Catalyst 4500 Series Switch Cisco IOS Command Reference, 12.2(25)EW
snmp ifindex clear through vtp v2-mode
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2.2

Table Of Contents

snmp ifindex clear

snmp ifindex persist

snmp-server enable traps

snmp-server ifindex persist

snmp-server ifindex persist compress

spanning-tree backbonefast

spanning-tree bpdufilter

spanning-tree bpduguard

spanning-tree cost

spanning-tree etherchannel guard misconfig

spanning-tree extend system-id

spanning-tree guard

spanning-tree link-type

spanning-tree loopguard default

spanning-tree mode

spanning-tree mst

spanning-tree mst configuration

spanning-tree mst forward-time

spanning-tree mst hello-time

spanning-tree mst max-age

spanning-tree mst max-hops

spanning-tree mst root

spanning-tree pathcost method

spanning-tree portfast (interface configuration mode)

spanning-tree portfast bpdufilter default

spanning-tree portfast bpduguard default

spanning-tree portfast default

spanning-tree port-priority

spanning-tree uplinkfast

spanning-tree vlan

speed

storm-control

storm-control broadcast include multicast

switchport

switchport access vlan

switchport block

switchport mode

switchport port-security

switchport private-vlan association trunk

switchport private-vlan host-association

switchport private-vlan mapping

switchport private-vlan trunk allowed vlan

switchport private-vlan trunk native vlan tag

switchport trunk

system mtu

traceroute mac

traceroute mac ip

tx-queue

udld (global configuration mode)

udld (interface configuration mode)

udld reset

unidirectional

username

verify

vlan (VLAN Database mode)

vlan access-map

vlan database

vlan dot1q tag native

vlan filter

vlan internal allocation policy

vmps reconfirm (global configuration)

vmps reconfirm (privileged EXEC)

vmps retry

vmps server

vtp (global configuration mode)

vtp client

vtp domain

vtp password

vtp pruning

vtp server

vtp transparent

vtp v2-mode


2.2

snmp ifindex clear

To clear any previously configured snmp ifindex commands that were entered for a specific interface, use the snmp ifindex clear command.

snmp ifindex clear

Syntax Description

This command has no arguments or keywords.

Defaults

This command has no default settings.

Command Modes

Interface configuration mode

Command History

Release
Modification

12.1(19)EW

Support for this command was introduced on the Catalyst 4500 series switches.


Usage Guidelines

Interface index persistence occurs when ifIndex values in the interface MIB (IF-MIB) persist across reboots and allow for consistent identification of specific interfaces using SNMP.

Use the snmp ifindex clear command on a specific interface when you want that interface to use the global configuration setting for ifIndex persistence. This command clears any ifIndex configuration commands previously entered for that specific interface.

Examples

This example shows how to enable ifIndex persistence for all interfaces:

Router(config)# snmp-server ifindex persist

This example shows how to disable IfIndex persistence for FastEthernet 1/1 only:

Router(config)# interface fastethernet 1/1
Router(config-if)# no snmp ifindex persist
Router(config-if)# exit

This example shows how to clear the ifIndex configuration from the FastEthernet 1/1 configuration:

Router(config)# interface fastethernet 1/1
Router(config-if)# snmp ifindex clear
Router(config-if)# exit

As a result of this sequence of commands, ifIndex persistence is enabled for all interfaces that are specified by the snmp-server ifindex persist global configuration command.

Related Commands

snmp ifindex persist
snmp-server ifindex persist

snmp ifindex persist

To enable ifIndex values in the Interfaces MIB (IF-MIB) that persist across reboots (ifIndex persistence) on a specific interface, use the snmp ifindex persist command. To disable ifIndex persistence only on a specific interface, use the no form of this command.

snmp ifindex persist

no snmp ifindex persist

Syntax Description

This command has no arguments or keywords.

Defaults

Disabled.

Command Modes

Interface configuration mode

Command History

Release
Modification

12.1(19)EW

Support for this command was introduced on the Catalyst 4500 series switches.


Usage Guidelines

Interface index persistence occurs when ifIndex values in the IF-MIB persist across reboots and allow for consistent identification of specific interfaces using SNMP.

The snmp ifindex persist interface configuration command enables and disables ifIndex persistence for individual entries (that correspond to individual interfaces) in the ifIndex table of the IF-MIB.

The snmp-server ifindex persist global configuration command enables and disables ifIndex persistence for all interfaces on the routing device. This action applies only to interfaces that have ifDescr and ifIndex entries in the ifIndex table of the IF-MIB.

Examples

This example shows how to enable ifIndex persistence for interface FastEthernet 1/1 only:

Router(config)# interface fastethernet 1/1
Router(config-if)# snmp ifindex persist
Router(config-if)# exit

This example shows how to enable ifIndex persistence for all interfaces, and then disable ifIndex persistence for interface FastEthernet 1/1 only:

Router(config)# snmp-server ifindex persist
Router(config)# interface fastethernet 1/1
Router(config-if)# no snmp ifindex persist
Router(config-if)# exit

Related Commands

snmp-server enable traps

To enable SNMP notifications (traps or informs), use the snmp-server enable traps command. To disable all SNMP notifications, use the no form of this command.

snmp-server enable traps [flash [insertion | removal] | fru-ctrl |
port-security
[trap-rate trap-rate] | removal | stpx | vlancreate | vlandelete | vtp]

no snmp-server enable traps flash [insertion | removal] | fru-ctrl | port-security [trap-rate trap-rate] | removal | stpx | vlancreate | vlandelete | vtp]

Syntax Description

flash

(Optional) Controls the SNMP FLASH trap notifications.

insertion

(Optional) Controls the SNMP Flash insertion trap notifications.

removal

(Optional) Controls the SNMP Flash removal trap notifications.

fru-ctrl

(Optional) Controls the SNMP entity FRU control trap notifications.

port-security

(Optional) Controls the SNMP trap generation.

trap-rate trap-rate

(Optional) Sets the number of traps per second.

stpx

(Optional) Controls all the traps defined in CISCO-STP-EXTENSIONS-MIB notifications.

vlancreate

(Optional) Controls the SNMP VLAN created trap notifications.

vlandelete

(Optional) Controls the SNMP VLAN deleted trap notifications.

vtp

(Optional) Controls the SNMP VTP trap notifications.


Defaults

SNMP notifications are disabled.

Command Modes

Global configuration

Command History

Release
Modification

12.1(13)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

If you enter this command without an option, all notification types controlled by this command are enabled.

SNMP notifications can be sent as traps or inform requests. This command enables both traps and inform requests for the specified notification types. To specify whether the notifications should be sent as traps or informs, use the snmp-server host [traps | informs] command.

The snmp-server enable traps command is used in conjunction with the snmp-server host command. Use the snmp-server host command to specify which host or hosts receive SNMP notifications. To send notifications, you must configure at least one snmp-server host command.

This list of the MIBs is used for the traps:

flash—Controls SNMP FLASH traps from the CISCO-FLASH-MIB.

insertion—Controls the SNMP Flash insertion trap notifications.

removal—Controls the SNMP Flash removal trap notifications.

fru-ctrl—Controls the FRU control traps from the CISCO-ENTITY-FRU-CONTROL-MIB.

port-security—Controls the port-security traps from the CISCO-PORT-SECURITY-MIB.

stpx—Controls all the traps from the CISCO-STP-EXTENSIONS-MIB.

vlancreate—Controls SNMP VLAN created trap notifications.

vlandelete—Controls SNMP VLAN deleted trap notifications.

vtp—Controls the VTP traps from the CISCO-VTP-MIB.

Examples

This example shows how to send all traps to the host is specified by the name myhost.cisco.com using the community string defined as public:

Switch(config)# snmp-server enable traps 
Switch(config)# snmp-server host myhost.cisco.com public
Switch(config)#  

Related Commands

Refer to Cisco IOS documentation for additional snmp-server enable traps commands.

snmp-server ifindex persist

To globally enable ifIndex values that will remain constant across reboots for use by SNMP, use the snmp-server ifindex persist command. To globally disable inIndex persistence, use the no form of this command.

snmp-server ifindex persist

no snmp-server ifindex persist

Syntax Description

This command has no arguments or keywords.

Defaults

Disabled.

Command Modes

Global configuration mode

Command History

Release
Modification

12.1(19)EW

Support for this command was introduced on the Catalyst 4500 series switches.


Usage Guidelines

Interface index persistence occurs when ifIndex values in the IF-MIB persist across reboots and allow for consistent identification of specific interfaces using SNMP.

The snmp-server ifindex persist global configuration command does not override the interface-specific configuration. To override the interface-specific configuration of ifIndex persistence, enter the no snmp ifindex persist and snmp ifindex clear interface configuration commands.

Entering the no snmp-server ifindex persist global configuration command enables and disables ifIndex persistence for all interfaces on the routing device using ifDescr and ifIndex entries in the ifIndex table of the IF-MIB.

Examples

This example shows how to enable ifIndex persistence for all interfaces:

Router(config)# snmp-server ifindex persist

Related Commands

snmp-server ifindex persist compress

To configure the format of the ifIndex table in a compressed format, use the snmp-server ifindex persist compress command. To place the table in a decompressed format, use the no form of this command.

snmp-server ifindex persist compress

no snmp-server ifindex persist compress

Syntax Description

This command has no arguments or keywords.

Defaults

Disabled

Command Modes

Global configuration mode.

Command History

Release
Modification

12.2(20)EWA

Support for this command was introduced on the Catalyst 4500 series switches.


Usage Guidelines

This command is hidden on Supervisor Engine V and later supervisor engines because the ifIndex table is always in a compressed format on those supervisor engines.

At bootup, if the nvram:ifIndex-table.gz file (the ifIndex table ina compressed format) is present on a Supervisor Engine II+, Supervisor Engine III, or Supervisor Engine IV, the snmp-server ifindex persist compress command is automatically run even if the startup-config file does not have this configuration.

Examples

This example shows how to enable compression of the ifIndex table:

Router(config)# snmp-server ifindex persist compress

This example shows how to disable compression of the ifIndex table:

Router(config)# no snmp-server ifindex persist compress

Related Commands

spanning-tree backbonefast

To enable BackboneFast on a spanning-tree VLAN, use the spanning-tree backbonefast command. To disable BackboneFast, use the no form of this command.

spanning-tree backbonefast

no spanning-tree backbonefast

Syntax Description

This command has no arguments or keywords.

Defaults

BackboneFast is disabled.

Command Modes

Global configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

BackboneFast should be enabled on all Catalyst 4006 family switches to allow the detection of indirect link failures. Enabling BackboneFast starts the spanning-tree reconfiguration more quickly.

Examples

This example shows how to enable BackboneFast on all VLANs:

Switch(config)# spanning-tree backbonefast
Switch(config)# 

Related Commands

spanning-tree cost
spanning-tree port-priority
spanning-tree portfast default
spanning-tree portfast (interface configuration mode)
spanning-tree uplinkfast
spanning-tree vlan
show spanning-tree

spanning-tree bpdufilter

To enable BPDU filtering on an interface, use the spanning-tree bpdufilter command. To return to the default settings, use the no form of this command.

spanning-tree bpdufilter {enable | disable}

no spanning-tree bpdufilter

Syntax Description

enable

Enables BPDU filtering on this interface.

disable

Disables BPDU filtering on this interface.


Defaults

Disabled

Command Modes

Interface configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines


Caution Use care when entering the spanning-tree bpdufilter enable command. Enabling BPDU filtering on an interface is approximately equivalent to disabling the spanning tree for this interface. It is possible to create bridging loops if this command is not correctly used.

When configuring Layer 2 protocol tunneling on all the service provider edge switches, you must enable spanning-tree BPDU filtering on the 802.1Q tunnel ports by entering the spanning-tree bpdufilter enable command.

BPDU filtering allows you to prevent a port from sending and receiving BPDUs. The configuration is applicable to the whole interface, whether it is trunking or not. This command has three states:

spanning-tree bpdufilter enableThis state unconditionally enables the BPDU filter feature on the interface.

spanning-tree bpdufilter disableThis state unconditionally disables the BPDU filter feature on the interface.

no spanning-tree bpdufilterThis state enables the BPDU filter feature on the interface if the interface is in operational PortFast state and if the spanning-tree portfast bpdufilter default command is configured.

Examples

This example shows how to enable the BPDU filter feature on this interface:

Switch(config-if)# spanning-tree bpdufilter enable
Switch(config-if)# 

Related Commands

show spanning-tree
spanning-tree portfast bpdufilter default

spanning-tree bpduguard

To enable BPDU guard on an interface, use the spanning-tree bpduguard command. To return to the default settings, use the no form of this command.

spanning-tree bpduguard {enable | disable}

no spanning-tree bpduguard

Syntax Description

enable

Enables BPDU guard on this interface.

disable

Disables BPDU guard on this interface.


Defaults

BPDU guard is disabled.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

BPDU guard is a feature that prevents a port from receiving BPDUs. This feature is typically used in a service provider environment where the administrator wants to prevent an access port from participating in the spanning tree. If the port still receives a BPDU, it is put in the ErrDisable state as a protective measure. This command has three states:

spanning-tree bpduguard enableThis state unconditionally enables BPDU guard on the interface.

spanning-tree bpduguard disableThis state unconditionally disables BPDU guard on the interface.

no spanning-tree bpduguard—This state enables BPDU guard on the interface if it is in the operational PortFast state and if the spanning-tree portfast bpduguard default command is configured.

Examples

This example shows how to enable BPDU guard on this interface:

Switch(config-if)# spanning-tree bpduguard enable
Switch(config-if)# 

Related Commands

show spanning-tree
spanning-tree portfast bpduguard default

spanning-tree cost

To calculate the path cost of STP on an interface, use the spanning-tree cost command. To revert to the default, use the no form of this command.

spanning-tree cost cost

no spanning-tree cost cost

Syntax Description

cost

Path cost; valid values are from 1 to 200,000,000.


Defaults

The default settings are as follows:

FastEthernet—19

GigabitEthernet—1

Command Modes

Interface configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

When you configure the cost, the higher values indicate higher costs. The range applies regardless of the protocol type that is specified. The path cost is calculated, based on the interface bandwidth.

Examples

This example shows how to access an interface and set a path cost value of 250 for the spanning-tree VLAN that is associated with that interface:

Switch(config)# interface fastethernet 2/1
Switch(config-if)# spanning-tree cost 250
Switch(config-if)# 

Related Commands

spanning-tree port-priority
spanning-tree portfast default
spanning-tree portfast (interface configuration mode)
spanning-tree uplinkfast
spanning-tree vlan
show spanning-tree

spanning-tree etherchannel guard misconfig

To display an error message when a loop due to a channel misconfiguration is detected, use the spanning-tree etherchannel guard misconfig command. To disable the feature, use the no form of this command.

spanning-tree etherchannel guard misconfig

no spanning-tree etherchannel guard misconfig

Syntax Description

This command has no arguments or keywords.

Defaults

Spanning-tree EtherChannel guard is enabled.

