Configuring Interface Characteristics

Finding Feature Information

Your software release may not support all the features documented in this module. For the latest caveats and feature information, see Bug Search Tool and the release notes for your platform and software release. To find information about the features documented in this module, and to see a list of the releases in which each feature is supported, see the feature information table at the end of this module.

Use Cisco Feature Navigator to find information about platform support and Cisco software image support. To access Cisco Feature Navigator, go to https://cfnng.cisco.com/. An account on Cisco.com is not required.

Information About Configuring Interface Characteristics

Interface Types

This section describes the different types of interfaces supported by the switch. The rest of the chapter describes configuration procedures for physical interface characteristics.

Port-Based VLANs

A VLAN is a switched network that is logically segmented by function, team, or application, without regard to the physical location of the users. Packets received on a port are forwarded only to ports that belong to the same VLAN as the receiving port. Network devices in different VLANs cannot communicate with one another without a Layer 3 device to route traffic between the VLANs.

VLAN partitions provide hard firewalls for traffic in the VLAN, and each VLAN has its own MAC address table. A VLAN comes into existence when a local port is configured to be associated with the VLAN, when the VLAN Trunking Protocol (VTP) learns of its existence from a neighbor on a trunk, or when a user creates a VLAN.

To configure VLANs, use the vlan vlan-id global configuration command to enter VLAN configuration mode. The VLAN configurations for normal-range VLANs (VLAN IDs 1 to 1005) are saved in the VLAN database. If VTP is version 1 or 2, to configure extended-range VLANs (VLAN IDs 1006 to 4094), you must first set VTP mode to transparent. Extended-range VLANs created in transparent mode are not added to the VLAN database but are saved in the switch running configuration. With VTP version 3, you can create extended-range VLANs in client or server mode. These VLANs are saved in the VLAN database.

Add ports to a VLAN by using the switchport interface configuration commands:

  • Identify the interface.

  • For a trunk port, set trunk characteristics, and, if desired, define the VLANs to which it can belong.

  • For an access port, set and define the VLAN to which it belongs.

Switch Ports

Switch ports are Layer 2-only interfaces associated with a physical port. Switch ports belong to one or more VLANs. A switch port can be an access port or a trunk port. switch ports are used for managing the physical interface and associated Layer 2 protocols and do not handle routing or bridging.

Configure switch ports by using the switchport interface configuration commands.

Access Ports

An access port belongs to and carries the traffic of only one VLAN (unless it is configured as a voice VLAN port). Traffic is received and sent in native formats with no VLAN tagging. Traffic arriving on an access port is assumed to belong to the VLAN assigned to the port.

The types of access ports supported are:

  • Static access ports are manually assigned to a VLAN (or through a RADIUS server for use with IEEE 802.1x.

  • VLAN membership of dynamic access ports is learned through incoming packets. By default, a dynamic access port is not a member of any VLAN, and forwarding to and from the port is enabled only when the VLAN membership of the port is discovered. Dynamic access ports on the switch are assigned to a VLAN by a VLAN Membership Policy Server (VMPS). The VMPS can be a Catalyst 6500 series switch; the switch cannot be a VMPS server.

You can also configure an access port with an attached Cisco IP Phone to use one VLAN for voice traffic and another VLAN for data traffic from a device attached to the phone.

Trunk Ports

A trunk port carries the traffic of multiple VLANs and by default is a member of all VLANs in the VLAN database.

Although by default, a trunk port is a member of every VLAN known to the VTP, you can limit VLAN membership by configuring an allowed list of VLANs for each trunk port. The list of allowed VLANs does not affect any other port but the associated trunk port. By default, all possible VLANs (VLAN ID 1 to 4094) are in the allowed list. A trunk port can become a member of a VLAN only if VTP knows of the VLAN and if the VLAN is in the enabled state. If VTP learns of a new, enabled VLAN and the VLAN is in the allowed list for a trunk port, the trunk port automatically becomes a member of that VLAN and traffic is forwarded to and from the trunk port for that VLAN. If VTP learns of a new, enabled VLAN that is not in the allowed list for a trunk port, the port does not become a member of the VLAN, and no traffic for the VLAN is forwarded to or from the port.

