Interface Commands

This chapter describes the commands that can be used on different types of interfaces. These commands correspond to the interface configuration tasks included in the Cisco IOS configuration guides. Refer to the configuration guide indicated here for configuration guidelines:

For hardware technical descriptions, and for information about installing the router or access server interfaces, refer to the hardware installation and maintenance publication for your particular product.

access-list (standard)

Use the access-list global configuration command to establish MAC address access lists. Use the no form of this command to remove a single access list entry.

Syntax Description

Default

No MAC address access lists are established.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Related Commands

You can use the master indexes or search online to find documentation of related commands.

access-list (type-code)

access-list (type-code)

Use the access-list global configuration command to build type-code access lists. Use the no form of this command to remove a single access list entry.

Syntax Description

Default

No type-code access lists are built.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Type-code access lists can have an impact on system performance; therefore, keep the lists as short as possible and use wildcard bit masks whenever possible.

Access lists are evaluated according to the following algorithm:

• If the packet is Ethernet Type II or SNAP, the type-code field is used.

• Other packet type, then the LSAP is used.

If the length/type field is greater than 1500, the packet is treated as an LSAP packet unless the DSAP and SSAP fields are AAAA. If the latter is true, the packet is treated using type-code filtering.

If you have both Ethernet Type II and LSAP packets on your network, you should set up access lists for both.

Use the last item of an access list to specify a default action; for example, permit everything else or deny everything else. If nothing else in the access list matches, the default action is normally to deny access; that is, filter out all other type codes.

Related Commands

You can use the master indexes or search online to find documentation of related commands.

access-list (extended)
access-list (standard)

auto-polarity

To enable automatic receiver polarity reversal on a hub port connected to an Ethernet interface of a Cisco 2505 or Cisco 2507, use the auto-polarity hub configuration command. To disable this feature, use the no form of this command.

Syntax Description

This command has no arguments or keywords.

Default

Enabled

Command Mode

Hub configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

This command applies to a port on an Ethernet hub only.

Example

The following example enables automatic receiver polarity reversal on hub 0, ports 1 through 3:

hub ethernet 0 1 3
 auto-polarity

Related Commands

You can use the master indexes or search online to find documentation of related commands.

hub

bandwidth

To set a bandwidth value for an interface, use the bandwidth interface configuration command. Use the no form of this command to restore the default values.

Syntax Description

Default

Default bandwidth values are set during startup and can be displayed with the EXEC command show interfaces.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

The bandwidth command sets an informational parameter only; you cannot adjust the actual bandwidth of an interface with this command. For some media, such as Ethernet, the bandwidth is fixed; for other media, such as serial lines, you can change the actual bandwidth by adjusting hardware. For both classes of media, you can use the bandwidth configuration command to communicate the current bandwidth to the higher-level protocols.

Example

The following example sets the full bandwidth for DS3 transmissions:

interface serial 0
 bandwidth 44736

Related Commands

You can use the master indexes or search online to find documentation of related commands.

vines metric

cablelength

To specify the distance of the cable from the Channelized T3 Interface Processor (CT3IP) in Cisco 7500 series routers to the network equipment, use the cablelength controller configuration command. Use the no form of this command to restore the default cable length.

Syntax Description

Default

224 feet

Command Mode

Controller configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.3.

If you do not specify the cablelength command, the default cable length of 224 feet is used by the CT3IP.

Example

In the following example, the cable length for the CT3IP is set to 300:

controller t3 9/0/0
 cablelength 300

cablelength long

To increase the pulse of a signal at the receiver and decrease the pulse from the transmitter using pulse equalization and line build-out for a T1 cable on an AS5200, use the cablelength long interface configuration command. To return the pulse equalization and line build-out values to their default settings, use the no form of this command.

Syntax Description

Default

Long cable length, receiver gain of 36 dB, and transmitter loss of 0 dB.

Command Mode

Interface configuration

Usage Guidelines

Use this command for configuring the controller T1 interface on the AS5200 access server.

A pulse equalizer regenerates a signal that has been attenuated and filtered by a cable loss. Pulse equalization does not produce a simple gain, but it filters the signal to compensate for complex cable loss. A gain26 receiver gain compensates for a long cable length equivalent to 26 dB of loss, while a gain36 compensates for 36 dB of loss.