Command Modes

Global configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

When an EtherChannel guard misconfiguration is detected, this message is displayed:

%SPANTREE-2-CHNL_MISCFG:Detected loop due to etherchannel misconfig of interface 
Port-Channel1

To determine which local ports are involved in the misconfiguration, enter the show interfaces status err-disabled command. To check the EtherChannel configuration on the remote device, enter the show etherchannel summary command on the remote device.

After you correct the configuration, enter the shutdown and the no shutdown commands on the associated port-channel interface.

Examples

This example shows how to enable the EtherChannel guard misconfiguration feature:

Switch(config)# spanning-tree etherchannel guard misconfig
Switch(config)# 

Related Commands

show etherchannel
show interfaces status
shutdown
(refer to Cisco IOS documentation)

spanning-tree extend system-id

To enable the extended system ID feature on a chassis that supports 1024 MAC addresses, use the spanning-tree extend system-id command. To disable the feature, use the no form of this command.

spanning-tree extend system-id

no spanning-tree extend system-id

Syntax Description

This command has no arguments or keywords.

Defaults

Enabled on systems that do not provide 1024 MAC addresses.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

Releases 12.1(13)E and later support chassis with 64 or 1024 MAC addresses. For chassis with 64 MAC addresses, STP uses the extended system ID plus a MAC address to make the bridge ID unique for each VLAN.

You cannot disable the extended system ID on chassis that support 64 MAC addresses.

Enabling or disabling the extended system ID updates the bridge IDs of all active STP instances, which might change the spanning-tree topology.

Examples

This example shows how to enable the extended system ID:

Switch(config)# spanning-tree extend system-id 
Switch(config)# 

Related Commands

show spanning-tree

spanning-tree guard

To enable root guard, use the spanning-tree guard command. To disable root guard, use the no form of this command.

spanning-tree guard {loop | root | none}

no spanning-tree guard

Syntax Description

loop

Enables the loop guard mode on the interface.

root

Enables root guard mode on the interface.

none

Sets the guard mode to none.


Defaults

Root guard is disabled.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.1(12c)EW

Loop guard support was added.


Examples

This example shows how to enable root guard:

Switch(config-if)# spanning-tree guard root
Switch(config-if)# 

Related Commands

show spanning-tree

spanning-tree link-type

To configure a link type for a port, use the spanning-tree link-type command. To return to the default settings, use the no form of this command.

spanning-tree link-type {point-to-point | shared}

no spanning-tree link-type

Syntax Description

point-to-point

Specifies that the interface is a point-to-point link.

shared

Specifies that the interface is a shared medium.


Defaults

Link type is derived from the duplex mode.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

RSTP+ fast transition works only on point-to-point links between two bridges.

By default, the switch derives the link type of a port from the duplex mode. A full-duplex port is considered as a point-to-point link while a half-duplex configuration is assumed to be on a shared link.

If you designate a port as a shared link, RSTP+ fast transition is forbidden, regardless of the duplex setting.

Examples

This example shows how to configure the port as a shared link:

Switch(config-if)# spanning-tree link-type shared
Switch(config-if)# 

Related Commands

show spanning-tree interface

spanning-tree loopguard default

To enable loop guard as the default on all ports of a specific bridge, use the spanning-tree loopguard default command. To disable loop guard, use the no form of this command.

spanning-tree loopguard default

no spanning-tree loopguard default

Syntax Description

This command has no keywords or arguments.

Defaults

Loop guard is disabled.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

Loop guard provides an additional security in the bridge network. Loop guard prevents alternate or root ports from becoming the designated port because of a failure leading to a unidirectional link.

Loop guard operates only on ports that are considered point-to-point by the spanning tree.

Individual loop-guard port configuration overrides this global default.

Examples

This example shows how to enable loop guard:

Switch(config)# spanning-tree loopguard default
Switch(config)# 

Related Commands

show spanning-tree
spanning-tree guard

spanning-tree mode

To switch between PVST+ and MST modes, use the spanning-tree mode command. To return to the default settings, use the no form of this command.

spanning-tree mode {pvst | mst | rapid-pvst}

no spanning-tree mode {pvst | mst | rapid-pvst}

Syntax Description

pvst

Specifies PVST+ mode.

mst

Specifies MST mode.

rapid-pvst

Specifies Rapid PVST mode.


Defaults

PVST+ mode

Command Modes

Configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.1(19)EW

Support for the rapid-pvst keyword.


Usage Guidelines


Caution Be careful when using the spanning-tree mode command to switch between PVST+ and MST modes. When you enter the command, all spanning-tree instances are stopped for the previous mode and restarted in the new mode. Using this command may cause disruption of user traffic.

Examples

This example shows how to switch to MST mode:

Switch(config)# spanning-tree mode mst
Switch(config)# 

This example shows how to return to the default mode (PVST):

Switch(config)# no spanning-tree mode
Switch(config)# 

Related Commands

show spanning-tree mst

spanning-tree mst

To set the path cost and port-priority parameters for any MST instance (including the CIST with instance ID 0), use the spanning-tree mst command. To return to the default settings, use the no form of this command.

spanning-tree mst instance-id [cost cost] | [port-priority prio]

no spanning-tree mst instance-id {cost | port-priority}

Syntax Description

instance-id

Instance ID number; valid values are from 0 to 15.

cost cost

(Optional) Specifies the path cost for an instance; valid values are from 1 to 200000000.

port-priority prio

(Optional) Specifies the port priority for an instance; valid values are from 0 to 240 in increments of 16.


Defaults

Port priority is 128.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

The higher cost cost values indicate higher costs. When entering the cost value, do not include a comma in the entry; for example, enter 1000, not 1,000.

The higher port-priority prio values indicate smaller priorities.

By default, the cost depends on the port speed; faster interface speeds indicate smaller costs. MST always uses long path costs.

Examples

This example shows how to set the interface path cost:

Switch(config-if)# spanning-tree mst 0 cost 17031970
Switch(config-if)# 

This example shows how to set the interface priority:

Switch(config-if)# spanning-tree mst 0 port-priority 64
Switch(config-if)# 

Related Commands

show spanning-tree mst
spanning-tree port-priority

spanning-tree mst configuration

To enter the MST configuration submode, use the spanning-tree mst configuration command. To return to the default MST configuration, use the no form of this command.

spanning-tree mst configuration

no spanning-tree mst configuration

Syntax Description

This command has no arguments or keywords.

Defaults

The default settings are as follows:

No VLANs are mapped to any MST instance.

All VLANs are mapped to the CIST instance.

The region name is an empty string.

The revision number is 0.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

The MST configuration consists of three main parameters:

Instance VLAN mapping (see the instance command)

Region name (see the name command)

Configuration revision number (see the revision command)

By default, the value for the MST configuration is the default value for all its parameters.

The abort and exit commands allow you to exit the MST configuration submode. The difference between the two commands depends on whether you want to save your changes or not.

The exit command commits all the changes before leaving MST configuration submode. If you do not map the secondary VLANs to the same instance as the associated primary VLAN, when you exit the MST configuration submode, a message displays and lists the secondary VLANs that are not mapped to the same instance as the associated primary VLAN. The message is as follows:

These secondary vlans are not mapped to the same instance as their primary:
->3

The abort command leaves the MST configuration submode without committing any changes.

Whenever you change an MST configuration submode parameter, it can cause a loss of connectivity. To reduce the number of service disruptions, when you enter the MST configuration submode, you are changing a copy of the current MST configuration. When you are done editing the configuration, you can apply all the changes at once by using the exit keyword, or you can exit the submode without committing any change to the configuration by using the abort keyword.

In the unlikely event that two users enter a new configuration at exactly at the same time, this message is displayed:

Switch(config-mst)# exit
% MST CFG:Configuration change lost because of concurrent access
Switch(config-mst)# 

Examples

This example shows how to enter the MST configuration submode:

Switch(config)# spanning-tree mst configuration
Switch(config-mst)# 

This example shows how to reset the MST configuration to the default settings:

Switch(config)# no spanning-tree mst configuration
Switch(config)# 

Related Commands

instance
name
revision
show spanning-tree mst


spanning-tree mst forward-time

To set the forward delay timer for all the instances, use the spanning-tree mst forward-time command. To return to the default settings, use the no form of this command.

spanning-tree mst forward-time seconds

no spanning-tree mst forward-time

Syntax Description

seconds

Number of seconds to set the forward delay timer for all the instances on the Catalyst 4500 series switch; valid values are from 4 to 30 seconds.


Defaults

The forward delay timer is set for 15 seconds.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Examples

This example shows how to set the forward-delay timer:

Switch(config)# spanning-tree mst forward-time 20
Switch(config)# 

Related Commands

show spanning-tree mst

spanning-tree mst hello-time

To set the hello-time delay timer for all the instances, use the spanning-tree mst hello-time command. To return to the default settings, use the no form of this command.

spanning-tree mst hello-time seconds

no spanning-tree mst hello-time

Syntax Description

seconds

Number of seconds to set the hello-time delay timer for all the instances on the Catalyst 4500 series switch; valid values are from 1 to 10 seconds.


Defaults

The hello-time delay timer is set for 2 seconds.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

If you do not specify the hello-time value, the value is calculated from the network diameter.

Examples

This example shows how to set the hello-time delay timer:

Switch(config)# spanning-tree mst hello-time 3
Switch(config)# 

Related Commands

show spanning-tree mst

spanning-tree mst max-age

To set the max-age timer for all the instances, use the spanning-tree mst max-age command. To return to the default settings, use the no form of this command.

spanning-tree mst max-age seconds

no spanning-tree mst max-age

Syntax Description

seconds

Number of seconds to set the max-age timer for all the instances on the Catalyst 4500 series switch; valid values are from 6 to 40 seconds.


Defaults

The max-age timer is set for 20 seconds.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Examples

This example shows how to set the max-age timer:

Switch(config)# spanning-tree mst max-age 40
Switch(config)# 

Related Commands

show spanning-tree mst

spanning-tree mst max-hops

To specify the number of possible hops in the region before a BPDU is discarded, use the spanning-tree mst max-hops command. To return to the default settings, use the no form of this command.

spanning-tree mst max-hops hopnumber

no spanning-tree mst max-hops

Syntax Description

hopnumber

Number of possible hops in the region before a BPDU is discarded; valid values are from 1 to 40 hops.


Defaults

Number of hops is 20.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Examples

This example shows how to set the number of possible hops in the region before a BPDU is discarded to 25:

Switch(config)# spanning-tree mst max-hops 25
Switch(config)# 

Related Commands

show spanning-tree mst

spanning-tree mst root

To designate the primary root, secondary root, bridge priority, and timer value for an instance, use the spanning-tree mst root command. To return to the default settings, use the no form of this command.

spanning-tree mst instance-id root {primary | secondary} | {priority prio} [diameter dia [hello-time hello]]

no spanning-tree mst root

Syntax Description

instance-id

Instance identification number; valid values are from 1 to 15.

root

Configures switch as the root switch.

primary

Sets a high enough priority (low value) to make the bridge root of the spanning-tree instance.

secondary

Designates this switch as a secondary root if the primary root fails.

priority prio

Sets the bridge priority; see the "Usage Guidelines" section for valid values and additional information.

diameter dia

(Optional) Sets the timer values for the bridge based on the network diameter; valid values are from 2 to 7.

hello-time hello

(Optional) Specifies the duration between the generation of configuration messages by the root switch.


Defaults

Bridge priority is 32768.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

The bridge priority can be set in increments of 4096 only. When you set the priority, valid values are 0, 4096, 8192, 12288, 16384, 20480, 24576, 28672, 32768, 36864, 40960, 45056, 49152, 53248, 57344, and 61440.

You can set the priority to 0 to make the switch root.

The spanning-tree root secondary bridge priority value is 16384.

The diameter dia and hello-time hello options are available for instance 0 only.

If you do not specify the hello_time value, the value is calculated from the network diameter.

Examples

This example shows how to set the bridge priority:

Switch(config)# spanning-tree mst 0 root priority 4096
Switch(config)# 

This example shows how to set the priority and timer values for the bridge:

Switch(config)# spanning-tree mst 0 root primary diameter 7 hello-time 2
Switch(config)# spanning-tree mst 5 root primary
Switch(config)# 

Related Commands

show spanning-tree mst

spanning-tree pathcost method

To set the path cost calculation method, use the spanning-tree pathcost method command. To revert to the default setting, use the no form of this command.

spanning-tree pathcost method {long | short}

no spanning-tree pathcost method

Syntax Description

long

Specifies 32-bit-based values for port path costs.

short

Specifies 16-bit-based values for port path costs.


Defaults

Port path cost has 32-bit-based values.

Command Modes

Global configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

This command applies to all the spanning-tree instances on the switch.

The long path cost calculation method uses all the 32 bits for path cost calculation and yields values in the range of 1 through 200,000,000.

The short path cost calculation method (16 bits) yields values in the range of 1 through 65,535.

Examples

This example shows how to set the path cost calculation method to long:

Switch(config) spanning-tree pathcost method long
Switch(config)

This example shows how to set the path cost calculation method to short:

Switch(config) spanning-tree pathcost method short
Switch(config)

Related Commands

show spanning-tree

spanning-tree portfast (interface configuration mode)

To enable PortFast mode, where the interface is immediately put into the forwarding state upon linkup without waiting for the timer to expire, use the spanning-tree portfast command. To return to the default setting, use the no form of this command.

spanning-tree portfast {disable | trunk}

no spanning-tree portfast

Syntax Description

disable

Disables PortFast on the interface.

trunk

Enables PortFast on the interface even while in the trunk mode.


Defaults

PortFast mode is disabled.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.1(12c)EW

The disable and trunk options were added.


Usage Guidelines

You should use this feature only with interfaces that connect to end stations; otherwise, an accidental topology loop could cause a data packet loop and disrupt the Catalyst 4500 series switch and network operation.

An interface with PortFast mode enabled is moved directly to the spanning-tree forwarding state when linkup occurs without waiting for the standard forward-time delay.

Be careful when using the no spanning-tree portfast command. This command does not disable PortFast if the spanning-tree portfast default command is enabled.

This command has four states:

spanning-tree portfast—This command enables PortFast unconditionally on the given port.

spanning-tree portfast disable—This command explicitly disables PortFast for the given port. The configuration line shows up in the running-configuration as it is not the default.

spanning-tree portfast trunk—This command allows you to configure PortFast on trunk ports.


Note If you enter the spanning-tree portfast trunk command, the port is configured for PortFast even when in the access mode.


no spanning-tree portfast—This command implicitly enables PortFast if the spanning-tree portfast default command is defined in global configuration and if the port is not a trunk port. If you do not configure PortFast globally, the no spanning-tree portfast command is equivalent to the spanning-tree portfast disable command.

Examples

This example shows how to enable PortFast mode:

Switch(config-if)# spanning-tree portfast
Switch(config-if)

Related Commands

spanning-tree cost
spanning-tree port-priority
spanning-tree portfast default
spanning-tree uplinkfast
spanning-tree vlan
show spanning-tree

spanning-tree portfast bpdufilter default

To enable the BPDU filtering by default on all PortFast ports, use the spanning-tree portfast bpdufilter default command. To return to the default settings, use the no form of this command.

spanning-tree portfast bpdufilter default

no spanning-tree portfast bpdufilter default

Syntax Description

This command has no keywords or arguments.