Switch Virtual Interfaces

A switch virtual interface (SVI) represents a VLAN of switch ports as one interface to the routing or bridging function in the system. You can associate only one SVI with a VLAN. You configure an SVI for a VLAN only to route between VLANs or to provide IP host connectivity to the switch. By default, an SVI is created for the default VLAN (VLAN 1) to permit remote switch administration. Additional SVIs must be explicitly configured.


Note

You cannot delete interface VLAN 1.

SVIs provide IP host connectivity only to the system. SVIs are created the first time that you enter the vlan interface configuration command for a VLAN interface. The VLAN corresponds to the VLAN tag associated with data frames on an IEEE 802.1Q encapsulated trunk or the VLAN ID configured for an access port. Configure a VLAN interface for each VLAN for which you want to route traffic, and assign it an IP address.

You can also use the interface range command to configure existing VLAN SVIs within the range. The commands entered under the interface range command are applied to all existing VLAN SVIs within the range. You can enter the command interface range create vlan x - y to create all VLANs in the specified range that do not already exist. When the VLAN interface is created, interface range vlan id can be used to configure the VLAN interface.

When you create an SVI, it does not become active until it is associated with a physical port.

EtherChannel Port Groups

EtherChannel port groups treat multiple switch ports as one switch port. These port groups act as a single logical port for high-bandwidth connections between switches or between switches and servers. An EtherChannel balances the traffic load across the links in the channel. If a link within the EtherChannel fails, traffic previously carried over the failed link changes to the remaining links. You can group multiple trunk ports into one logical trunk port or multiple access ports into one logical access port. Most protocols operate over either single ports or aggregated switch ports and do not recognize the physical ports within the port group. Exceptions are the DTP, the Cisco Discovery Protocol (CDP), and the Port Aggregation Protocol (PAgP), which operate only on physical ports.

When you configure an EtherChannel, you create a port-channel logical interface and assign an interface to the EtherChannel. For Layer 2 interfaces, use the channel-group interface configuration command to dynamically create the port-channel logical interface. This command binds the physical and logical ports together.

Power over Ethernet Ports

A PoE-capable switch port automatically supplies power to one of these connected devices if the switch senses that there is no power on the circuit:

  • a Cisco pre-standard powered device (such as a Cisco IP Phone or a Cisco Aironet Access Point)

  • an IEEE 802.3af-compliant powered device

  • an IEEE 802.3at-compliant powered device

A powered device can receive redundant power when it is connected to a PoE switch port and to an AC power source. The device does not receive redundant power when it is only connected to the PoE port.

After the switch detects a powered device, the switch determines the device power requirements and then grants or denies power to the device. The switch can also sense the real-time power consumption of the device by monitoring and policing the power usage.

Interface Connections

Devices within a single VLAN can communicate directly through any switch. Ports in different VLANs cannot exchange data without going through a routing device.

In the following configuration example, when Host A in VLAN 20 sends data to Host B in VLAN 30, the data must go from Host A to the device, to the router, back to the device, and then to Host B.

Figure 1. Connecting VLANs with the Switch

With a standard Layer 2 switch, ports in different VLANs have to exchange information through a router.


Note

The Catalyst 3560-CX and 2960-CX switches do not support stacking. Ignore all references to stacking throughout this book.

Interface Configuration Mode

The switch supports these interface types:

  • VLANs—switch virtual interfaces

  • Port channels—EtherChannel interfaces

  • Type—Port types depend on those supported on theswitch. Possible types are: Fast Ethernet (fastethernet or fa) for 10/100 Mb/s Ethernet, Gigabit Ethernet (gigabitethernet or gi) for 10/100/1000 Mb/s Ethernet ports, 10-Gigabit Ethernet (tengigabitethernet or te) for 10,000 Mb/s, or small form-factor pluggable (SFP) module Gigabit Ethernet interfaces.