The lengthening or building out of a line is used to control far-end crosstalk. Line build-out attenuates the stronger signal from the customer installation transmitter so that the transmitting and receiving signals have similar amplitudes. A signal difference of less than 7.5 dB is ideal. Line build-out does not produce simple flat loss (also known as resistive flat loss). Instead, it simulates a cable loss of 7.5 dB, 15 dB, or 22.5 dB so that the resulting signal is handled properly by the receiving equalizer at the other end.

Example

The following example increases the receiver gain by 26 decibels and decreases the transmitting pulse by 7.5 decibels for a long cable:

AS5200(config)# controller t1 0
AS5200(config-controller)# cablelength long gain26 -7.5db

cas-group

To configure channelized T1 timeslots with channel associated signaling (also known as robbed bit signaling), which enables an AS5200 modem to answer and send an analog call, use the cas-group controller configuration command. Use the no form of this command to disable channel associated signaling for one or more timeslots.

Syntax Description

Default

Disabled

Command Mode

Controller configuration

Usage Guidelines

Use this command to enable an AS5200 modem to receive and send incoming and outgoing analog calls through each T1 controller that is configured for a channelized T1 line, which has 24 possible channels.

Switched 56 digital calls are not supported under this new feature.

Example

The following example shows you how to configure all 24 channels to support robbed bit signaling on a Cisco AS5200:

AS5200(config)# controller T1 0
AS5200(config-controller)# cas-group 1 timeslots 1-24
AS5200(config-controller)#
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 1 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 2 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 3 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 4 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 5 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 6 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 7 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 8 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 9 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 10 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 11 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 12 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 13 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 14 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 15 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 16 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 17 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 18 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 19 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 20 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 21 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 22 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 23 is up
%DSX0-5-RBSLINEUP: RBS of controller 1 timeslot 24 is up

channel-group

Use the channel-group controller configuration command to define the timeslots that belong to each T1 or E1 circuit.

Syntax Description

Default

The default line speed when configuring a T1 controller is 56 kbps.

The default line speed when configuring an E1 controller is 64 kbps.

Command Mode

Controller configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Use this command in configurations where the router or access server must communicate with a T1 or E1 fractional data line. The channel-group number may be arbitrarily assigned and must be unique for the controller. The timeslot range must match the timeslots assigned to the channel group. The service provider defines the timeslots that comprise a channel group.

Example

In the following example, three channel groups are defined. Channel-group 0 consists of a single timeslot, channel-group 8 consists of seven timeslots and runs at a speed of 64 kbps per timeslot, and channel-group 12 consists of a single timeslot.

channel-group 0 timeslots 1
channel-group 8 timeslots 5,7,12-15,20 speed 64
channel-group 12 timeslots 2

Related Commands

You can use the master indexes or search online to find documentation of related commands.

framing
linecode

clear controller lex

To reboot the LAN Extender chassis and restart its operating software, use the clear controller lex privileged EXEC command.

Syntax Description

Command Mode

Privileged EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

The clear controller lex command halts operation of the LAN Extender and performs a cold restart.

Without the prom keyword, if an image exists in Flash memory, and that image has a newer software version than the PROM image, and that image has a valid checksum, then this command runs the Flash image. If any one of these three conditions is not met, this command reloads the PROM image.

With the prom keyword, this command reloads the PROM image, regardless of any Flash image.

Examples

The following example halts operation of the LAN Extender bound to LAN Extender interface 2 and causes the LAN Extender to perform a cold restart from Flash memory:

Router# clear controller lex 2
reload remote lex controller? [confirm] yes

The following example halts operation of the LAN Extender bound to LAN Extender interface 2 and causes the LAN Extender to perform a cold restart from PROM:

Router# clear controller lex 2 prom
reload remote lex controller? [confirm] yes

clear counters

To clear the interface counters, use the clear counters EXEC command.

Syntax Description

Command Mode

EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

This command was modified in Cisco IOS Release 11.3 to include the vg-anylan interface type keyword and to change the posi keyword to pos.

This command clears all the current interface counters from the interface unless the optional arguments type and number are specified to clear only a specific interface type (serial, Ethernet, Token Ring, and so on). Table 24 lists the command keywords and their descriptions.