Defaults

BPDU filtering is disabled.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

The spanning-tree portfast bpdufilter default command enables BPDU filtering globally on the Catalyst 4500 series switch. BPDU filtering prevents a port from sending or receiving any BPDUs.

You can override the effects of the spanning-tree portfast bpdufilter default command by configuring BPDU filtering at the interface level.


Note Be careful when enabling BPDU filtering. Functionality is different when enabling on a per-port basis or globally. When enabled globally, BPDU filtering is applied only on ports that are in an operational PortFast state. Ports still send a few BPDUs at linkup before they effectively filter outbound BPDUs. If a BPDU is received on an edge port, it immediately loses its operational PortFast status and BPDU filtering is disabled.

When enabled locally on a port, BPDU filtering prevents the Catalyst 4500 series switch from receiving or sending BPDUs on this port.



Caution Be careful when using this command. This command can cause bridging loops if not used correctly.

Examples

This example shows how to enable BPDU filtering by default:

Switch(config)# spanning-tree portfast bpdufilter default
Switch(config)# 

Related Commands

show spanning-tree mst
spanning-tree bpdufilter

spanning-tree portfast bpduguard default

To enable BPDU guard by default on all the PortFast ports, use the spanning-tree portfast bpduguard default command. To return to the default settings, use the no form of this command.

spanning-tree portfast bpduguard default

no spanning-tree portfast bpduguard default

Syntax Description

This command has no keywords or arguments.

Defaults

BPDU guard is disabled.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines


Caution Be careful when using this command. You should use this command only with the interfaces that connect to the end stations; otherwise, an accidental topology loop could cause a data packet loop and disrupt the Catalyst 4500 series switch and network operation.

BPDU guard disables a port if it receives a BPDU. BPDU guard is applied only on ports that are PortFast enabled and are in an operational PortFast state.

Examples

This example shows how to enable BPDU guard by default:

Switch(config)# spanning-tree portfast bpduguard default
Switch(config)# 

Related Commands

show spanning-tree mst
spanning-tree bpduguard

spanning-tree portfast default

To globally enable PortFast by default on all access ports, use the spanning-tree portfast default command. To disable PortFast as default on all access ports, use the no form of this command.

spanning-tree portfast default

no spanning-tree portfast default

Syntax Description

This command has no arguments or keywords.

Defaults

PortFast is disabled.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines


Caution Be careful when using this command. You should use this command only with the interfaces that connect to end stations; otherwise, an accidental topology loop could cause a data packet loop and disrupt the Catalyst 4500 series switch and network operation.

An interface with PortFast mode enabled is moved directly to the spanning-tree forwarding state when linkup occurs without waiting for the standard forward-time delay.

You can enable PortFast mode on individual interfaces using the spanning-tree portfast (interface configuration mode) command.

Examples

This example shows how to globally enable PortFast by default on all access ports:

Switch(config)# spanning-tree portfast default
Switch(config)# 

Related Commands

show spanning-tree
spanning-tree portfast (interface configuration mode)

spanning-tree port-priority

To prioritize an interface when two bridges compete for position as the root bridge, use the spanning-tree port-priority command. The priority you set breaks the tie. To revert to the default setting, use the no form of this command.

spanning-tree port-priority port_priority

no spanning-tree port-priority

Syntax Description

port_priority

Port priority; valid values are from 0 to 240 in increments of 16.


Defaults

Port priority value is set to 128.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Examples

This example shows how to increase the possibility that the spanning-tree instance 20 will be chosen as the root-bridge on interface FastEthernet 2/1:

Switch(config-if)# spanning-tree port-priority 0
Switch(config-if)# 

Related Commands

spanning-tree cost
spanning-tree portfast default
spanning-tree portfast (interface configuration mode)
spanning-tree uplinkfast
spanning-tree vlan
show spanning-tree

spanning-tree uplinkfast

To enable the UplinkFast feature, use the spanning-tree uplinkfast command. To disable UplinkFast, use the no form of this command.

spanning-tree uplinkfast [max-update-rate packets-per-second]

no spanning-tree uplinkfast [max-update-rate]

Syntax Description

max-update-rate packets_per_second

(Optional) Specifies the maximum rate (in packets per second) at which update packets are sent; valid values are from 0 to 65535.


Defaults

The default settings are as follows:

Disabled.

Maximum update rate is 150.

Command Modes

Global configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

This command should be used only on access switches.

When UplinkFast is configured, the bridge priority is changed to 49,152 so that this switch will not be selected as root. All interface path costs of all spanning-tree interfaces belonging to the specified spanning-tree instances are also increased by 3000.

When spanning tree detects that the root interface has failed, the UplinkFast feature causes an immediate switchover to an alternate root interface, transitioning the new root interface directly to the forwarding state. During this time, a topology change notification is sent. To minimize the disruption caused by the topology change, a multicast packet is sent to 01-00-0C-CD-CD-CD for each station address in the forwarding bridge except for those associated with the old root interface.

Use the spanning-tree uplinkfast max-update-rate command to enable UplinkFast (if not already enabled) and change the rate at which the update packets are sent. Use the no form of this command to return the default rate of 150 packets per second.

Examples

This example shows how to enable UplinkFast and set the maximum rate to 200 packets per second:

Switch(config)# spanning-tree uplinkfast 
Switch(config)# spanning-tree uplinkfast max-update-rate 200

Related Commands

spanning-tree cost
spanning-tree port-priority
spanning-tree portfast default
spanning-tree portfast (interface configuration mode)
spanning-tree vlan

spanning-tree vlan

To configure STP on a per-VLAN basis, use the spanning-tree vlan command. To return to the default value, use the no form of this command.

spanning-tree vlan vlan_id [forward-time seconds | hello-time seconds | max-age seconds | priority priority | protocol protocol | root {primary | secondary} [diameter net-diameter [hello-time seconds]]]

no spanning-tree vlan vlan_id [forward-time | hello-time | max-age | priority | root]

Syntax Description

vlan_id

VLAN identification number; valid values are from 1 to 4094.

forward-time seconds

(Optional) Sets the STP forward delay time; valid values are from 4 to 30 seconds.

hello-time seconds

(Optional) Specifies, in seconds, the time between configuration messages generated by the root switch; valid values are from 1 to 10 seconds.

max-age seconds

(Optional) Sets the maximum time, in seconds, that the information in a BPDU is valid; valid values are from 6 to 40 seconds.

priority priority

(Optional) Sets the STP bridge priority; valid values are from 0 to 65535.

protocol protocol

(Optional) Specifies the protocol.

root primary

(Optional) Forces this switch to be the root bridge.

root secondary

(Optional) Specifies this switch act as the root switch should the primary root fail.

diameter net-diameter

(Optional) Specifies the maximum number of bridges between two end stations; valid values are from 2 to 7.


Defaults

The default settings are as follows:

Forward-time—15 seconds

Hello-time—2 seconds

Max-age—20 seconds

Priority—32768 with STP enabled; 128 with MST enabled

Root—No STP root

Command Modes

Global configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.1(12c)EW

Support for extended addressing was added.


Usage Guidelines

When you are setting the max-age seconds value, if a bridge does not hear BPDUs from the root bridge within the specified interval, it assumes that the network has changed and recomputes the spanning-tree topology.

The spanning-tree root primary command alters the switch bridge priority to 8192. If you enter the spanning-tree root primary command and the switch does not become root, then the bridge priority is changed to 100 less than the bridge priority of the current bridge. If the switch does not become root, an error will result.

The spanning-tree root secondary command alters the switch bridge priority to 16384. If the root switch fails, this switch becomes the next root switch.

Use the spanning-tree root commands on backbone switches only.

Examples

This example shows how to enable spanning tree on VLAN 200:

Switch(config)# spanning-tree vlan 200 
Switch(config)# 

This example shows how to configure the switch as the root switch for VLAN 10 with a network diameter of 4:

Switch(config)# spanning-tree vlan 10 root primary diameter 4
Switch(config)# 

This example shows how to configure the switch as the secondary root switch for VLAN 10 with a network diameter of 4:

Switch(config)# spanning-tree vlan 10 root secondary diameter 4 
Switch(config)# 

Related Commands

spanning-tree cost
spanning-tree port-priority
spanning-tree portfast default
spanning-tree portfast (interface configuration mode)
spanning-tree uplinkfast
show spanning-tree

speed

To configure the interface speed, use the speed command. To disable a speed setting, use the no form of this command.

speed {10 | 100 | 1000 | auto [10 | 100 | 1000] | nonegotiate}

no speed

Syntax Description

10

(Optional) Configures the interface to transmit at 10 Mbps.

100

(Optional) Configures the interface to transmit at 100 Mbps.

1000

(Optional) Configures the interface to transmit at 1000 Mbps.

auto [10 | 100 | 1000]

(Optional) Enables the interface to autonegotiate the speed and specify the exact values to advertise when autonegotiating.

nonegotiate

(Optional) Enables the interface to not negotiate the speed.


Defaults

The default values are shown in the following table:

Interface Type
Supported Syntax
Default Setting

10/100-Mbps module

speed [10 | 100 | auto [10 | 100]]

Auto

100-Mbps fiber modules

Not applicable

Not applicable

Gigabit Ethernet Interface

speed nonegotiate

Nonegotiate

10/100/1000

speed [10 | 100 | 1000 | auto [10 | 100 | 1000]]

Auto

1000

Not applicable

Not applicable


Command Modes

Interface configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.2(20)EWA

Support for auto negotiating specific speeds added.


Usage Guidelines

Table 2-26 lists the supported command options by interface.

Table 2-26 Supported speed Command Options 

Interface Type
Supported Syntax
Default Setting
Guidelines

10/100-Mbps module

speed [10 | 100 | auto]

auto

If the speed is set to 10 or 100 and you do not configure the duplex setting, the duplex is set to half.

100-Mbps fiber modules

Not applicable.

Not applicable.

Not applicable.

Gigabit Ethernet Interface

speed nonegotiate

nonegotiate is enabled.

This is only applicable to Gigabit Ethernet ports.

10/100/1000

speed [10 | 100 | 1000 | auto]

auto

If the speed is set to 10 or 100 and you do not configure the duplex setting, the duplex is set to half.

If the speed is set to 1000 or auto with any subset containing 1000
(e.g.
speed auto 10 1000 or
speed auto on a 10/100/1000 port), you will not able to set half duplex.

1000

Not applicable.

Not applicable.

The speed is always 1000.

The duplex is half.


If you configure the interface speed and duplex commands manually and enter a value other than
speed auto (for example, 10 or 100 Mbps), make sure that you configure the connecting interface speed command to a matching speed but do not use the auto parameter.

When manually configuring the interface speed to either 10 or 100 Mbps, the switch prompts you to also configure duplex mode on the interface.


Note Catalyst 4006 switches cannot automatically negotiate the interface speed and the duplex mode if either connecting interface is configured to a value other than auto.



Caution Changing the interface speed and the duplex mode configuration might shut down and reenable the interface during the reconfiguration.

Table 2-27 describes the system's performance for different combinations of the duplex and speed modes. The specified duplex command that is configured with the specified speed command produces the resulting system action.

Table 2-27 System Action Using duplex and speed Commands 

duplex Command
speed Command
Resulting System Action

duplex auto

speed auto

Autonegotiates both speed and duplex modes

duplex half

speed 10

Forces 10 Mbps and half duplex

duplex full

speed 10

Forces 10 Mbps and full duplex

duplex half

speed 100

Forces 100 Mbps and half duplex

duplex full

speed 100

Forces 100 Mbps and full duplex

duplex full

speed 1000

Forces 1000 Mbps and full duplex


Examples

This example shows how to set the interface speed to 100 Mbps on the Fast Ethernet interface 5/4:

Switch(config)# interface fastethernet 5/4
Switch(config-if)# speed 100

This example shows how to allow Fast Ethernet interface 5/4 to autonegotiate the speed and duplex mode:

Switch(config)# interface fastethernet 5/4
Switch(config-if)# speed auto

Note The speed auto 10 100 command is similar to the speed auto command on a Fast Ethernet interface.


This example shows how to limit the interface speed to 10 and 100 Mbps on the Gigabit Ethernet interface 1/1 in auto-negotiation mode:

Switch(config)# interface gigabitethernet 1/1
Switch(config-if)# speed auto 10 100

This example shows how to limit the speed negotiation to 100 Mbps on the Gigabit Ethernet interface 1/1:

Switch(config)# interface gigabitethernet 1/1
Switch(config-if)# speed auto 100

Related Commands

duplex
interface
(refer to Cisco IOS documentation)
show controllers (refer to Cisco IOS documentation)
show interfaces (refer to Cisco IOS documentation)

storm-control

To enable broadcast storm control on a port and to specify what to do when a storm occurs on a port, use the storm-control interface configuration command. To disable storm control for the broadcast traffic and to disable a specified storm-control action, use the no form of this command.

storm-control {broadcast level high level [lower level]} | action {shutdown | trap}}

no storm-control {broadcast level level [lower level]} | action {shutdown | trap}}

Syntax Description

broadcast

Enables the broadcast storm control on the port.

level high-level lower-level

Defines the rising and falling suppression levels:

high-level—Rising suppression level as a percent of total bandwidth, up to two decimal places; valid values are from 0 to 100 percent. Blocks the flooding of storm packets when the value specified for level is reached.

lower-level—(Optional) Falling suppression level as a percent of total bandwidth, up to two decimal places; valid values are from 0 to 100. This value must be less than the rising supression value.

action

Directs the switch to take action when a storm occurs on a port.

shutdown

Disables the port during a storm.

trap

Sends an SNMP trap when a storm occurs. This keyword is available but not supported in 12.1(19)EW.


Defaults

Broadcast storm control is disabled. All packets are passed.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(19)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

Enter the storm-control broadcast level command to enable traffic storm control on the interface, configure the traffic storm control level, and apply the traffic storm control level to the broadcast traffic on the interface.

The Catalyst 4500 series switch supports broadcast traffic storm control on all LAN ports.

The period is required when you enter the fractional suppression level.

The suppression level is entered as a percentage of the total bandwidth. A threshold value of 100 percent indicates that no limit is placed on traffic. A value of 0.0 means that all specified traffic on that port is blocked.

Enter the show interfaces counters storm-control command to display the discard count.

Enter the show running-config command to display the enabled suppression mode and level setting.

To turn off suppression for the specified traffic type, you can do one of the following:

Set the high-level value to 100 percent for the specified traffic type.

Use the no form of this command.

The lower level is ignored for the interfaces that perform storm control in the hardware.

