:

• The device is in the no-management-domain state until you configure a domain name. While in the no-management-domain state, the device does not send any VTP advertisements even if changes occur to the local VLAN configuration. The device leaves the no-management-domain state after it receives the first VTP summary packet on any port that is trunking or after you configure a domain name by using the vtp domain command. If the device receives its domain from a summary packet, it resets its configuration revision number to 0. After the device leaves the no-management-domain state, it cannot be configured to reenter it until you clear the NVRAM and reload the software.

• Domain names are case-sensitive.

• After you configure a domain name, it cannot be removed. You can only reassign it to a different domain.

Follow these guidelines when setting VTP mode:

• The no vtp mode command returns the device to VTP server mode.

• The vtp mode server command is the same as no vtp mode except that it does not return an error if the device is not in client or transparent mode.

• If the receiving device is in client mode, the client device changes its configuration to duplicate the configuration of the server. If you have devices in client mode, be sure to make all VTP or VLAN configuration changes on a device in server mode, as it has a higher VTP configuration revision number. If the receiving device is in transparent mode, the device configuration is not changed.

• A device in transparent mode does not participate in VTP. If you make VTP or VLAN configuration changes on a device in transparent mode, the changes are not propagated to other devices in the network.

• If you change the VTP or VLAN configuration on a device that is in server mode, that change is propagated to all the devices in the same VTP domain.

• The vtp mode transparent command disables VTP from the domain but does not remove the domain from the device.

• In VTP Versions 1 and 2, the VTP mode must be transparent for VTP and VLAN information to be saved in the running configuration file.

• With VTP Versions 1 and 2, you cannot change the VTP mode to client or server if extended-range VLANs are configured on the switch. Changing the VTP mode is allowed with extended VLANs in VTP Version 3.

• The VTP mode must be transparent for you to add extended-range VLANs or for VTP and VLAN information to be saved in the running configuration file.

• VTP can be set to either server or client mode only when dynamic VLAN creation is disabled.

• The vtp mode off command sets the device to off. The no vtp mode off command resets the device to the VTP server mode.

Follow these guidelines when setting a VTP password:

• Passwords are case sensitive. Passwords should match on all devices in the same domain.

• When you use the no vtp password form of the command, the device returns to the no-password state.

• The hidden and secret keywords are supported only in VTP Version 3. If you convert from VTP Version 2 to VTP Version 3, you must remove the hidden or secret keyword before the conversion.

Follow these guidelines when setting VTP pruning:

• VTP pruning removes information about each pruning-eligible VLAN from VTP updates if there are no stations belonging to that VLAN.

• If you enable pruning on the VTP server, it is enabled for the entire management domain for VLAN IDs 1 to 1005.

• Only VLANs in the pruning-eligible list can be pruned.

• Pruning is supported with VTP Version 1 and Version 2.

Follow these guidelines when setting the VTP version:

• Toggling the Version 2 (v2) mode state modifies parameters of certain default VLANs.

• Each VTP device automatically detects the capabilities of all the other VTP devices. To use Version 2, all VTP devices in the network must support Version 2; otherwise, you must configure them to operate in VTP Version 1 mode.

• If all devices in a domain are VTP Version 2-capable, you only need to configure Version 2 on one device; the version number is then propagated to the other Version-2 capable devices in the VTP domain.

• If you are using VTP in a Token Ring environment, VTP Version 2 must be enabled.

• If you are configuring a Token Ring bridge relay function (TrBRF) or Token Ring concentrator relay function (TrCRF) VLAN media type, you must use Version 2.

• If you are configuring a Token Ring or Token Ring-NET VLAN media type, you must use Version 1.

• In VTP Version 3, all database VTP information is propagated across the VTP domain, not only VLAN database information.

• Two VTP Version 3 regions can only communicate over a VTP Version 1 or VTP Version 2 region in transparent mode.

You cannot save password, pruning, and version configurations in the device configuration file.

Usage Guidelines

Enter this command only on interfaces that are in trunking mode.

Usage Guidelines

A VTP primary server updates the database information and sends updates that are honored by all devices in the system. A VTP secondary server can only back up the updated VTP configurations received from the primary server to NVRAM.

By default, all devices come up as secondary servers. Primary server status is needed only for database updates when the administrator issues a takeover message in the domain. You can have a working VTP domain without any primary servers.

Primary server status is lost if the device reloads or domain parameters change.

Note	This command is supported only when the device is running VTP Version 3.