  • Module number—The module or slot number on the switch (always 0).

You can also configure a range of interfaces. You can identify physical interfaces by looking at the switch. You can also use the show privileged EXEC commands to display information about a specific interface or all the interfaces. The remainder of this chapter primarily provides physical interface configuration procedures.


Note

Configuration examples and outputs in this book might not be specific to your switch, particularly regarding the presence of a stack member number.

Default Ethernet Interface Configuration

This table shows the Ethernet interface default configuration, including some features that apply only to Layer 2 interfaces.

Table 1. Default Layer 2 Ethernet Interface Configuration

Feature

Default Setting

Allowed VLAN range

VLANs 1– 4094.

Default VLAN (for access ports)

VLAN 1.

Native VLAN (for IEEE 802.1Q trunks)

VLAN 1.

802.1p priority-tagged traffic

Drop all packets tagged with VLAN 0.

VLAN trunking

Switchport mode dynamic auto (supports DTP).

Port enable state

All ports are enabled.

Port description

None defined.

Speed

Autonegotiate. (Not supported on the 10-Gigabit interfaces.)

Duplex mode

Autonegotiate. (Not supported on the 10-Gigabit interfaces.)

Flow control

Flow control is set to receive: off . It is always off for sent packets.

EtherChannel (PAgP)

Disabled on all Ethernet ports.

Port blocking (unknown multicast and unknown unicast traffic)

Disabled (not blocked).

Broadcast, multicast, and unicast storm control

Disabled.

Protected port

Disabled.

Port security

Disabled.

Port Fast

Disabled.

Auto-MDIX

Enabled.

Note 

The switch might not support a pre-standard powered device—such as Cisco IP phones and access points that do not fully support IEEE 802.3af—if that powered device is connected to the switch through a crossover cable. This is regardless of whether auto-MIDX is enabled on the switch port.

Power over Ethernet (PoE)

Enabled (auto).

Keepalive messages

Disabled on SFP module ports; enabled on all other ports.

Interface Speed and Duplex Mode

Ethernet interfaces on the switch operate at 10, 100, 1000, or 10,000 Mb/s and in either full- or half-duplex mode. In full-duplex mode, two stations can send and receive traffic at the same time. Normally, 10-Mb/s ports operate in half-duplex mode, which means that stations can either receive or send traffic.

Switch modules include Fast Ethernet (10/100-Mb/s) ports, Gigabit Ethernet (10/100/1000-Mb/s) ports, 10-Gigabit Ethernet ports, and small form-factor pluggable (SFP) module slots supporting SFP modules.

Speed and Duplex Configuration Guidelines

When configuring an interface speed and duplex mode, note these guidelines:

  • The 10-Gigabit Ethernet ports do not support the speed and duplex features. These ports operate only at 10,000 Mb/s and in full-duplex mode.

  • Fast Ethernet (10/100-Mb/s) ports support all speed and duplex options.

  • Gigabit Ethernet (10/100/1000-Mb/s) ports support all speed options and all duplex options (auto, half, and full). However, Gigabit Ethernet ports operating at 1000 Mb/s do not support half-duplex mode.

  • For SFP module ports, the speed and duplex CLI options change depending on the SFP module type:

    • The 1000BASE-x (where -x is -BX, -CWDM, -LX, -SX, and -ZX) SFP module ports support the nonegotiate keyword in the speed interface configuration command. Duplex options are not supported.

    • The 1000BASE-T SFP module ports support the same speed and duplex options as the 10/100/1000-Mb/s ports.

  • If both ends of the line support autonegotiation, we highly recommend the default setting of auto negotiation.