Examples

This example shows how to enable broadcast storm control on a port with a 75.67 percent rising suppression level:

Switch(config-if)# storm-control broadcast level 75.67

This example shows how to disable the port during a storm:

Switch(config-if)# storm-control action shutdown

This example shows how to disable storm control on a port:

Switch(config-if)# no storm-control broadcast level

This example shows how to disable storm control by setting the high level to 200 percent:

Switch(config-if)# storm-control broadcast level 200

Related Commands

show interfaces counters
show running-config

storm-control broadcast include multicast

To enable multicast storm control on a port, use the storm-control broadcast include multicast command. To disable multicast storm control, use the no form of this command.

storm-control broadcast include multicast

no storm-control broadcast include multicast

Syntax Description

This command has no arguments or keywords.

Defaults

Multicast storm control is disabled.

Command Modes

Global configuration

Command History

Release
Modification

12.2(18)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

This command prompts the hardware to filter multicast packets if it is already filtering broadcast packets.

Examples

This example shows how to enable multicast storm control globally:

Switch(config)# storm-control broadcast include multicast
Switch(config)# 

Related Commands

storm-control

switchport

To modify the switching characteristics of a Layer 2 switch interface, use the switchport command. To return the interface to the routed-interface status and cause all further Layer 2 configuration to be erased, use the no form of this command without parameters.

switchport [access vlan vlan_num] | [nonegotiate] | [voice vlan {vlan_id | dot1p | none | untagged}]

no switchport [access | nonegotiate | voice vlan]

Syntax Description

access vlan vlan_num

(Optional) Sets the VLAN when the interface is in access mode; valid values are from 1 to 1005.

nonegotiate

(Optional) Specifies that the DISL/DTP negotiation packets will not be sent on the interface.

voice vlan vlan_id

(Optional) Specifies the number of the VLAN; valid values are from 1 to 1005.

dot1p

(Optional) Specifies that the PVID packets are tagged as priority.

none

(Optional) Specifies that the telephone and voice VLAN do not communicate.

untagged

(Optional) Specifies the untagged PVID packets.


Defaults

The default settings are as follows:

Switchport trunking mode is enabled.

Dynamic negotiation parameter is set to auto.

Access VLANs and trunk interface native VLANs are a default VLAN corresponding to the platform or interface hardware.

All VLAN lists include all VLANs.

No voice VLAN is enabled.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.1(11)EW

Support for voice VLAN was added.


Usage Guidelines

The no switchport command shuts the port down and then reenables it, which may generate messages on the device to which the port is connected.

The no form of the switchport access command resets the access mode VLAN to the appropriate default VLAN for the device. The no form of the switchport nonegotiate command removes the nonegotiate status.

When you are using the nonegotiate keyword, DISL/DTP negotiation packets will not be sent on the interface. The device will trunk or not trunk according to the mode parameter given: access or trunk. This command will return an error if you attempt to execute it in dynamic (auto or desirable) mode.

The voice VLAN is automatically set to VLAN 1 unless you use one of the optional keywords.

If you use the switch port voice vlan command for an interface, the interface cannot join a port channel.

When you use the switchport voice vlan command, the output for the show running-config command changes to show the voice VLAN set.

Examples

This example shows how to cause the port interface to stop operating as a Cisco-routed port and convert to a Layer 2-switched interface:

Switch(config-if)# switchport
Switch(config-if)# 

This example shows how to cause a port interface in access mode, which is configured as a switched interface, to operate in VLAN 2:

Switch(config-if)# switchport access vlan 2
Switch(config-if)# 

This example shows how to cause a port interface, which is configured as a switched interface, to refrain from negotiating in trunking mode and act as a trunk or access port (depending on the mode set):

Switch(config-if)# switchport nonegotiate
Switch(config-if)# 

This example shows how to set the voice VLAN for the interface to VLAN 2:

Switch(config-if)# switchport voice vlan 2
switchport voice vlan 2
Switch(config-if)# 

Related Commands

show interfaces switchport

switchport access vlan

To set the VLAN when an interface is in access mode, use the switchport access vlan command. To reset the access mode VLAN to the appropriate default VLAN for the device, use the no form of this command.

switchport access [vlan {vlan-id | dynamic}]

no switchport access vlan

Syntax Description

vlan-id

(Optional) Number of the VLAN on the interface in access mode; valid values are from 1 to 4094.

dynamic

(Optional) Enables VMPS control of the VLAN.


Defaults

The default settings are as follows:

The access VLAN and trunk interface native VLAN are default VLANs that correspond to the platform or the interface hardware.

All VLAN lists include all VLANs.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.1(13)EW

Support for VPMS was added.


Usage Guidelines

You must enter the switchport command without any keywords to configure the LAN interface as a Layer 2 interface before you can enter the switchport access vlan command. This action is required only if you have not already entered the switchport command for the interface.

Entering the no switchport command shuts the port down and then reenables it, which could generate messages on the device to which the port is connected.

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

If your system is configured with a Supervisor Engine I, valid values for vlan-id are from 1 to 1005. If your system is configured with a Supervisor Engine II, valid values for vlan-id are from 1 to 4094. Extended-range VLANs are not supported on systems configured with a Supervisor Engine I.

Examples

This example shows how to cause the port interface to stop operating as a Cisco-routed port and convert to a Layer 2-switched interface:

Switch(config-if)# switchport
Switch(config-if)# 

Note This command is not used on platforms that do not support Cisco-routed ports. All physical ports on such platforms are assumed to be Layer 2-switched interfaces.


This example shows how to cause a port interface that has already been configured as a switched interface to operate in VLAN 2 instead of the platform's default VLAN when in access mode:

Switch(config-if)# switchport access vlan 2
Switch(config-if)# 

Related Commands

show interfaces switchport

switchport block

To prevent the unknown multicast or unicast packets from being forwarded, use the switchport block interface configuration command. To allow the unknown multicast or unicast packets to be forwarded, use the no form of this command.

switchport block {multicast | unicast}

no switchport block {multicast | unicast}

Syntax Description

multicast

Specifies that the unknown multicast traffic should be blocked.

unicast

Specifies that the unknown unicast traffic should be blocked.


Defaults

Unknown multicast and unicast traffic are not blocked.

All traffic with unknown MAC addresses is sent to all ports.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(19)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

You can block the unknown multicast or unicast traffic on the switch ports.

Blocking the unknown multicast or unicast traffic is not automatically enabled on the switch ports; you must explicitly configure it.


Note For more information about blocking the packets, refer to the software configuration guide for this release.


Examples

This example shows how to block the unknown multicast traffic on an interface:

Switch(config-if)# switchport block multicast

You can verify your setting by entering the show interfaces interface-id switchport privileged EXEC command.

Related Commands

show interfaces switchport

switchport mode

To set the interface type, use the switchport mode command. To reset the mode to the appropriate default mode for the device, use the no form of this command.

switchport mode {access | dot1q-tunnel | trunk | dynamic {auto | desirable}}

switchport mode private-vlan {host | promiscuous | trunk}

no switchport mode dot1q-tunnel

no switchport mode private-vlan

Syntax Description

access

Specifies a nontrunking, nontagged single VLAN Layer 2 interface.

dot1q-tunnel

Specifies an 802.1Q tunnel port.

trunk

Specifies a trunking VLAN Layer 2 interface.

dynamic auto

Specifies that the interface convert the link to a trunk link.

dynamic desirable

Specifies that the interface actively attempt to convert the link to a trunk link.

private-vlan host

Specifies that the ports with a valid PVLAN trunk association become active host private VLAN trunk ports.

private-vlan promiscuous

Specifies that the ports with a valid PVLAN mapping become active promiscuous ports.

private-vlan trunk

Specifies that the ports with a valid PVLAN trunk association become active host private VLAN trunk ports.


Defaults

Link converts to a trunk link.

dot1q tunnel ports are disabled.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.2(18)EW

Support was added for configuring dot1q tunnel ports.


Usage Guidelines

If you enter access mode, the interface goes into permanent nontrunking mode and negotiates to convert the link into a nontrunk link even if the neighboring interface does not approve the change.

If you enter trunk mode, the interface goes into permanent trunking mode and negotiates to convert the link into a trunk link even if the neighboring interface does not approve the change.

If you enter dynamic auto mode, the interface converts the link to a trunk link if the neighboring interface is set to trunk or desirable mode.

If you enter dynamic desirable mode, the interface becomes a trunk interface if the neighboring interface is set to trunk, desirable, or auto mode.

If you specify the dot1q-tunnel keyword, the port is set unconditionally as an 802.1Q tunnel port.

The port becomes inactive if you configure it as a private VLAN trunk port and one of the following applies:

The port does not have a valid PVLAN association.

The port does not have valid allowed normal VLANs.

If a private port PVLAN association or mapping is deleted, or if a private port is configured as a SPAN destination, it becomes inactive.

Examples

This example shows how to set the interface to dynamic desirable mode:

Switch(config-if)# switchport mode dynamic desirable
Switch(config-if)# 

This example shows how to set a port to PVLAN host mode:

Switch(config-if)# switchport mode private-vlan host
Switch(config-if)# 

This example shows how to set a port to private VLAN trunk:

Switch(config-if)# switchport mode private-vlan trunk
Switch(config-if)# 

This example shows how to configure a port for an 802.1Q tunnel port:

Switch(config-if)# switchport mode dot1q-tunnel 
Switch(config-if)# 

You can verify your settings by entering the show interfaces switchport command and examining information in the Administrative Mode and Operational Mode rows.

Related Commands

show interfaces switchport
switchport
switchport private-vlan host-association
switchport private-vlan mapping

switchport port-security

To enable port security on an interface, use the switchport port-security command. To disable port security and set parameters to their default states, use the no form of this command.

switchport port-security [aging {static | time time | type {absolute | inactivity}} |
limit rate invalid-source-mac [N | none] | mac-address mac-address | mac-address sticky [mac-address] | maximum value | violation {restrict | shutdown}]

no switchport port-security [aging {static | time time | type {absolute | inactivity}} |
limit rate invalid-source-mac [N | none] | mac-address mac-address | mac-address sticky [mac-address] | maximum value | violation {restrict | shutdown}]

Syntax Description

aging

(Optional) Specifies aging for port security.

static

(Optional) Enables aging for statically configured secure addresses on this port.

time time

(Optional) Specifies the aging time for this port. The valid values are from 0 to 1440 minutes. If the time is 0, aging is disabled for this port.

type absolute

(Optional) Sets the aging type as absolute aging. All the secure addresses on this port age out exactly after the time (minutes) specified and are removed from the secure address list.

type inactivity

(Optional) Sets the aging type as inactivity aging. The secure addresses on this port age out only if there is no data traffic from the secure source address for the specified time period.

limit rate invalid-source-mac

(Optional) Sets the rate limit for bad packets. This rate limit also applies to the port where DHCP snooping security mode is enabled as filtering the IP and MAC address.

N none

(Optional) Supplies a rate limit (N) or indicates none (none).

mac-address mac-address

(Optional) Specifies a secure MAC address for the interface; a 48-bit MAC address. You can add additional secure MAC addresses up to the maximum value that is configured.

sticky

(Optional) Configures the dynamic addresses as sticky on the interface.

maximum value

(Optional) Sets the maximum number of secure MAC addresses for the interface. Valid values are from 1 to 3072. The default setting is 1.

violation

(Optional) Sets the security violation mode and action to be taken if port security is violated.

restrict

(Optional) Sets the security violation restrict mode. In this mode, a port security violation restricts data and causes the security violation counter to increment.

shutdown

(Optional) Sets the security violation shutdown mode. In this mode, a port security violation causes the interface to immediately become error disabled.


Defaults

The default settings are as follows:

Port security is disabled.

When port security is enabled and no keywords are entered, the default maximum number of secure MAC addresses is 1.

Aging is disabled.

Aging time is 0 minutes.

All secure addresses on this port age out immediately after they are removed from the secure address list.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(13)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.1(19)EW

Extended to include DHCP snooping security enhancement.

12.2(18)EW

Add support for sticky interfaces.


Usage Guidelines

After you set the maximum number of secure MAC addresses that are allowed on a port, you can add secure addresses to the address table by manually configuring them, by allowing the port to dynamically configure them, or by configuring some MAC addresses and allowing the rest to be dynamically configured.

The packets are dropped into the hardware when the maximum number of secure MAC addresses are in the address table and a station that does not have a MAC address in the address table attempts to access the interface.

If you enable port security on a voice VLAN port and if there is a PC connected to the IP phone, you set the maximum allowed secure addresses on the port to more than 1.

You cannot configure static secure MAC addresses in the voice VLAN.

A secure port has the following limitations:

A secure port cannot be a dynamic access port or a trunk port.

A secure port cannot be a routed port.

A secure port cannot be a protected port.

A secure port cannot be a destination port for Switched Port Analyzer (SPAN).

A secure port cannot belong to a Fast EtherChannel or Gigabit EtherChannel port group.

A secure port cannot be an 802.1X port.

If you try to enable 802.1X on a secure port, an error message appears, and 802.1X is not enabled. If you try to change an 802.1X-enabled port to a secure port, an error message appears, and the security settings are not changed.

When a secure port is in the error-disabled state, you can remove it from this state by entering the errdisable recovery cause psecure-violation global configuration command, or you can manually reenable it by entering the shutdown and no shut down interface configuration commands.

To enable secure address aging for a particular port, set the aging time to a value other than 0 for that port.

To allow limited time access to particular secure addresses, set the aging type as absolute. When the aging time lapses, the secure addresses are deleted.

To allow continuous access to a limited number of secure addresses, set the aging type as inactivity. This action removes the secure address when it becomes inactive, and other addresses can become secure.

To allow unlimited access to a secure address, configure it as a secure address, and disable aging for the statically configured secure address by using the no switchport port-security aging static interface configuration command.

If the sticky command is executed without a MAC address specified, all MAC addresses that are learned on that port will be made sticky. You can also specify a specific MAC address to be a sticky address by entering the sticky keyword next to it.

You can configure the sticky feature even when port security is not enabled on the interface. The feature becomes operational when you enable port security on the interface.

You can use the no form of the sticky command only if the sticky feature is already enabled on the interface.

Examples

This example shows how to enable port security on Fast Ethernet port 12 and to set the maximum number of secure addresses to 5. The violation mode is the default, and no secure MAC addresses are configured.

Switch(config)# interface fastethernet 2/12
Switch(config-if)# switchport mode access
Switch(config-if)# switchport port-security
Switch(config-if)# switchport port-security maximum 5
Switch(config-if)#

You can verify the settings for all secure ports or the specified port by using the show port-security privileged EXEC command.

This example shows how to make all MAC addresses learned on Fast Ethernet port 12 sticky:

Switch(config)# interface fastethernet 2/12
SSwitch(config-if)# switchport port-security mac-address sticky
Switch(config-if)

This example shows how to make MAC address 1000.2000.3000 sticky on Fast Ethernet port 12:

Switch(config)# interface fastethernet 2/12
SSwitch(config-if)# switchport port-security mac-address sticky 1000.2000.3000
Switch(config-if)

This example shows how to disable the sticky feature on Fast Ethernet port 12:

Switch(config)# interface fastethernet 2/12
Switch(config-if)# no switchport port-security mac-address sticky
Switch(config-if)

Note This command makes all sticky addresses on this interface normal learned entries. It does not delete the entries from the secure MAC address table.