Examples

The following example clears all interface counters:

clear counters

The following example clears the Packet OC-3 interface counters on a POSIP card in slot 1 on a Cisco 7500 series router:

clear counters pos 1/0

The following example clears interface counters on the serial interface residing on a Cisco 1000 series LAN Extender:

clear counters lex 0 serial

Related Commands

You can use the master indexes or search online to find documentation of related commands.

show interfaces

clear hub

Use the clear hub EXEC command to reset and reinitialize the hub hardware connected to an interface of a Cisco 2505 or 2507 routers.

Syntax Description

Command Mode

EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

Example

The following example clears hub 0:

clear hub ethernet 0

Related Commands

You can use the master indexes or search online to find documentation of related commands.

hub

clear hub counters

Use the clear hub counters EXEC command to set to zero the hub counters on an interface of a Cisco 2505 or 2507 routers.

Syntax Description

Command Mode

EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

Example

The following example clears the counters displayed in a show hub command for all ports on hub 0:

clear hub counters ether 0

Related Commands

You can use the master indexes or search online to find documentation of related commands.

show hub

clear interface

Use the clear interface EXEC command to reset the hardware logic on an interface.

Syntax Description

Command Mode

EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

This command was modified in Cisco IOS Release 11.3 to include the vg-anylan interface type keyword and to change the posi keyword to pos.

Under normal circumstances, you do not need to clear the hardware logic on interfaces.

This command clears all the current interface hardware logic unless the optional arguments type and number are specified to clear only a specific interface type (serial, Ethernet, Token Ring, and so on). Table 25 lists the command keywords and their descriptions.

Examples

The following example resets the interface logic on HSSI interface 1:

clear interface hssi 1

The following example resets the interface logic on Packet OC-3 interface 0 on the POSIP in slot 1:

clear interface pos 1/0

The following example resets the interface logic on T1 0 on the CT3IP in slot 9:

clear interface serial 9/0/0:0

clear interface fastethernet

Use the clear interface fastethernet privileged EXEC command to reset the controller for a specified Fast Ethernet interface.

Syntax Description

Command Mode

Privileged EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 11.2.

Examples

The following example resets the controller for the Ethernet 0 interface on a Cisco 4500:

clear interface fastethernet 0

The following example resets the controller for the Ethernet interface located in slot 1 port 0 on a Cisco 7200 or Cisco 7500:

clear interface fastethernet 1/0

The following example resets the controller for the Ethernet interface located in slot 1 port adapter 0 port 0 on a Cisco 7500:

clear interface fastethernet 1/0/0

clear rif-cache

Use the clear rif-cache EXEC command to clear entries from the Routing Information Field (RIF) cache.

Syntax Description

This command has no arguments or keywords.

Command Mode

EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Example

The following example clears the RIF cache:

clear rif-cache

Related Commands

You can use the master indexes or search online to find documentation of related commands.

multiring

clear service-module serial

Use the clear service-module serial privileged EXEC configuration command to reset an integrated CSU/DSU.

Syntax Description

Command Mode

Privileged EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 11.2.

Use this command only in severe circumstances (for example, when the router is not responding to a CSU/DSU configuration command).

This command terminates all DTE and line loopbacks that are locally or remotely configured. It also interrupts data transmission through the router for up to 15 seconds. The software performs an automatic software reset in case of two consecutive configuration failures.

The CSU/DSU module is not reset with the clear interface command.

Caution If you experience technical difficulties with your router and intend to contact customer support, refrain from using this command. This command erases the router's past CSU/DSU performance statistics. To clear only the CSU/DSU performance statistics, issue the clear counters command.

Example

The following example resets the CSU/DSU on a router:

router# clear service-module serial 0
router#

Related Commands

You can use the master indexes or search online to find documentation of related commands.

clear counters
test service-module

clock rate

Use the clock rate interface configuration command to configure the clock rate for the hardware connections on serial interfaces such as network interface modules (NIMs) and interface processors to an acceptable bit rate. Use the no form of this command to remove the clock rate if you change the interface from a DCE to a DTE device. Using the no form of this command on a DCE interface sets the clock rate to the hardware-dependent default value.

Syntax Description

Default

No clock rate is configured.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

This command was modified in Cisco IOS Release 11.3 to include nonstandard clock rates for the PA-8T-V35, PA-8T-X21, PA-8T-232, and PA-4T+ synchronous serial port adapters.

Cable Length

Be aware that the fastest speeds might not work if your cable is too long, and that speeds faster than 148,000 bits per second are too fast for EIA/TIA-232 signaling. It is recommended that you only use the synchronous serial EIA/TIA-232 signal at speeds up to 64,000 bits per second. To permit a faster speed, use EIA/TIA-449 or V.35.