  • If one interface supports autonegotiation and the other end does not, configure duplex and speed on both interfaces; do not use the auto setting on the supported side.

  • When STP is enabled and a port is reconfigured, the switch can take up to 30 seconds to check for loops. The port LED is amber while STP reconfigures.

  • As best practice, we suggest configuring the speed and duplex options on a link to auto or to fixed on both the ends. If one side of the link is configured to auto and the other side is configured to fixed, the link will not be up and this is expected.

    The speed on the switch is autonegotiable and it can detect a peer device only if the peer device supports autonegotiation. If the peer device does not support autonegotiation, and autonegotiation is enabled on the switch, the switch goes into half duplex mode.


Caution

Changing the interface speed and duplex mode configuration might shut down and re-enable the interface during the reconfiguration.

IEEE 802.3x Flow Control

Flow control enables connected Ethernet ports to control traffic rates during congestion by allowing congested nodes to pause link operation at the other end. If one port experiences congestion and cannot receive any more traffic, it notifies the other port by sending a pause frame to stop sending until the condition clears. Upon receipt of a pause frame, the sending device stops sending any data packets, which prevents any loss of data packets during the congestion period.


Note

The switch ports can receive, but not send, pause frames.

Use the flowcontrol interface configuration command to set the interface’s ability to receive pause frames to on , off , or desired .

When set to desired , an interface can operate with an attached device that is required to send flow-control packets or with an attached device that is not required to but can send flow-control packets.

These rules apply to flow control settings on the device:

  • receive on (or desired ): The port cannot send pause frames but can operate with an attached device that is required to or can send pause frames; the port can receive pause frames.

  • receive off : Flow control does not operate in either direction. In case of congestion, no indication is given to the link partner, and no pause frames are sent or received by either device.


Note

For details on the command settings and the resulting flow control resolution on local and remote ports, see the flowcontrol interface configuration command in the command reference for this release.

How to Configure Interface Characteristics

Configuring Interfaces

These general instructions apply to all interface configuration processes.

Procedure

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

interface

Example:


Switch(config)# interface gigabitethernet 1/0/1
Switch(config-if)#

Identifies the interface type, the switch number (only on stacking-capable switches), and the number of the connector.

Note 

You do not need to add a space between the interface type and the interface number. For example, in the preceding line, you can specify either gigabitethernet 1/0/1 , gigabitethernet1/0/1 , gi 1/0/1 , or gi1/0/1 .

Step 4

Follow each interface command with the interface configuration commands that the interface requires.

Defines the protocols and applications that will run on the interface. The commands are collected and applied to the interface when you enter another interface command or enter end to return to privileged EXEC mode.

Step 5

interface range or interface range macro

(Optional) Configures a range of interfaces.

Note 

Interfaces configured in a range must be the same type and must be configured with the same feature options.

Step 6

show interfaces

Displays a list of all interfaces on or configured for the switch. A report is provided for each interface that the device supports or for the specified interface.

Adding a Description for an Interface

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface interface-id
  4. description string
  5. end
  6. show interfaces interface-id description
  7. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

interface interface-id

Example:


Switch(config)# interface gigabitethernet 1/0/2

Specifies the interface for which you are adding a description, and enter interface configuration mode.

Step 4

description string

Example:


Switch(config-if)# description Connects to Marketing

Adds a description (up to 240 characters) for an interface.

Step 5

end

Example:


Switch(config-if)# end

Returns to privileged EXEC mode.

Step 6

show interfaces interface-id description

Verifies your entry.

Step 7

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring a Range of Interfaces

To configure multiple interfaces with the same configuration parameters, use the interface range global configuration command. When you enter the interface-range configuration mode, all command parameters that you enter are attributed to all interfaces within that range until you exit this mode.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface range {port-range | macro macro_name}
  4. end
  5. show interfaces [interface-id]
  6. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

interface range {port-range | macro macro_name}

Example:


Switch(config)# interface range macro

Specifies the range of interfaces (VLANs or physical ports) to be configured, and enter interface-range configuration mode.