This example shows how to remove all sticky and static addresses that are configured on the interface:

Switch(config)# interface fastethernet 2/12
Switch(config-if)# no switchport port-security mac-address
Switch(config-if)

This example shows how to configure a secure MAC address on Fast Ethernet port 12:

Switch(config)# interface fastethernet 0/12
Switch(config-if)# switchport mode access
Switch(config-if)# switchport port-security
Switch(config-if)# switchport port-security mac-address 1000.2000.3000
Switch(config-if)

You can verify your settings by using the show port-security address privileged EXEC command.

Related Commands

show interfaces switchport
show port-security
switchport block

switchport private-vlan association trunk

To configure the association between a secondary VLAN and a VLAN on a private VLAN trunk port, use the switchport private-vlan association trunk command. To remove the private VLAN mapping from the port, use the no form of this command.

switchport private-vlan association trunk {primary-vlan-id} {secondary-vlan-id}

no switchport private-vlan association trunk {primary-vlan-id}

Syntax Description

primary-vlan-id

Number of the primary VLAN of the private VLAN relationship.

secondary-vlan-id

Number of the secondary VLAN of the private VLAN relationship.


Defaults

Private VLAN mapping is disabled.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.2(20)EW

Support for community VLAN was added.


Usage Guidelines

Multiple private VLAN pairs can be specified so that a private VLAN trunk port can carry multiple secondary VLANs. If an association is specified for the existing primary VLAN, the existing association is replaced.

Only isolated secondary VLANs can be carried over a private VLAN trunk.


Note Community secondary VLANs on a private VLAN trunk are not supported in this release.


If there is no trunk association, any packets received on the secondary VLANs are dropped.

Examples

This example shows how to configure a port with a primary VLAN (VLAN 18) and secondary VLAN (VLAN 20):

Switch(config-if)# switchport private-vlan association trunk 18 20
Switch(config-if)# 

This example shows how to remove the private VLAN association from the port:

Switch(config-if)# no switchport private-vlan association trunk 18
Switch(config-if)# 

Related Commands

show interfaces switchport
switchport mode

switchport private-vlan host-association

To define a PVLAN association for an isolated or community port, use the switchport private-vlan host-association command. To remove the PVLAN mapping from the port, use the no form of this command.

switchport private-vlan host-association {primary-vlan-id} {secondary-vlan-id}

no switchport private-vlan host-association

Syntax Description

primary-vlan-id

Number of the primary VLAN of the PVLAN relationship; valid values are from 1 to 4094.

secondary-vlan-list

Number of the secondary VLAN of the private VLAN relationship; valid values are from 1 to 4094.


Defaults

Private VLAN mapping is disabled.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.1(12c)EW

Support for extended addressing was added.


Usage Guidelines

There is no runtime effect on the port unless it is in PVLAN host mode. If the port is in PVLAN host mode but all VLANs do not exist, the command is allowed, but the port is made inactive.

The secondary VLAN may be an isolated or community VLAN.

Examples

This example shows how to configure a port with a primary VLAN (VLAN 18) and secondary VLAN (VLAN 20):

Switch(config-if)# switchport private-vlan host-association 18 20
Switch(config-if)# 

This example shows how to remove the PVLAN association from the port:

Switch(config-if)# no switchport private-vlan host-association
Switch(config-if)# 

Related Commands

show interfaces switchport
switchport mode

switchport private-vlan mapping

To define private VLAN mapping for a promiscuous port, use the switchport private-vlan mapping command. To clear all mapping from the primary VLAN, use the no form of this command.

switchport private-vlan mapping {primary-vlan-id} {secondary-vlan-list} | {add secondary-vlan-list} | {remove secondary-vlan-list}

no switchport private-vlan mapping

Syntax Description

primary-vlan-id

Number of the primary VLAN of the private VLAN relationship; valid values are from 2 to 4094 (excluding 1002 to 1005).

secondary-vlan-list

Number of the secondary VLANs to map to the primary VLAN; valid values are from 2 to 4094.

add

Maps the secondary VLANs to the primary VLAN.

remove

Clears mapping between the secondary VLANs and the primary VLAN.


Defaults

Private VLAN mapping is disabled.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.1(12c)EW

Support for extended addressing was added.

12.2(20)EW

Support for community VLAN was added.


Usage Guidelines

There is no run-time effect on the port unless it is in private VLAN promiscuous mode. If the port is in private VLAN promiscuous mode but the VLANs do not exist, the command is allowed, but the port is made inactive.

The secondary VLAN may be an isolated or community VLAN.

Examples

This example shows how to configure the mapping of primary VLAN 18 to the secondary isolated VLAN 20 on a port:

Switch(config-if)# switchport private-vlan mapping 18 20
Switch(config-if)# 

This example shows how to add a VLAN to the mapping:

Switch(config-if)# switchport private-vlan mapping 18 add 21
Switch(config-if)# 

This example shows how to add a range of secondary VLANs to the mapping:

Switch(config-if)# switchport private-vlan mapping 18 add 22-24
Switch(config-if)#

Related Commands

show interfaces private-vlan mapping

switchport private-vlan trunk allowed vlan

To configure a list of the allowed normal VLANs on a private VLAN trunk port, use the switchport private-vlan trunk allowed vlan command. To remove all the allowed normal VLANs from a private VLAN trunk port, use the no form of this command.

switchport private-vlan trunk allowed vlan {vlan-list} all | none | [add | remove | except] vlan_atom [,vlan_atom...]

no switchport private-vlan trunk allowed vlan

Syntax Description

vlan_list

Sets the list of allowed VLANs; see the "Usage Guidelines" section for formatting guidelines for vlan_list.

all

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

none

Indicates an empty list. This keyword is not supported on commands that require certain VLANs to be set or at least one VLAN to be set.

add

(Optional) Adds the defined list of VLANs to those currently set instead of replacing the list.

remove

(Optional) Removes the defined list of VLANs from those currently set instead of replacing the list.

except

(Optional) Lists the VLANs that should be calculated by inverting the defined list of VLANs.

vlan_atom

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.


Defaults

All allowed normal VLANs are removed from a private VLAN trunk port.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

By default, no normal VLANs are allowed unless you explicitly configure the VLANs to be allowed.

Use this command only for normal VLANs on a private VLAN trunk port.

Use the switchport private-vlan association trunk command to configure a port that can carry private VLANs on a private VLAN trunk port.

Examples

This example shows how to configure the private VLAN trunk port that carries normal VLANs 1 to10:

Switch(config-if)# switchport private-vlan trunk allowed vlan 1-10
Switch(config-if)# 

This example shows how to remove all the allowed normal VLANs from a private VLAN trunk port:

Switch(config-if)# no switchport private-vlan trunk allowed vlan
Switch(config-if)# 

Related Commands

show interfaces switchport
switchport mode

switchport private-vlan trunk native vlan tag

To control the tagging of the native VLAN traffic on 802.1Q private VLAN trunks, use the switchport private-vlan trunk native vlan tag command. To remove the control of tagging (and default to the global setting), use the no form of this command.

switchport private-vlan trunk native vlan tag

no switchport private-vlan trunk native vlan tag

Syntax Description

This command has no arguments or keywords.

Defaults

The default setting is global; the settings on the port are determined by the global setting.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.2(18)EW

Removed vlan-id keyword.


Usage Guidelines

The configuration created with this command only applies to ports that are configured as private VLAN trunks.

Examples

This example shows how to enable 802.1Q native VLAN tagging on a PVLAN trunk:

Switch(config-if)# switchport private-vlan trunk native vlan tag
Switch(config-if)# 

Related Commands

show interfaces switchport
switchport mode

switchport trunk

To set the trunk characteristics when an interface is in trunking mode, use the switchport trunk command. To reset all of the trunking characteristics back to the original defaults, use the no form of this command.

switchport trunk encapsulation {isl | dot1q | negotiate}

no switchport trunk encapsulation

switchport trunk native vlan {tag | vlan_id}

no switchport trunk native vlan {tag | vlan_id}

switchport trunk allowed vlan vlan_list

no switchport trunk allowed vlan vlan_list

switchport trunk pruning vlan vlan_list

no switchport trunk pruning vlan vlan_list

Syntax Description

encapsulation isl

Sets the trunk encapsulation format to ISL.

encapsulation dot1q

Sets the trunk encapsulation format to 802.1Q.

encapsulation negotiate

Specifies that if DISL and DTP negotiation do not resolve the encapsulation format, ISL will be the selected format.

native vlan tag

Specifies the tagging of native VLAN traffic on 802.1Q trunks.

native vlan vlan_id

Sets the native VLAN for the trunk in 802.1Q trunking mode.

allowed vlan vlan_list

Sets the list of allowed VLANs that transmit this interface in tagged format when in trunking mode. See the "Usage Guidelines" section for formatting guidelines for vlan_list.

pruning vlan vlan_list

Sets the list of VLANs that are enabled for VTP pruning when the switch is in trunking mode. See the "Usage Guidelines" section for formatting guidelines for vlan_list.


Defaults

The default settings are as follows:

The encapsulation type is dependent on the platform or interface hardware.

The access VLANs and trunk interface native VLANs are a default VLAN that corresponds to the platform or the interface hardware.

All VLAN lists include all VLANs.

Native VLAN tagging is enabled on the port if enabled globally.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.

12.1(12c)EW

Support for extended addressing was added.

12.2(18)EW

Support for native VLAN tagging was added.


Usage Guidelines

The vlan_list format is all | none | [add | remove | except] vlan_atom[,vlan_atom...], where:

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

none indicates an empty list. This keyword is not supported 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.

remove removes the defined list of VLANs from those currently set, instead of replacing the list.

except lists the VLANs that should be calculated by inverting the defined list of VLANs.

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).

The switchport trunk encapsulation command is supported only for platforms and interface hardware that can support both ISL and 802.1Q formats.

If you enter the negotiate keywords, and DISL and DTP negotiation do not resolve the encapsulation format, ISL is the selected format. The no form of this command resets the trunk encapsulation format back to the default.

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

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

The no form of the pruning vlan command resets the list to the default list, which enables all VLANs for VTP pruning.

These configuration guidelines and restrictions apply when using 802.1Q trunks and impose some limitations on the trunking strategy for a network:

When connecting Cisco switches through an 802.1Q trunk, make sure that the native VLAN for an 802.1Q trunk is the same on both ends of the trunk link. If the native VLAN on one end of the trunk is different from the native VLAN on the other end, spanning-tree loops might result.

Disabling spanning tree on the native VLAN of an 802.1Q trunk without disabling spanning tree on every VLAN in the network can cause spanning-tree loops. We recommend that you leave spanning tree enabled on the native VLAN of an 802.1Q trunk. If this is not possible, disable spanning tree on every VLAN in the network. Make sure that your network is free of physical loops before disabling spanning tree.

When you connect two Cisco switches through 802.1Q trunks, the switches exchange spanning-tree BPDUs on each VLAN that is allowed on the trunks. The BPDUs on the native VLAN of the trunk are sent untagged to the reserved 802.1d spanning-tree multicast MAC address (01-80-C2-00-00-00). The BPDUs on all other VLANs on the trunk are sent tagged to the reserved SSTP multicast MAC address (01-00-0c-cc-cc-cd).

Non-Cisco 802.1Q switches maintain only a single instance of spanning tree (MST) that defines the spanning-tree topology for all VLANs. When you connect a Cisco switch to a non-Cisco switch through an 802.1Q trunk, the MST of the non-Cisco switch and the native VLAN spanning tree of the Cisco switch combine to form a single spanning-tree topology known as the CST.

Because Cisco switches transmit BPDUs to the SSTP multicast MAC address on the VLANs other than the native VLAN of the trunk, non-Cisco switches do not recognize these frames as BPDUs and flood them on all ports in the corresponding VLAN. Cisco switches connected to the non-Cisco 802.1Q network receive these flooded BPDUs. Because Cisco switches receive the flooded BPDUs, the switches can maintain a per-VLAN spanning-tree topology across a network of non-Cisco 802.1Q switches. The non-Cisco 802.1Q network separating the Cisco switches is treated as a single broadcast segment between all switches that are connected to the non-Cisco 802.1Q network through the 802.1Q trunks.

Ensure that the native VLAN is the same on all of the 802.1Q trunks connecting the Cisco switches to the non-Cisco 802.1Q network.

If you are connecting multiple Cisco switches to a non-Cisco 802.1Q network, all of the connections must be through the 802.1Q trunks. You cannot connect Cisco switches to a non-Cisco 802.1Q network through the ISL trunks or through the access ports. This action causes the switch to place the ISL trunk port or access port into the spanning-tree "port inconsistent" state and no traffic will pass through the port.

Follow these guidelines for native VLAN tagging:

The no switchport trunk native vlan tag command disables the native VLAN tagging operation on a port. This overrides the global tagging configuration.

The switchport trunk native vlan tag command can be used to reenable tagging on a disabled port.

The no option is saved to NVRAM so that the user does not have to manually select the ports to disable the tagging operation each time that the switch reboots.

When the switchport trunk native vlan tag command is enabled and active, all packets on the native VLAN are tagged, and incoming untagged data packets are dropped. Untagged control packets are accepted.

Examples

This example shows how to cause a port interface that is configured as a switched interface to encapsulate in 802.1Q trunking format regardless of its default trunking format in trunking mode:

Switch(config-if)# switchport trunk encapsulation dot1q
Switch(config-if)# 

This example shows how to enable 802.1Q tagging on a port:

Switch(config-if)# switchport trunk native vlan tag
Switch(config-if)# 

Related Commands

show interfaces switchport

system mtu

To set the maximum Layer 2 or Layer 3 payload size, use the system mtu command. To revert to the default MTU setting, use the no form of this command.

system mtu datagram-size

no system mtu

Syntax Description

datagram-size

Layer 2 payload size; valid values from 1500 to 1552 bytes.


Defaults

The default MTU setting is 1500 bytes.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

The datagram-size parameter specifies the Ethernet payload size, not the total Ethernet frame size, and the Layer 3 MTU is changed as a result of changing the system mtu command.

For ports from 3 to18 on model WS-X4418-GB and ports from 1 to 12 on model WS-X4412-2GB-TX, only the standard IEEE Ethernet payload size of 1500 bytes is supported.

For other modules, an Ethernet payload size of up to 1552 bytes is supported with a total Ethernet frame size of up to 1600 bytes.

Examples

This example shows how to set the MTU size to 1550 bytes:

Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# system mtu 1550
Switch(config)# end
Switch# 

This example shows how to revert to the default MTU setting:

Switch# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# no system mtu
Switch(config)# end
Switch# 

Related Commands

show interfaces
show system mtu

traceroute mac

To display the Layer 2 path taken by the packets from the specified source MAC address to the specified destination MAC address, use the traceroute mac command.

traceroute mac [interface interface-id] {source-mac-address} [interface interface-id] {destination-mac-address} [vlan vlan-id] [detail]

Syntax Description

interface interface-id

(Optional) Specifies the source or destination switch interface.

source-mac-address

MAC address of the source switch in hexadecimal format.

destination-mac-address

MAC address of the destination switch in hexadecimal format.

vlan vlan-id

(Optional) Specifies the VLAN on which to trace the Layer 2 path that the packets take from the source switch to the destination switch; valid VLAN IDs are from 1 to 4094. Do not enter leading zeros.

detail

(Optional) Displays detail information.