Synchronous Serial Port Adapters

For the synchronous serial port adapters (PA-8T-V35, PA-8T-X21, PA-8T-232, and PA-4T+) on Cisco 7200 series routers, and on second-generation Versatile Interface Processors (VIP2s) in Cisco 7500 series routers, the clock rate you enter is rounded (if needed) to the nearest value that your hardware can support. To display the clock rate value for the port adapter, use the show running-configuration command.

If you plan to netboot your router over a synchronous serial port adapter interface and have a boot image prior to Cisco IOS Release 11.1(9)CA that does not support nonstandard (rounded) clock rates for the port adapters, you must use one of the following standard clock rates:

1200, 2400, 4800, 9600, 19200, 38400, 56000, 64000

Examples

The following example sets the clock rate on the first serial interface to 64,000 bits per second:

interface serial 0
 clock rate 64000

The following example sets the clock rate on a synchronous serial port adapter in slot 5, port 0 to 1234567. In this example, the clock rate is adjusted to 1151526 bps.

interface serial 5/0
 clock rate 1234567
%Clockrate rounded to nearest value that your hardware can support.
%Use Exec Command 'show running-config' to see the value rounded to.

The following example configures serial interface 5/0 with a clock rate that is rounded to the nearest value that is supported by the hardware:

Router# configure terminal
Enter configuration commands, one per line.  End with CNTL/Z.
Router(config)# interface serial 5/0
Router(config-if)# clock rate 1234567
%Clockrate rounded to nearest value that your hardware can support.
%Use Exec Command 'show running-config' to see the value rounded to.
Router(config-if)# exit
Router(config)#

Router# show running-config
Building configuration...
...
!
interface Serial5/0
 no ip address
 clockrate 1151526
!
...

clock source

Use the clock source controller configuration command to specify where the clock source is obtained for use by the Channelized T3 Interface Processor (CT3IP) in Cisco 7500 series routers. Use the no form of this command to restore the default clock source.

Syntax Description

Default

internal

Command Mode

Controller configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.3.

If you do not specify the clock source command, the default clock source of internal is used by the CT3IP.

Example

In the following example, the clock source for the CT3IP is set to line:

controller t3 9/0/0
 clock source line

Related Commands

You can use the master indexes or search online to find documentation of related commands.

interface ethernet 2  squelch reduced

clock source (Cisco AS5200)

Use the clock source interface configuration command to select the clock source for the time-division multiplexing (TDM) bus in a Cisco AS5200 access server. The no form of this command configures the clock source to its default setting.

Syntax Description

Defaults

Primary TDM clock source from the T1 0 controller

Secondary TDM clock source from the T1 1 controller

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.2.

To use the clocking coming in from a T1 line, configure the clock source line primary command on the T1 interface that has the most reliable clocking. Configure the clock source line secondary command on the T1 interface that has the next best known clocking. With this configuration, the primary line clocking is backed up to the secondary line if the primary clocking shuts down.

Example

The following example configures the Cisco AS5200 access server to use T1 controller 0 as the primary clock source and T1 controller 1 as the secondary clock source:

controller t1 0 
clock source line primary 
controller t1 1 
clock source line secondary 

clock source (controller)

Use the clock source controller configuration command to set the T1-line clock-source for the MIP in the Cisco 7200 series and Cisco 7500 series or for the NPM in the Cisco 4000 series.

Syntax Description

Defaults

Primary TDM clock source from the T0 controller

Secondary TDM clock source from the T1 controller

Command Mode

Controller configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

To use the clocking coming in from a T1 line, configure the clock source line primary command on the controller that has the most reliable clocking. Configure the clock source line secondary command on the controller that has the next best known clocking. With this configuration, the primary line clocking is backed up to the secondary line if the primary clocking shuts down.

Example

The following example configures the Cisco AS5200 to use the T0 controller as the primary clocking source and the

T1 controller as the secondary clocking source:

AS5200(config)# controller t1 0
AS5200(config-if)# clock source line primary
AS5200(config-if)# exit
AS5200(config)# controller t1 1
AS5200(config-if)# clock source line secondary

Related Commands

You can use the master index or search online for documentation of these and other commands.

framing
linecode

clock source (interface)

Use the clock source interface configuration command to control which clock a G.703 E1 interface will use to clock its transmitted data from. The no form of this command restores the default value.