  • You can use the interface range command to configure up to five port ranges or a previously defined macro.

  • The macro variable is explained in the section on Configuring and Using Interface Range Macros.

  • In a comma-separated port-range , you must enter the interface type for each entry and enter spaces before and after the comma.

  • In a hyphen-separated port-range , you do not need to re-enter the interface type, but you must enter a space before the hyphen.

Note 

Use the normal configuration commands to apply the configuration parameters to all interfaces in the range. Each command is executed as it is entered.

Step 4

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 5

show interfaces [interface-id]

Example:


Switch# show interfaces

Verifies the configuration of the interfaces in the range.

Step 6

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring and Using Interface Range Macros

You can create an interface range macro to automatically select a range of interfaces for configuration. Before you can use the macro keyword in the interface range macro global configuration command string, you must use the define interface-range global configuration command to define the macro.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. define interface-range macro_name interface-range
  4. interface range macro macro_name
  5. end
  6. show running-config | include define
  7. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

define interface-range macro_name interface-range

Example:


Switch(config)# define interface-range enet_list gigabitethernet 1/0/1 - 2

Defines the interface-range macro, and save it in NVRAM.

  • The macro_name is a 32-character maximum character string.

  • A macro can contain up to five comma-separated interface ranges.

  • Each interface-range must consist of the same port type.

Note 

Before you can use the macro keyword in the interface range macro global configuration command string, you must use the define interface-range global configuration command to define the macro.

Step 4

interface range macro macro_name

Example:


Switch(config)# interface range macro enet_list

Selects the interface range to be configured using the values saved in the interface-range macro called macro_name .

You can now use the normal configuration commands to apply the configuration to all interfaces in the defined macro.

Step 5

end

Example:


Switch(config)# end

Returns to privileged EXEC mode.

Step 6

show running-config | include define

Example:


Switch# show running-config | include define

Shows the defined interface range macro configuration.

Step 7

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring Ethernet Interfaces

Setting the Interface Speed and Duplex Parameters

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface interface-id
  4. speed {10 | 100 | 1000 | 2500 | 5000 | 10000 | auto [10 | 100 | 1000 | 2500 | 5000 | 10000] | nonegotiate}
  5. duplex {auto | full | half}
  6. end
  7. show interfaces interface-id
  8. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:

Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:

Switch# configure terminal

Enters global configuration mode.

Step 3

interface interface-id

Example:

Switch(config)# interface gigabitethernet 1/0/3

Specifies the physical interface to be configured, and enter interface configuration mode.

Step 4

speed {10 | 100 | 1000 | 2500 | 5000 | 10000 | auto [10 | 100 | 1000 | 2500 | 5000 | 10000] | nonegotiate}

Example:

Switch(config-if)# speed 10

Enter the appropriate speed parameter for the interface:

  • Enter 10 , 100 , 1000 2500 , 5000 , or 10000 to set a specific speed for the interface.

  • Enter auto to enable the interface to autonegotiate speed with the connected device. If you specify a speed and also set the auto keyword, the port autonegotiates only at the specified speeds.

  • The nonegotiate keyword is available only for SFP module ports. SFP module ports operate only at 1000 Mb/s but can be configured to not negotiate if connected to a device that does not support autonegotiation.

Step 5

duplex {auto | full | half}

Example:

Switch(config-if)# duplex half

This command is not available on a 10-Gigabit Ethernet interface.

Enter the duplex parameter for the interface.

Enable half-duplex mode (for interfaces operating only at 10 or 100 Mb/s). You cannot configure half-duplex mode for interfaces operating at 1000 Mb/s.

You can configure the duplex setting when the speed is set to auto .

Step 6

end

Example:

Switch(config-if)# end

Returns to privileged EXEC mode.