Defaults

This command has no default settings.

Command Modes

Privileged EXEC

Command History

Release
Modification

12.1(15)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

Do not use leading zeros when entering a VLAN ID.

The Layer 2 traceroute feature is available on these switches:

Catalyst 2950 switches running Release 12.1(12c)EA1 or later

Catalyst 3550 switches running Release 12.1(12c)EA1 or later

Catalyst 4500 series switches running Catalyst operating system Release 6.2 or later for the supervisor engine

Catalyst 4500 series switches running Release 12.1(15)EW or later

Catalyst 5000 family switches running Catalyst operating system Release 6.1 or later for the supervisor engine

Catalyst 6500 series switches running Catalyst operating system Release 6.1 or later for the supervisor engine

For Layer 2 traceroute to functional properly, Cisco Discovery Protocol (CDP) must be enabled on all of the switches in the network. Do not disable CDP.

When the switch detects a device in the Layer 2 path that does not support Layer 2 traceroute, the switch continues to send Layer 2 trace queries and lets them time out.

The maximum number of hops identified in the path is ten.

Layer 2 traceroute supports only unicast traffic. If you specify a multicast source or destination MAC address, the physical path is not identified, and a message appears.

The traceroute mac command output shows the Layer 2 path when the specified source and destination addresses belong to the same VLAN. If you specify source and destination addresses that belong to different VLANs, the Layer 2 path is not identified, and a message appears.

If the source or destination MAC address belongs to multiple VLANs, you must specify the VLAN to which both the source and destination MAC addresses belong. If the VLAN is not specified, the path is not identified, and a message appears.

Layer 2 traceroute is not supported when multiple devices are attached to one port through hubs (for example, multiple CDP neighbors are detected on a port). When more than one CDP neighbor is detected on a port, the Layer 2 path is not identified, and a message appears.

This feature is not supported in Token Ring VLANs.

Examples

This example shows how to display the Layer 2 path by specifying the source and destination MAC addresses:

Switch# traceroute mac 0000.0201.0601 0000.0201.0201

Source 0000.0201.0601 found on con6[WS-C2950G-24-EI] (2.2.6.6)
con6 (2.2.6.6) :Fa0/1 =>Fa0/3
con5                 (2.2.5.5        )  :    Fa0/3 =>Gi0/1
con1                 (2.2.1.1        )  :    Gi0/1 =>Gi0/2
con2                 (2.2.2.2        )  :    Gi0/2 =>Fa0/1
Destination 0000.0201.0201 found on con2[WS-C3550-24] (2.2.2.2)
Layer 2 trace completed
Switch# 

This example shows how to display the detailed Layer 2 path:

Switch# traceroute mac 0000.0201.0601 0000.0201.0201 detail
Source 0000.0201.0601 found on con6[WS-C2950G-24-EI] (2.2.6.6)
con6 / WS-C2950G-24-EI / 2.2.6.6 :
        Fa0/1 [auto, auto] =>Fa0/3 [auto, auto]
con5 / WS-C2950G-24-EI / 2.2.5.5 :
        Fa0/3 [auto, auto] =>Gi0/1 [auto, auto]
con1 / WS-C3550-12G / 2.2.1.1 :
        Gi0/1 [auto, auto] =>Gi0/2 [auto, auto]
con2 / WS-C3550-24 / 2.2.2.2 :
        Gi0/2 [auto, auto] =>Fa0/1 [auto, auto]
Destination 0000.0201.0201 found on con2[WS-C3550-24] (2.2.2.2)
Layer 2 trace completed.
Switch# 

This example shows the Layer 2 path when the switch is not connected to the source switch:

Switch# traceroute mac 0000.0201.0501 0000.0201.0201 detail
Source not directly connected, tracing source .....
Source 0000.0201.0501 found on con5[WS-C2950G-24-EI] (2.2.5.5)
con5 / WS-C2950G-24-EI / 2.2.5.5 :
        Fa0/1 [auto, auto] =>Gi0/1 [auto, auto]
con1 / WS-C3550-12G / 2.2.1.1 :
        Gi0/1 [auto, auto] =>Gi0/2 [auto, auto]
con2 / WS-C3550-24 / 2.2.2.2 :
        Gi0/2 [auto, auto] =>Fa0/1 [auto, auto]
Destination 0000.0201.0201 found on con2[WS-C3550-24] (2.2.2.2)
Layer 2 trace completed.
Switch# 

This example shows the Layer 2 path when the switch cannot find the destination port for the source MAC address:

Switch# traceroute mac 0000.0011.1111 0000.0201.0201
Error:Source Mac address not found. 
Layer2 trace aborted.
Switch# 

This example shows the Layer 2 path when the source and destination devices are in different VLANs:

Switch# traceroute mac 0000.0201.0601 0000.0301.0201
Error:Source and destination macs are on different vlans. 
Layer2 trace aborted.
Switch# 

This example shows the Layer 2 path when the destination MAC address is a multicast address:

Switch# traceroute mac 0000.0201.0601 0100.0201.0201
Invalid destination mac address
Switch# 

This example shows the Layer 2 path when the source and destination switches belong to multiple VLANs:

Switch# traceroute mac 0000.0201.0601 0000.0201.0201
Error:Mac found on multiple vlans.
Layer2 trace aborted.
Switch# 

This example shows how to display the Layer 2 path by specifying the interfaces on the source and destination switches:

Switch# traceroute mac interface fastethernet0/1 0000.0201.0601 interface fastethernet0/3 0000.0201.0201
Source 0000.0201.0601 found on con6[WS-C2950G-24-EI] (2.2.6.6)
con6 (2.2.6.6) :Fa0/1 =>Fa0/3
con5                 (2.2.5.5        )  :    Fa0/3 =>Gi0/1
con1                 (2.2.1.1        )  :    Gi0/1 =>Gi0/2
con2                 (2.2.2.2        )  :    Gi0/2 =>Fa0/1
Destination 0000.0201.0201 found on con2[WS-C3550-24] (2.2.2.2)
Layer 2 trace completed
Switch# 

Related Commands

traceroute mac ip

traceroute mac ip

To display the Layer 2 path that is taken by the packets from the specified source IP address or hostname to the specified destination IP address or hostname, use the traceroute mac command.

traceroute mac ip {source-ip-address | source-hostname} {destination-ip-address | destination-hostname} [detail]

Syntax Description

source-ip-address

IP address of the source switch as a 32-bit quantity in dotted-decimal format.

destination-ip-address

IP address of the destination switch as a 32-bit quantity in dotted-decimal format.

source-hostname

IP hostname of the source switch.

destination-hostname

IP hostname of the destination switch.

detail

(Optional) Displays detailed traceroute MAC IP information.


Defaults

This command has no default settings.

Command Modes

Privileged EXEC

Command History

Release
Modification

12.1(13)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

The Layer 2 traceroute feature is available on these switches:

Catalyst 2950 switches running Release 12.1(12c)EA1 or later

Catalyst 3550 switches running Release 12.1(12c)EA1 or later

Catalyst 4500 series switches running Catalyst operating system Release 6.2 or later for the supervisor engine

Catalyst 4500 series switches running Release 12.1(15)EW or later

Catalyst 5000 family switches running Catalyst operating system Release 6.1 or later for the supervisor engine

Catalyst 6500 series switches running Catalyst operating system Release 6.1 or later for the supervisor engine

For Layer 2 traceroute to functional properly, Cisco Discovery Protocol (CDP) must be enabled on all the switches in the network. Do not disable CDP.

When the switch detects a device in the Layer 2 path that does not support Layer 2 traceroute, the switch continues to send Layer 2 trace queries and lets them time out.

The maximum number of hops identified in the path is ten.

The traceroute mac ip command output shows the Layer 2 path when the specified source and destination IP addresses are in the same subnet. When you specify the IP addresses, the switch uses Address Resolution Protocol (ARP) to associate the IP addresses with the corresponding MAC addresses and the VLAN IDs.

If an ARP entry exists for the specified IP address, the switch uses the associated MAC address and identifies the physical path.

If an ARP entry does not exist, the switch sends an ARP query and tries to resolve the IP address. The IP addresses must be in the same subnet. If the IP address is not resolved, the path is not identified, and a message appears.

Layer 2 traceroute is not supported when multiple devices are attached to one port through hubs (for example, multiple CDP neighbors are detected on a port). When more than one CDP neighbor is detected on a port, the Layer 2 path is not identified, and an error message appears.

This feature is not supported in Token Ring VLANs.

Examples

This example shows how to display the Layer 2 path by specifying the source and destination IP addresses and by using the detail keyword:

Switch# traceroute mac ip 2.2.66.66 2.2.22.22 detail
Translating IP to mac..... 
2.2.66.66 =>0000.0201.0601
2.2.22.22 =>0000.0201.0201

Source 0000.0201.0601 found on con6[WS-C2950G-24-EI] (2.2.6.6)
con6 / WS-C2950G-24-EI / 2.2.6.6 :
        Fa0/1 [auto, auto] =>Fa0/3 [auto, auto]
con5 / WS-C2950G-24-EI / 2.2.5.5 :
        Fa0/3 [auto, auto] =>Gi0/1 [auto, auto]
con1 / WS-C3550-12G / 2.2.1.1 :
        Gi0/1 [auto, auto] =>Gi0/2 [auto, auto]
con2 / WS-C3550-24 / 2.2.2.2 :
        Gi0/2 [auto, auto] =>Fa0/1 [auto, auto]
Destination 0000.0201.0201 found on con2[WS-C3550-24] (2.2.2.2)
Layer 2 trace completed.
Switch# 

This example shows how to display the Layer 2 path by specifying the source and destination hostnames:

Switch# traceroute mac ip con6 con2
Translating IP to mac ..... 
2.2.66.66 =>0000.0201.0601
2.2.22.22 =>0000.0201.0201

Source 0000.0201.0601 found on con6
con6 (2.2.6.6) :Fa0/1 =>Fa0/3
con5                 (2.2.5.5        )  :    Fa0/3 =>Gi0/1
con1                 (2.2.1.1        )  :    Gi0/1 =>Gi0/2
con2                 (2.2.2.2        )  :    Gi0/2 =>Fa0/1
Destination 0000.0201.0201 found on con2
Layer 2 trace completed
Switch# 

This example shows the Layer 2 path when Address Resolution Protocol (ARP) cannot associate the source IP address with the corresponding MAC address:

Switch# traceroute mac ip 2.2.66.66 2.2.77.77
Arp failed for destination 2.2.77.77.
Layer2 trace aborted.
Switch# 

Related Commands

traceroute mac

tx-queue

To configure the transmit queue parameters for an interface, use the tx-queue command. To return to the default value, use the no form of this command.

tx-queue [queue-id] {bandwidth bandwidth-rate | priority high | shape shape-rate}

no tx-queue

Syntax Description

queue-id

(Optional) Number of the queue; valid values are from 1 to 4.

bandwidth bandwidth-rate

Specifies traffic bandwidth; valid values are from 16000 to 1000000000 bits per second.

priority high

Specifies high priority.

shape shape-rate

Specifies the maximum rate that packets are passed through a transmit queue; valid values are from 16000 to 1000000000 bits per second.


Defaults

The default settings are as follows:

Encapsulation type is dependent on the platform or interface hardware.

QoS enabled bandwidth rate is 4:255.

QoS disabled bandwidth rate is 255:1.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

The bandwidth and shape rates cannot exceed the maximum speed of the interface.

The bandwidth can be configured only on the following:

Uplink ports on Supervisor Engine III (WS-X4014)

Ports on the WS-X4306-GB module

The two 1000BASE-X ports on the WS-X4232-GB-RJ module

The first two ports on the WS-X4418-GB module

The two 1000BASE-X ports on the WS-X4412-2GB-TX module

Only transmit queue 3 can be configured to be a high-priority transmit queue.

Examples

This example shows how to allocate bandwidth on queue 1 to 100 Mbps:

Switch(config-if)# tx-queue 1 
Switch(config-if-tx-queue)# bandwidth 1000000000
Switch(config-if-tx-queue)# 

This example shows how to configure transmit queue 3 to the high priority:

Switch(config-if)# tx-queue 3 
Switch(config-if-tx-queue)# priority high
Switch(config-if-tx-queue)# 

This example shows how to configure the traffic shaping rate of 64 kbps to transmit queue 1:

Switch(config-if)# tx-queue 1 
Switch(config-if-tx-queue)# shape 64000
Switch(config-if-tx-queue)# 

Related Commands

show qos interface

udld (global configuration mode)

To enable aggressive or normal mode in the UDLD protocol and to set the configurable message timer time, use the udld command. Use the no form of this command to do the following:

Disable normal mode UDLD on all the fiber ports by default

Disable aggressive mode UDLD on all the fiber ports by default

Disable the message timer

udld enable | aggressive

no udld enable | aggressive

udld message time message-timer-time

no udld message time

Syntax Description

enable

Enables UDLD in normal mode by default on all the fiber interfaces.

aggressive

Enables UDLD in aggressive mode by default on all the fiber interfaces.

message time message-timer-time

Sets the period of time between the UDLD probe messages on the ports that are in advertisement mode and are currently determined to be bidirectional; valid values are from 7 to 90 seconds.


Defaults

All fiber interfaces are disabled and the message timer time equals 15 seconds.

Command Modes

Global configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

If you enable aggressive mode, once all the neighbors of a port have aged out either in the advertisement or in the detection phase, UDLD restarts the linkup sequence to try to resynchronize with any potentially out-of-sync neighbor and shuts down the port if the message train from the link is still undetermined.

This command affects the fiber interfaces only. Use the udld (interface configuration mode) command to enable UDLD on the other interface types.

Examples

This example shows how to enable UDLD on all the fiber interfaces:

Switch (config)# udld enable
Switch (config)# 

Related Commands

show udld
udld (interface configuration mode)

udld (interface configuration mode)

To enable UDLD on an individual interface or to prevent a fiber interface from being enabled by the udld (global configuration mode) command, use the udld command. To return to the udld (global configuration mode) command setting, or if the port is a nonfiber port to disable UDLD, use the no form of this command.

udld {enable | aggressive | disable}

no udld {enable | aggressive | disable}

Syntax Description

enable

Enables UDLD on this interface.

aggressive

Enables UDLD in aggressive mode on this interface.

disable

Disables UDLD on this interface.


Defaults

The fiber interfaces are enabled per the state of the global udld (enable or aggressive) command, and the nonfiber interfaces are enabled with UDLD disabled.

Command Modes

Interface configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

If you enable aggressive mode, once all the neighbors of a port have aged out either in the advertisement or in the detection phase, UDLD restarts the linkup sequence to try to resynchronize with any potentially out-of-sync neighbor and shuts down the port if the message train from the link is still undetermined.