Syntax Description

Default

By default, the applique uses the line's receive data stream.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

This command applies to a Cisco 4000 router or Cisco 7500 series router. A G.703-E1 interface

can clock its transmitted data from either its internal clock or from a clock recovered from the line's receive data stream.

Example

The following example specifies the G.703-E1 interface to clock its transmitted data from its internal clock:

clock source internal 

clock source (interface)

To control which clock a G.703-E1 interface will use to clock its transmitted data from, use the clock source interface configuration command. The no form of this command restores the default value.

Syntax Description

Default

By default, the applique uses the line's receive data stream.

Primary TDM clock source from the T0 controller on the Cisco AS5200.

Secondary TDM clock source from the T1 controller on the Cisco AS5200.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

On the Cisco 4000 router and Cisco 7500 series router, a G.703-E1 interface can clock its transmitted data from either its internal clock or from a clock recovered from the line's receive data stream.

To use the clocking coming in from a T1 line for the Cisco AS5200, configure the clock source line primary command on the controller that has the most reliable clocking. Configure the clock source line secondary command on the controller that has the next best known clocking. With this configuration, the primary line clocking is backed up to the secondary line if the primary clocking shuts down.

Example

The following example specifies the G.703-E1 interface to clock its transmitted data from its internal clock:

clock source internal

The following example configures the Cisco AS5200 to use the T0 controller as the primary clocking source and the T1 controller as the secondary clocking source:

AS5200(config)# controller t1 0
AS5200(config-if)# clock source line primary
AS5200(config-if)# exit
AS5200(config)# controller t1 1
AS5200(config-if)# clock source line secondary

cmt connect

Use the cmt connect EXEC command to start the processes that perform the connection management (CMT) function and allow the ring on one fiber to be started.

Syntax Description

Command Mode

EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

In normal operation, the FDDI interface is operational once the interface is connected and configured. The cmt connect command allows the operator to start the processes that perform the CMT function.

Examples

The following examples demonstrate use of the cmt connect command for starting the CMT processes on the FDDI ring.

The following command starts all FDDI interfaces:

cmt connect

The following command starts both fibers on the FDDI interface unit 0:

cmt connect fddi 0

The following command on the Cisco 7200 series or Cisco 7500 series starts both fibers on the FDDI interface unit 0:

cmt connect fddi 1/0

The following command starts only Physical Sublayer A on the FDDI interface unit 0:

cmt connect fddi 0 phy-a

The following command on Cisco 7500 series routers starts only Physical Sublayer A on the FDDI interface unit 0:

cmt connect fddi 1/0 phy-a

cmt disconnect

Use the cmt disconnect EXEC command to stop the processes that perform the connection management (CMT) function and allow the ring on one fiber to be stopped.

Syntax Description

Command Mode

EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

In normal operation, the FDDI interface is operational once the interface is connected and configured, and is turned off using the shutdown interface configuration command. The cmt disconnect command allows the operator to stop the processes that perform the CMT function and allow the ring on one fiber to be stopped.

The cmt disconnect command is not needed in the normal operation of FDDI; this command is used mainly in interoperability tests.

Examples

The following examples demonstrate use of the cmt disconnect command for stopping the CMT processes on the FDDI ring.

The following command stops all FDDI interfaces:

cmt disconnect

The following command stops both fibers on the FDDI interface unit 0:

cmt disconnect fddi 0

The following command on the Cisco 7200 series or Cisco 7500 series stops both fibers on the FDDI interface unit zero:

cmt disconnect fddi 1/0

The following command stops only Physical Sublayer A on the FDDI interface unit 0. This command causes the FDDI media to go into a wrapped state so that the ring will be broken.

cmt disconnect fddi 0 phy-a

The following command on the Cisco 7500 series stops only Physical Sublayer A on the FDDI interface unit 0 in slot 1. This command causes the FDDI media to go into a wrapped state so that the ring will be broken.

cmt disconnect fddi 1/0 phy-a

compress

To configure compression for Link Access Procedure, Balanced (LAPB), Point-to-Point Protocol (PPP), and High-Level Data Link Control (HDLC) encapsulations, use the compress interface configuration command. On Cisco 7200 series routers and Cisco 7500 series routers, hardware compression on the compression service adapter (CSA) is supported for PPP links. To disable compression, use the no form of this command.