Step 7

show interfaces interface-id

Example:

Switch# show interfaces gigabitethernet 1/0/3

Displays the interface speed and duplex mode configuration.

Step 8

copy running-config startup-config

Example:

Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Configuring IEEE 802.3x Flow Control

SUMMARY STEPS

  1. configure terminal
  2. interface interface-id
  3. flowcontrol {receive} {on | off | desired}
  4. end
  5. show interfaces interface-id
  6. copy running-config startup-config

DETAILED STEPS

  Command or Action Purpose
Step 1

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode

Step 2

interface interface-id

Example:


Switch(config)# interface gigabitethernet 1/0/1

Specifies the physical interface to be configured, and enter interface configuration mode.

Step 3

flowcontrol {receive} {on | off | desired}

Example:


Switch(config-if)# flowcontrol receive on

Configures the flow control mode for the port.

Step 4

end

Example:


Switch(config-if)# end

Returns to privileged EXEC mode.

Step 5

show interfaces interface-id

Example:


Switch# show interfaces gigabitethernet 1/0/1

Verifies the interface flow control settings.

Step 6

copy running-config startup-config

Example:


Switch# copy running-config startup-config

(Optional) Saves your entries in the configuration file.

Monitoring Interface Characteristics

Monitoring Interface Status

Commands entered at the privileged EXEC prompt display information about the interface, including the versions of the software and the hardware, the configuration, and statistics about the interfaces.

Table 2. Show Commands for Interfaces

Command

Purpose

show interfaces interface-number downshift modulemodule-number

Displays the downshift status details of the specified interfaces and modules.

show interfaces interface-id status [err-disabled]

Displays interface status or a list of interfaces in the error-disabled state.

show interfaces [interface-id] switchport

Displays administrative and operational status of switching (nonrouting) ports. You can use this command to find out if a port is in routing or in switching mode.

show interfaces [interface-id] description

Displays the description configured on an interface or all interfaces and the interface status.

show ip interface [interface-id]

Displays the usability status of all interfaces configured for IP routing or the specified interface.

show interface [interface-id] stats

Displays the input and output packets by the switching path for the interface.

show interfaces interface-id

(Optional) Displays speed and duplex on the interface.

show interfaces transceiver dom-supported-list

(Optional) Displays Digital Optical Monitoring (DOM) status on the connect SFP modules.

show interfaces transceiver properties

(Optional) Displays temperature, voltage, or amount of current on the interface.

show interfaces [interface-id] [{transceiver properties | detail}] module number]

Displays physical and operational status about an SFP module.

show running-config interface [interface-id]

Displays the running configuration in RAM for the interface.

show version

Displays the hardware configuration, software version, the names and sources of configuration files, and the boot images.

show controllers ethernet-controller interface-id phy

Displays the operational state of the auto-MDIX feature on the interface.

Shutting Down and Restarting the Interface

Shutting down an interface disables all functions on the specified interface and marks the interface as unavailable on all monitoring command displays. This information is communicated to other network servers through all dynamic routing protocols. The interface is not mentioned in any routing updates.

SUMMARY STEPS

  1. enable
  2. configure terminal
  3. interface {vlan vlan-id} | {{{fastethernet | gigabitethernetinterface-id} | {port-channel port-channel-number}
  4. shutdown
  5. no shutdown
  6. end
  7. show running-config

DETAILED STEPS

  Command or Action Purpose
Step 1

enable

Example:


Switch> enable

Enables privileged EXEC mode.

  • Enter your password if prompted.

Step 2

configure terminal

Example:


Switch# configure terminal

Enters global configuration mode.

Step 3

interface {vlan vlan-id} | {{{fastethernet | gigabitethernetinterface-id} | {port-channel port-channel-number}

Example:


Switch(config)# interface gigabitethernet 1/0/2

Selects the interface to be configured.

Step 4

shutdown

Example:


Switch(config-if)# shutdown

Shuts down an interface.