Use the no udld enable command on the fiber ports to return control of UDLD to the global udld enable command or to disable UDLD on the nonfiber ports.

Use the udld aggressive command on the fiber ports to override the setting of the global udld (enable or aggressive) command. Use the no form on the fiber ports to remove this setting, return control of UDLD enabling back to the global udld command or to disable UDLD on the nonfiber ports.

The disable keyword is supported on the fiber ports only. Use the no form of this command to remove this setting and return control of UDLD to the udld (global configuration mode) command.

If the port changes from fiber to nonfiber or vice versa, all configurations will be maintained because of a change of module or a GBIC change detected by the platform software.

Examples

This example shows how to cause any port interface to enable UDLD, despite the current global udld (global configuration mode) setting:

Switch (config-if)# udld enable
Switch (config-if)# 

This example shows how to cause any port interface to enable UDLD in aggressive mode, despite the current global udld (enable or aggressive) setting:

Switch (config-if)# udld aggressive
Switch (config-if)# 

This example shows how to cause a fiber port interface to disable UDLD, despite the current global udld (global configuration mode) setting:

Switch (config-if)# udld disable
Switch (config-if)# 

Related Commands

show udld
udld (global configuration mode)


udld reset

To reset all the UDLD ports in the shutdown state, use the udld reset command.

udld reset

Syntax Description

This command has no keywords or variables.

Defaults

This command has no default settings.

Command Modes

Privileged EXEC

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

If the interface configuration is still enabled for UDLD, these ports will begin to run UDLD again and may shut down if the reason for the shutdown has not been corrected.

The udld reset command permits the traffic to flow on the ports again; other features, such as spanning tree, PAgP, and DTP, operate normally if enabled.

Examples

This example shows how to reset all the ports that are shut down by UDLD:

Switch# udld reset
Switch# 

Related Commands

show udld

unidirectional

To configure the nonblocking Gigabit Ethernet ports to unidirectionally send or receive traffic on an interface, use the unidirectional command. To disable unidirectional communication, use the no form of this command.

unidirectional {receive-only | send-only}

no unidirectional {receive-only | send-only}

Syntax Description

receive-only

Specifies the unidirectional reception.

send-only

Specifies the unidirectional transmission.


Defaults

Disabled

Command Modes

Interface configuration

Command History

Release
Modification

12.1(13)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

Enabling port unidirectional mode automatically disables port UDLD. You must manually ensure that the unidirectional link does not create a spanning-tree loop in the network.

Examples

This example shows how to set Gigabit Ethernet interface 1/1 to receive traffic unidirectionally:

Switch# config terminal 
Enter configuration commands, one per line. End with CNTL/Z.
Switch(config)# interface gigabitethernet 1/1 
Switch(config-if)# unidirectional receive-only
Switch(config-if)# end
Switch# 

Related Commands

show interfaces switchport

username

To establish a username-based authentication system, use the username command.

username name secret {0 | 5} password

Syntax Description

name

User ID of the user.

secret 0 | 5

Specifies the authentication system for the user; valid values are 0 (text immediately following is not encrypted) and 5 (text immediately following is encrypted using an MD5-type encryption method).

password

Password of the user.


Defaults

No username-based authentication system is established.

Command Modes

Global configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

Use this command to enable enhanced password security for the specified username. This command enables MD5 encryption on the password. MD5 encryption is a strong encryption method that is not retrievable. You cannot use MD5 encryption with protocols that require clear-text passwords, such as CHAP.

You can use this command for defining usernames that get special treatment. For example, you can define an "info" username that does not require a password but that connects the user to a general-purpose information service.

The username command provides both username and secret authentication for login purposes only.

The name argument can be only one word. White spaces and quotation marks are not allowed.

You can use multiple username commands to specify options for a single user.

For information about additional username commands, refer to the Cisco IOS Command Reference.

Examples

This example shows how to specify an MD5 encryption on a password (warrior) for a username (xena):

Switch(config)# username xena secret 5 warrior
Switch(config)# 

Related Commands

enable password (refer to Cisco IOS documentation)
enable secret (refer to Cisco IOS documentation)
username (refer to Cisco IOS documentation)

verify

To verify the checksum of a file on a Flash memory file system, use the verify command.

verify [/md5] [flash-filesystem:] [filename] [expected-md5-signature]

Syntax Description

/md5

(Optional) Verifies the MD5 signatures.

flash-filesystem:

(Optional) Device where the Flash resides; valid values are bootflash:, slot0:, flash:, or sup-bootflash:.

filename

(Optional) Name of the Cisco IOS image.

expected-md5-signature

(Optional) MD5 signature.


Defaults

The current working device is specified.

Command Modes

Privileged EXEC

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

Each software image that is distributed on the disk uses a single checksum for the entire image. This checksum is displayed only when the image is copied into the Flash memory.

The Readme file, which is included with the image on the disk, lists the name, file size, and checksum of the image. Review the contents of the Readme file before loading or duplicating the new image so that you can verify the checksum when you copy it into the Flash memory or on to a server.

Use the verify /md5 command to verify the MD5 signature of a file before using it. This command validates the integrity of a copied file by comparing a precomputed MD5 signature with the signature that is computed by this command. If the two MD5 signatures match, the copied file is identical to the original file.

You can find the MD5 signature posted on the Cisco.com page with the image.

You can use the verify /md5 command in one of the following ways:

Verify the MD5 signatures manually by entering the verify /md5 filename command.

Check the displayed signature against the MD5 signature posted on the Cisco.com page.

Allow the system to compare the MD5 signatures by entering the verify /md5 {flash-filesystem:filename} {expected-md5-signature} command.

After completing the comparison, the system returns with a verified message. If an error is detected, the output is similar to the following:

Switch# verify /md5 slot0:c4-jsv-mz 0f
 ..................................
 ..................................
 ..................................
 ..................................
 ..................................
 ...............................Done!
 %Error verifying slot0:c4-jsv-mz
 Computed signature  = 0f369ed9e98756f179d4f29d6e7755d3
 Submitted signature = 0f

To display the contents of the Flash memory, enter the show flash command. The Flash contents listing does not include the checksum of the individual files. To recompute and verify the image checksum after the image has been copied into the Flash memory, enter the verify command.

A colon (:) is required after the specified device.

Examples

This example shows how to use the verify command:

Switch# verify cat6k_r47_1.cbi
..........................................................
File cat6k_r47_1.cbi verified OK.
Switch# 

This example shows how to manually check the MD5 signature:

Switch# verify /md5 c4-jsv-mz
 .................................................
 .................................................
 .................................................
 .................................................
 .................................................
 ............................................Done!
 verify /md5 (slot0:c4-jsv-mz) = 0f369ed9e98756f179d4f29d6e7755d3 
Switch# 

This example shows how to allow the system to compare the MD5 signatures:

Switch# verify /md5 slot0:c4-jsv-mz 0f369ed9e98756f179d4f29d6e7755d3
 .................................................
 .................................................
 .................................................
 .................................................
 .................................................
 ............................................Done!
 verified /md5 (slot0:c6sup12-jsv-mz) = 0f369ed9e98756f179d4f29d6e7755d3
Switch# 

Related Commands

show file system (Flash file system) (refer to Cisco IOS documentation)
show flash (refer to Cisco IOS documentation)

vlan (VLAN Database mode)

To configure a specific VLAN, use the vlan command. To delete a VLAN, use the no form of this command.

vlan vlan_id [are hops] [backupcrf mode] [bridge type | bridge-num] [media type] [mtu mtu-size] [name vlan-name] [parent parent-vlan-id] [ring ring-number] [said said-value] [state {suspend | active}] [stp type type] [tb-vlan1 tb-vlan1-id] [tb-vlan2 tb-vlan2-id]

no vlan vlan

Syntax Description

vlan_id

Number of the VLAN; valid values are from 1 to 4094.

are hops

(Optional) Specifies the maximum number of All Route Explorer hops for this VLAN; valid values are from 0 to 13. Zero is assumed if no value is specified.

backupcrf mode

(Optional) Enables or disables the backup CRF mode of the VLAN; valid values are enable and disable.

bridge type

(Optional) Specifies the bridging characteristics of the VLAN or identification number of the bridge; valid type values are srb and srt.

bridge_num

(Optional) Valid bridge_num values are from 0 to 15.

media type

(Optional) Specifies the media type of the VLAN; valid values are fast ethernet, fd-net, fddi, trcrf, and trbrf.

mtu mtu-size

(Optional) Specifies the maximum transmission unit (packet size, in bytes) that the VLAN can use; valid values are from 576 to 18190.

name vlan-name

(Optional) Defines a text string used as the name of the VLAN (1 to 32 characters).

parent parent-vlan-id

(Optional) Specifies the ID number of the parent VLAN of FDDI or Token Ring-type VLANs; valid values are from 2 to 1001.

ring ring-number

(Optional) Specifies the ring number of FDDI or Token Ring-type VLANs; valid values are from 2 to 1001.

said said-value

(Optional) Specifies the security association identifier; valid values are from 1 to 4294967294.

state

(Optional) Specifies the state of the VLAN.

suspend

Specifies that the state of the VLAN is suspended. VLANs in the suspended state do not pass packets.

active

Specifies that the state of the VLAN is active.

stp type type

(Optional) Specifies the STP type; valid values are ieee, ibm, and auto.

tb-vlan1 tb-vlan1-id

(Optional) Specifies the ID number of the first translational VLAN for this VLAN; valid values are from 2 to 1001. Zero is assumed if no value is specified.

tb-vlan2 tb-vlan2-id

(Optional) Specifies the ID number of the second translational VLAN for this VLAN; valid values are from 2 to 1001. Zero is assumed if no value is specified.


Defaults

The defaults are as follows:

The vlan-name is "VLANxxxx" where "xxxx" represents four numeric digits (including leading zeroes) equal to the VLAN ID number.

The media type is Fast Ethernet.

The state is active.

The said-value is 100,000 plus the VLAN ID number.

The mtu-size default is dependent upon the VLAN type:

fddi—1500

trcrf—1500 if V2 is not enabled; 4472 if it is enabled

fd-net—1500

trbrf—1500 if V2 is not enabled; 4472 if it is enabled

No ring number is specified.

No bridge number is specified.

No parent VLAN is specified.

No STP type is specified.

No translational bridge VLAN is specified.

Command Modes

VLAN configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

VLAN 1 parameters are factory configured and cannot be changed.

When you define vlan-name, the name must be unique within the administrative domain.

The SAID is documented in 802.10. When the no form is used, the VLANs SAID is returned to the default.

When you define the said-value, the name must be unique within the administrative domain.

The bridge bridge-number argument is used only for Token Ring-net and FDDI-net VLANs and is ignored in other types of VLANs. When the no form is used, the VLANs source-route bridging number returns to the default.

The parent VLAN resets to the default if the parent VLAN is deleted or the media keyword changes the VLAN type or the VLAN type of the parent VLAN.

The tb-vlan1 and tb-vlan2 are used to configure translational bridge VLANs of a specified type of VLAN and are not allowed in other types of VLANs. The translational bridge VLANs must be a different VLAN type than the affected VLAN; if two VLANs are specified, the two must be different VLAN types.

A translational bridge VLAN will reset to the default if the translational bridge VLAN is deleted or the media keyword changes the VLAN type or the VLAN type of the corresponding translational bridge VLAN.

Examples

This example shows how to add a new VLAN with all the default parameters to the new VLAN database:

Switch(vlan)# vlan 2


Note If the VLAN already exists, no action occurs.


This example shows how to cause the device to add a new VLAN, specify the media type and parent VLAN ID number 3, and set all the other parameters to the defaults:

Switch(vlan)# vlan 2 media fastethernet parent 3
VLAN 2 modified:
    Media type FASTETHERNET
    Parent VLAN 3

This example shows how to delete VLAN 2:

Switch(vlan)# no vlan 2
Switch(vlan)# 

This example shows how to return the MTU to the default for its type and the translational bridging VLANs to the default:

Switch(vlan)# no vlan 2 mtu tb-vlan1 tb-vlan2
Switch(vlan)# 

Related Commands

show vlan

vlan access-map

To enter VLAN access-map command mode to create a VLAN access map, use the vlan access-map command. To remove a mapping sequence or the entire map, use the no form of this command.

vlan access-map name [seq# ]

no vlan access-map name [seq# ]

Syntax Description

name

VLAN access-map tag.

seq#

(Optional) Map sequence number; valid values are from 0 to 65535.


Defaults

This command has no default settings.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

If you enter the sequence number of an existing map sequence, you enter VLAN access-map mode. If you do not specify a sequence number, a number is automatically assigned. You can enter one match clause and one action clause per map sequence. If you enter the no vlan access-map name [seq# ] command without entering a sequence number, the whole map is removed. Once you enter VLAN access-map mode, the following commands are available:

actionSets the action to be taken (forward or drop).

defaultReturns a command to its default settings.

endExits from configuration mode.

exitExits from VLAN access-map configuration mode.

matchSets the values to match (IP address or MAC address).

noNegates a command or reset its defaults.

Examples

This example shows how to enter VLAN access-map mode:

Switch(config)# vlan access-map cisco
Switch(config-access-map)# 

Related Commands

match
show vlan access-map

vlan database

To enter VLAN configuration mode, use the vlan database command.

vlan database

Syntax Description

This command has no arguments or keywords.

Defaults

This command has no default settings.

Command Modes

Privileged EXEC

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

From VLAN configuration mode, you can access the VLAN database editing buffer manipulation commands, including:

abort—Exits mode without applying the changes.

apply—Applies the current changes and bumps the revision number.

exit—Applies the changes, bumps the revision number, and exits VLAN configuration mode.

no—Negates a command or sets its defaults; valid values are vlan and vtp.

reset—Abandons the current changes and rereads the current database.

show—Displays the database information.

vlan—Accesses the subcommands to add, delete, or modify values that are associated with a single VLAN. For information about the vlan subcommands, see the vlan (VLAN Database mode) command.

vtp—Accesses the subcommands to perform VTP administrative functions. For information about the vtp subcommands, see the vtp client command.

Examples

This example shows how to enter VLAN configuration mode:

Switch# vlan database
Switch(vlan)# 

This example shows how to exit VLAN configuration mode without applying changes after you are in VLAN configuration mode:

Switch(vlan)# abort
Aborting....
Switch#   

This example shows how to delete a VLAN after you are in VLAN configuration mode:

Switch(vlan)# no vlan 100
Deleting VLAN 100...
Switch(vlan)# 

This example shows how to turn off pruning after you are in VLAN configuration mode:

Switch(vlan)# no vtp pruning
Pruning switched OFF
Switch(vlan)#           

Related Commands

show vlan

vlan dot1q tag native

To enable tagging of the native VLAN frames on all 802.1Q trunk ports, use the vlan dot1q tag native command. To disable tagging of native VLAN frames, use the no form of this command.

vlan dot1q tag native

no vlan dot1q tag native

Syntax Description

This command has no arguments or keywords.