Syntax Description

Default

Compression is disabled.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0 (as compress predictor). The command compress {predictor | stac} first appeared in Cisco IOS Release 10.3.

This command was modified in Cisco IOS Release 11.3 P to include the distributed, software, and csa keywords.

Using CSA hardware compression on Cisco 7200 series routers and Cisco 7500 series routers removes the compression and decompression responsibilities from the VIP2 or the main processor installed in the router. By using the compress stac command, the router determines the fastest compression method available on the router.

When using hardware compression on Cisco 7200 series routers with multiple CSAs, you can optionally specify which CSA is used by the interface to perform compression. If no CSA is specified, the router determines which CSA is used. On Cisco 7500 series routers, the router uses the CSA on the same VIP2 as the interface.

You can configure point-to-point software compression for all LAPB, PPP, and HDLC encapsulations. Compression reduces the size of frames via lossless data compression. HDLC encapsulations supports the Stacker compression algorithm. PPP and LAPB encapsulations support both predictor and Stacker compression algorithms.

Table 26 provides general guidelines for deciding which compression type to select.

Software compression makes heavy demands on the router's processor. The maximum compressed serial line rate depends on the type of Cisco router you are using and which compression algorithm you specify. Table 27 shows a summary of the compressed serial line rates for software compression. The maximums shown in Table 27 apply to the "combined" serial compressed load on the router. For example, a Cisco 4000 series router could handle four 64-kbps lines using Stacker or one 256-kbps line. These maximums also assume there is very little processor load on the router aside from compression. Lower these numbers when the router is required to do other processor-intensive tasks.

Hardware compression can support a combined line rate of 16Mbps.

Cisco recommends that you do not adjust the maximum transmission unit (MTU) for the serial interface and the LAPB maximum bits per frame (N1) parameter.

Examples

The following example enables hardware compression and PPP encapsulation on serial interface 3/1/0.

interface serial 3/1/0
 encapsulate ppp
 compress stac

The following example enables predictor compression on serial interface 0 for a LAPB link:

interface serial 0
 encapsulation lapb
 compress predictor

Related Commands

You can use the master indexes or search online to find documentation of related commands.

encapsulation lapb
encapsulation ppp
encapsulation x25
ppp compress
show compress
show processes

controller t3

To configure the Channelized T3 Interface Processor (CT3IP) in Cisco 7500 series routers, use the controller t3 global configuration command.

Syntax Description

Default

No T3 controller is configured.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.3.

This command is used to configure the CT3IP and the 28 T1 channels. After the T1 channels are configured, continue to configure each T1 channel as a serial interface by using the interface serial global configuration command.

Example

In the following example, the CT3IP in slot 3 is configured:

controller t3 3/0/0

Related Commands

You can use the master indexes or search online to find documentation of related commands.

interface serial

copy flash lex

To download an executable image from Flash memory on the core router to the LAN Extender chassis, use the copy flash lex privileged EXEC command.

Syntax Description

Command Mode

Privileged EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

If you attempt to download a version of the software older than what is currently running on the LAN Extender, a warning message is displayed.

Example

The following example copies the executable image namexx to the LAN Extender interface 0:

Router# copy flash lex 0
Name of file to copy? namexx
Address of remote host [255.255.255.255] 
writing namexx !!!!!!!!!!!!!!!!!!!!!!!!!copy complete

Related Commands

You can use the master indexes or search online to find documentation of related commands.

copy tftp lex

copy tftp lex

To download an executable image from a TFTP server to the LAN Extender, use the copy tftp lex privileged EXEC command.

Syntax Description

Command Mode

Privileged EXEC

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

If you attempt to download a version of the software older than what is currently running on the LAN Extender, a warning message is displayed.

Example

The following example copies the file namexx from the TFTP server:

Router# copy tftp lex 0
Address or name of remote host (255.255.255.255]? 131.108.1.111
Name of file to copy? namexx
OK to overwrite software version 1.0 with 1.1 ?[confirm]
Loading namexx from 131.108.13.111!!!!!!!!!!!!!!!!!!!!!!!!!
[OK - 127825/131072 bytes]
Successful download to LAN Extender

crc

To set the length of the cyclic redundancy check (CRC) on a Fast Serial Interface Processor (FSIP) or HSSI Interface Processor (HIP) of the Cisco 7500 series routers or on a 4-port serial adapter of the Cisco 7200 series routers, use the crc interface configuration command. To set the CRC length to 16 bits, use the no form of this command.