Step 5

no shutdown

Example:


Switch(config-if)# no shutdown

Restarts an interface.

Step 6

end

Example:


Switch(config-if)# end

Returns to privileged EXEC mode.

Step 7

show running-config

Example:


Switch# show running-config

Verifies your entries.

Clearing and Resetting Interfaces and Counters

Table 3. Clear Commands for Interfaces

Command

Purpose

clear counters [interface-id]

Clears interface counters.

clear interface interface-id

Resets the hardware logic on an interface.

clear line [number | console 0 | vty number]

Resets the hardware logic on an asynchronous serial line.

Note

The clear counters privileged EXEC command does not clear counters retrieved by using Simple Network Management Protocol (SNMP), but only those seen with the show interface privileged EXEC command.

Configuration Examples for Interface Characteristics

Adding a Description to an Interface: Example

Identifying Interfaces on a Stack-Capable Switch: Examples

To configure 10/100/1000 port 4 on a standalone switch, enter this command:


Switch(config)# interface gigabitethernet1/1/4

Configuring a Range of Interfaces: Examples

This example shows how to use the interface range global configuration command to set the speed to 100 Mb/s on ports 1 to 4 on switch 1: 


Switch# configure terminal
Switch(config)# interface range gigabitethernet 1/0/1 - 4 
Switch(config-if-range)# speed 100

This example shows how to use a comma to add different interface type strings to the range to enable Gigabit Ethernet ports 1 to 3 and 10-Gigabit Ethernet ports 1 and 2 to receive flow-control pause frames: 


Switch# configure terminal
Switch(config)# interface range gigabitethernet1/0/1 - 3 , tengigabitethernet1/1/1 - 2
Switch(config-if-range)# flowcontrol receive on

If you enter multiple configuration commands while you are in interface-range mode, each command is executed as it is entered. The commands are not batched and executed after you exit interface-range mode. If you exit interface-range configuration mode while the commands are being executed, some commands might not be executed on all interfaces in the range. Wait until the command prompt reappears before exiting interface-range configuration mode.

Configuring and Using Interface Range Macros: Examples

This example shows how to define an interface-range named enet_list to include ports 1 and 2 on switch 1 and to verify the macro configuration: 


Switch# configure terminal
Switch(config)# define interface-range enet_list gigabitethernet 1/1/1 - 2
Switch(config)# end
Switch# show running-config | include define 
define interface-range enet_list gigabitethernet 1/1/1 - 2

This example shows how to create a multiple-interface macro named macro1: 


Switch# configure terminal
Switch(config)# define interface-range macro1 gigabitethernet1/1/1 - 2, gigabitethernet1/1/5 - 7, tengigabitethernet1/1/1 -2
Switch(config)# end

This example shows how to enter interface-range configuration mode for the interface-range macro enet_list: 


Switch# configure terminal
Switch(config)# interface range macro enet_list
Switch(config-if-range)#

This example shows how to delete the interface-range macro enet_list and to verify that it was deleted. 


Switch# configure terminal
Switch(config)# no define interface-range enet_list 
Switch(config)# end
Switch# show run | include define
Switch#

Setting Interface Speed and Duplex Mode: Example

This example shows how to set the interface speed to 100 Mb/s and the duplex mode to half on a 10/100/1000 Mb/s port:


Switch# configure terminal
Switch(config)# interface gigabitethernet 1/0/3
Switch(config-if)# speed 10
Switch(config-if)# duplex half

This example shows how to set the interface speed to 100 Mb/s on a 10/100/1000 Mb/s port:


Switch# configure terminal
Switch(config)# interface gigabitethernet 1/0/2
Switch(config-if)# speed 100

Additional References

MIBs

MIB MIBs Link

All the supported MIBs for this release.

To locate and download MIBs for selected platforms, Cisco IOS releases, and feature sets, use Cisco MIB Locator found at the following URL:

http://www.cisco.com/go/mibs

Technical Assistance

Description Link

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