Defaults

802.1Q native VLAN tagging is disabled.

Command Modes

Global configuration

Command History

Release
Modification

12.2(18)EW

This command was first introduced on the Catalyst 4500 series switch.


Usage Guidelines

When enabled, the native VLAN packets exiting all 802.1Q trunk ports are tagged unless the port is explicitly configured to disable native VLAN tagging.

When disabled, the native VLAN packets exiting all 802.1Q trunk ports are not tagged.

You can use this command with 802.1Q tunneling. This feature operates on an edge switch of a service-provider network and expands VLAN space by using a VLAN-in-VLAN hierarchy and by tagging the tagged packets. You must use the 802.1Q trunk ports for sending out the packets to the service-provider network. However, the packets going through the core of the service-provider network might also be carried on the 802.1Q trunks. If the native VLANs of an 802.1Q trunk match the native VLAN of a tunneling port on the same switch, the traffic on the native VLAN is not tagged on the sending trunk port. This command ensures that the native VLAN packets on all 802.1Q trunk ports are tagged.

Examples

This example shows how to enable 802.1Q tagging on the native VLAN frames and verify the configuration:

Switch# config terminal
Switch (config)# vlan dot1q tag native
Switch (config)# end
Switch# show vlan dot1q tag native
dot1q native vlan tagging is enabled

Related Commands

switchport private-vlan trunk native vlan tag
switchport trunk

vlan filter

To apply a VLAN access map, use the vlan filter command. To clear the VLAN access maps from VLANs or interfaces, use the no form of this command.

vlan filter map-name {vlan-list vlan-list}

no vlan filter map-name {vlan-list [vlan-list]}

Syntax Description

map-name

VLAN access-map tag.

vlan-list vlan-list

Specifies the VLAN list; see the "Usage Guidelines" section for valid values.


Defaults

This command has no default settings.

Command Modes

Global configuration

Command History

Release
Modification

12.1(12c)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

When configuring an action clause in a VLAN access map, note the following:

You can apply the VLAN access map to one or more VLANs.

The vlan-list parameter can be a single VLAN ID, a list of VLAN IDs, or VLAN ID ranges (vlan-id-vlan-id). Multiple entries are separated by (-), (hyphen), or (,) (comma).

You can apply only one VLAN access map to each VLAN.

When entering the no form of this command, the vlan-list parameter is optional (but the keyword vlan-list is required). If you do not enter the vlan-list parameter, the VACL is removed from all the VLANs where the map-name is applied.

Examples

This example shows how to apply a VLAN access map on VLANs 7 through 9:

Switch(config)# vlan filter ganymede vlan-list 7-9 
Switch(config)# 

vlan internal allocation policy

Use the vlan internal allocation policy command to configure the internal VLAN allocation scheme. To return to the default setting, use the no form of this command.

vlan internal allocation policy {ascending | descending}

no vlan internal allocation policy

Syntax Description

ascending

Specifies to allocate internal VLANs from 1006 to 4094.

descending

Specifies to allocate internal VLANs from 4094 to 1006.


Defaults

The default is the ascending allocation scheme.

Command Modes

Global configuration mode

Command History

Release
Modification

12.1(19)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

You can configure internal VLAN allocation to be from 1006 and up or from 4094 and down.

The internal VLANs and user-configured VLANs share the 1006 to 4094 VLAN spaces. A "first come, first served" policy is used in allocating these spaces.

The vlan internal allocation policy command allows you to configure the allocation direction of the internal VLAN.

During system bootup, the internal VLANs that are required for features in the startup-config file are allocated first. The user-configured VLANs in the startup-config file are configured next. If you configure a VLAN that conflicts with an existing internal VLAN, the VLAN that you configured is put into a nonoperational status until the internal VLAN is freed and becomes available.

After you enter the write mem command and the system reloads, the reconfigured allocation scheme is used by the port manager.

Examples

This example shows how to configure the VLANs in a descending order as the internal VLAN allocation policy:

Switch(config)# vlan internal allocation policy descending 
Switch(config)# 

Related Commands

show vlan internal usage

vmps reconfirm (global configuration)

To change the reconfirmation interval for the VLAN Query Protocol (VQP) client, use the vmps reconfirm command. To return to the default setting, use the no form of this command.

vmps reconfirm interval

no vmps reconfirm

Syntax Description

interval

Queries to the VLAN Membership Policy Server (VMPS) to reconfirm dynamic VLAN assignments; valid values are from 1 to 120 minutes.


Defaults

The reconfirmation interval is 60 minutes.

Command Modes

Global configuration

Command History

Release
Modification

12.1(13)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Examples

This example shows how to set the VQP client to reconfirm dynamic VLAN entries every 20 minutes:

Switch(config)# vmps reconfirm 20
Switch(config)# 

You can verify your setting by entering the show vmps command and examining information in the Reconfirm Interval row.

Related Commands

show vmps
vmps reconfirm (privileged EXEC)

vmps reconfirm (privileged EXEC)

To immediately send VLAN Query Protocol (VQP) queries to reconfirm allthe dynamic VLAN assignments with the VLAN Membership Policy Server (VMPS), use the vmps reconfirm command.

vmps reconfirm

Syntax Description

This command has no arguments or keywords.

Defaults

This command has no default settings.

Command Modes

Privileged EXEC

Command History

Release
Modification

12.1(13)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

You can verify your setting by entering the show vmps command and examining the VMPS Action row of the Reconfirmation Status section. The show vmps command shows the result of the last time that the assignments were reconfirmed either because the reconfirmation timer expired or because the vmps reconfirm command was entered.

Examples

This example shows how to immediately send VQP queries to the VMPS:

Switch# vmps reconfirm
Switch# 

Related Commands

show vmps
vmps reconfirm (global configuration)

vmps retry

To configure the per-server retry count for the VLAN Query Protocol (VQP) client, use the vmps retry command. To return to the default setting, use the no form of this command.

vmps retry count

no vmps retry

Syntax Description

count

Number of attempts to contact the VLAN Membership Policy Server (VMPS) by the client before querying the next server in the list; valid values are from 1 to 10.


Defaults

The retry count is 3.

Command Modes

Global configuration

Command History

Release
Modification

12.1(13)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

You can verify your setting by entering the show vmps command and examining information in the Server Retry Count row.

Examples

This example shows how to set the retry count to 7:

Switch(config)# vmps retry 7

Related Commands

show vmps

vmps server

To configure the primary VLAN Membership Policy Server (VMPS) and up to three secondary servers, use the vmps server command. To remove a VMPS server, use the no form of this command.

vmps server ipaddress [primary]

no vmps server ipaddress

Syntax Description

ipaddress

IP address or host name of the primary or secondary VMPS servers. If you specify a hostname, the Domain Name System (DNS) server must be configured.

primary

(Optional) Determines whether primary or secondary VMPS servers are being configured.


Defaults

No primary or secondary VMPS servers are defined.

Command Modes

Global configuration

Command History

Release
Modification

12.1(4)EA1

This command was first introduced.


Usage Guidelines

The first server that you entered is automatically selected as the primary server whether or not primary is entered. You can override the first server address by using primary in a subsequent command.

If a member switch in a cluster configuration does not have an IP address, the cluster does not use the VMPS server that is configured for that member switch. Instead, the cluster uses the VMPS server on the command switch, and the command switch proxies the VMPS requests. The VMPS server treats the cluster as a single switch and uses the IP address of the command switch to respond to requests.

When using the no form without specifying the ipaddress, all configured servers are deleted. If you delete all servers when dynamic-access ports are present, the switch cannot forward the packets from the new sources on these ports because it cannot query the VMPS.

You can verify your setting by entering the show vmps command and examining information in the VMPS Domain Server row.

Examples

This example shows how to configure the server with IP address 191.10.49.20 as the primary VMPS server. The servers with IP addresses 191.10.49.21 and 191.10.49.22 are configured as secondary servers:

Switch(config)# vmps server 191.10.49.20 primary
Switch(config)# vmps server 191.10.49.21
Switch(config)# vmps server 191.10.49.22
Switch(config)# 

This example shows how to delete the server with IP address 191.10.49.21:

Switch(config)# no vmps server 191.10.49.21
Switch(config)# 

Related Commands

show vmps

vtp (global configuration mode)

To modify the name of a VTP configuration storage file, use the vtp command. To clear a filename, use the no form of this command.

vtp {{file filename} | {if-id name}}

no vtp {{file filename} | {if-id name}}

Syntax Description

file filename

Specifies the IFS file where VTP configuration will be stored.

if-id name

Specifies the name of the interface providing the VTP updater ID for this device, where the if-id name is an ASCII string limited to 255 characters.


Defaults

Disabled

Command Modes

Global configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

You cannot use the vtp file command to load a new database. You can use it only to rename the file in which the existing database is stored.

You can use the vtp if-id command to specify the name of the interface providing the VTP updater ID for this device. The VTP updater is the device that adds, deletes, or modifies VLANs to a network, and triggers a VTP updater to inform the rest of the system of the changes.

Examples

This example shows how to specify the IFS file system file where VTP configuration is stored:

Switch(config)# vtp file vtpconfig
Setting device to store VLAN database at filename vtpconfig.   
Switch(config)# 

This example shows how to specify the name of the interface providing the VTP updater ID:

Switch(config)# vtp if-id fastethernet
Switch(config)# 

Related Commands

show vtp

vtp client

To place a device in VTP client mode, use the vtp client command. To return to VTP server mode, use the no form of this command.

vtp client

no vtp client

Syntax Description

This command has no arguments or keywords.

Defaults

Disabled

Command Modes

VLAN configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

If the receiving switch is in client mode, the client switch changes its configuration to duplicate the configuration of the server. If you have switches in client mode, make sure to make all VTP or VLAN configuration changes on a switch in server mode.

The vtp server command is the functional equivalent of no vtp client except that it does not return an error if the device is not in client mode.

Examples

This example shows how to place the device in VTP client mode:

Switch(vlan-config)# vtp client
Switch(vlan-config)# 

Related Commands

show vtp
vtp (global configuration mode)

vtp domain

To configure the administrative domain name for a device, use the vtp domain command.

vtp domain domain-name

Syntax Description

domain-name

Name of the domain.


Defaults

This command has no default settings.

Command Modes

VLAN configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

When you define the domain-name, the domain name is case sensitive and can be from 1 to 32 characters.

You must set a domain name before you can transmit any VTP advertisements.

Even if you do not set a domain name, the device will leave the no-management-domain state upon receiving the first VTP summary packet on any port that is currently trunking.

If the device receives its domain from a summary packet, it resets its configuration revision number to zero. Once the device leaves the no-management-domain state, it can never be configured to reenter the number except by cleaning NVRAM and reloading.

Examples

This example shows how to set the devices administrative domain:

Switch(vlan-config)# vtp domain DomainChandon
Switch(vlan-config)# 

Related Commands

show vtp
vtp (global configuration mode)

vtp password

To create a VTP domain password, use the vtp password command. To delete the password, use the no form of this command.

vtp password password-value

no vtp password

Syntax Description

password-value

An ASCII string, from 1 to 32 characters, identifying the administrative domain for the device.


Defaults

Disabled

Command Modes

VLAN configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Examples

This example shows how to create a VTP domain password:

Switch(vlan-config)# vtp password DomainChandon
Switch(vlan-config)# 

This example shows how to delete the VTP domain password:

Switch(vlan-config)# no vtp password
Clearing device VLAN database password.
Switch(vlan-config)#                                       

Related Commands

show vtp
vtp (global configuration mode)

vtp pruning

To enable pruning in the VLAN database, use the vtp pruning command. To disable pruning in the VLAN database, use the no form of this command.

vtp pruning

no vtp pruning

Syntax Description

This command has no arguments or keywords.

Defaults

Disabled

Command Modes

VLAN configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

VTP pruning causes information about each pruning-eligible VLAN to be removed from VTP updates if there are no stations belonging to that VLAN.

Examples

This example shows how to enable pruning in the VLAN database:

Switch(vlan-config)# vtp pruning
Pruning switched ON
Switch(vlan-config)# 

This example shows how to disable pruning in the VLAN database:

Switch(vlan-config)# no vtp pruning
Pruning switched OFF
Switch(vlan-config)# 

Related Commands

show vtp
vtp (global configuration mode)

vtp server

To place the device in VTP server mode, use the vtp server command.

vtp server

Syntax Description

This command has no arguments or keywords.

Defaults

Enabled

Command Modes

VLAN configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

If you make a change to the VTP or VLAN configuration on a switch in server mode, that change is propagated to all the switches in the same VTP domain.

You can set VTP to either server or client mode only when you disable dynamic VLAN creation.

If the receiving switch is in server mode, the configuration is not changed.

The vtp server command is the functional equivalent of no vtp client, except that it does not return an error if the device is not in client mode.

Examples

This example shows how to place the device in VTP server mode:

Switch(vlan-config)# vtp server
Switch(vlan-config)# 

Related Commands

show vtp
vtp (global configuration mode)

vtp transparent

To place a device in VTP transparent mode, use the vtp transparent command. To return to VTP server mode, use the no form of this command.

vtp transparent

no vtp transparent

Syntax Description

This command has no arguments or keywords.

Defaults

Disabled

Command Modes

VLAN configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

The vtp transparent command disables VTP from the domain but does not remove the domain from the switch.

If the receiving switch is in transparent mode, the configuration is not changed. The switches in transparent mode do not participate in VTP. If you make VTP or VLAN configuration changes on a switch in transparent mode, the changes are not propagated to the other switches in the network.

The vtp server command is similar to the no vtp transparent command, except that it does not return an error if the device is not in transparent mode.

Examples

This example shows how to place the device in VTP transparent mode:

Switch(vlan-config)# vtp transparent
Switch(vlan-config)# 

This example shows how to return the device to VTP server mode:

Switch(vlan-config)# no vtp transparent
Switch(vlan-config)# 

Related Commands

show vtp
vtp (global configuration mode)

vtp v2-mode

To enable version 2 mode, use the vtp v2-mode command. To disable version 2 mode, use the no form of this command.

vtp v2-mode

no vtp v2-mode

Syntax Description

This command has no arguments or keywords.

Defaults

Disabled

Command Modes

VLAN configuration

Command History

Release
Modification

12.1(8a)EW

Support for this command was introduced on the Catalyst 4500 series switch.


Usage Guidelines

All switches in a VTP domain must run the same version of VTP. VTP version 1 and VTP version 2 do not operate on switches in the same VTP domain.

If all switches in a domain are VTP version 2-capable, you only need to enable VTP version 2 on one switch; the version number is then propagated to the other version 2-capable switches in the VTP domain.

If you toggle the version 2 mode, the parameters of certain default VLANs will be modified.

Examples

This example shows how to enable version 2 mode in the VLAN database:

Switch(vlan-config)# vtp v2-mode
Switch(vlan-config)# 

This example shows how to disable version 2 mode in the VLAN database:

Switch(vlan-config)# no vtp v2-mode
Switch(vlan-config)# 

Related Commands

show vtp
vtp (global configuration mode)