Syntax Description

Default

16 bits

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

All interfaces use a 16-bit cyclic redundancy check (CRC) by default, but also support a 32-bit CRC. CRC is an error-checking technique that uses a calculated numeric value to detect errors in transmitted data. The designators 16 and 32 indicate the length (in bits) of the frame check sequence (FCS). A CRC of 32 bits provides more powerful error detection, but adds overhead. Both the sender and receiver must use the same setting.

CRC-16, the most widely used throughout the United States and Europe, is used extensively with wide-area networks (WANs). CRC-32 is specified by IEEE 802 and as an option by some point-to-point transmission standards. It is often used on SMDS networks and LANs.

Example

In the following example, the 32-bit CRC is enabled on serial interface 3/0:

interface serial 3/0
 crc 32

delay

To set a delay value for an interface, use the delay interface configuration command. Use the no form of this command to restore the default delay value.

Syntax Description

Default

Default delay values may be displayed with the EXEC command show interfaces.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Example

The following example sets a 30,000-microsecond delay on serial interface 3:

interface serial 3
 delay 30000

Related Commands

You can use the master indexes or search online to find documentation of related commands.

show interfaces

dce-terminal-timing enable

When running the line at high speeds and long distances, use the dce-terminal-timing enable interface configuration command to prevent phase shifting of the data with respect to the clock. If SCTE is not available from the DTE, use no form of this command, which causes the DCE to use its own clock instead of SCTE from the DTE.

Syntax Description

This command has no keywords or arguments.

Default

DCE uses its own clock.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

On the Cisco 4000 platform, you can specify the serial Network Interface Module timing signal configuration. When the board is operating as a DCE and the DTE provides terminal timing (SCTE or TT), the dce-terminal-timing enable command causes the DCE to use SCTE from the DTE.

Example

The following example prevents phase shifting of the data with respect to the clock:

interface serial 0
 dce-terminal-timing enable

description (controller)

Use the description controller configuration command to add a description to an E1 or T1 controller or the Channelized T3 Interface Processor (CT3IP) in Cisco 7500 series routers. Use the no form of this command to remove the description.

Syntax Description

Default

No description is added.

Command Mode

Controller configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

This command was modified in Cisco IOS Release 11.3 to include the CT3IP controller.

The description command is meant solely as a comment to be put in the configuration to help you remember what certain controllers are used for. The description affects the CT3IP and MIP interfaces only and appears in the output of the show controller t3, show controller e1, show controller t1, and show running-config EXEC commands.

Example

The following example describes a 3174 controller:

controller t1
 description 3174 Controller for test lab

Related Commands

You can use the master indexes or search online to find documentation of related commands.

show controller e1
show controller t1
show controller t3
show running-config

down-when-looped

Use the down-when-looped interface configuration command to configure an interface to inform the system it is down when loopback is detected.

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

This command is valid for HDLC or PPP encapsulation on serial and HSSI interfaces.

Backup Interfaces

When an interface has a backup interface configured, it is often desirable that the backup interface be enabled when the primary interface is either down or in loopback. By default, the backup is only enabled if the primary interface is down. By using the down-when-looped command, the backup interface will also be enabled if the primary interface is in loopback.

Testing an Interface with the Loopback Command

If testing an interface with the loopback command, or by placing the DCE into loopback, down-when-looped should not be configured; otherwise, packets will not be transmitted out the interface that is being tested.

Example

In the following example, interface serial 0 is configured for HDLC encapsulation. It is then configured to let the system know that it is down when in loopback mode.

interface serial0
 encapsulation hdlc
 down-when-looped

Related Commands

You can use the master indexes or search online to find documentation of related commands.

backup interface serial
loopback (interface)

dte-invert-txc

Use the dte-invert-txc interface configuration command to invert the TXC clock signal received from the DCE. Use the no form of this command if the DCE accepts SCTE from the DTE.

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Use this command if the DCE cannot receive SCTE from the DTE, the data is running at high speeds, and the transmission line is long. This prevents phase shifting of the data with respect to the clock.

On the Cisco 4000 series, you can specify the serial Network Processor Module timing signal configuration. When the board is operating as a DTE, the dte-invert-txc command inverts the TXC clock signal it gets from the DCE that the DTE uses to transmit data. If the DCE accepts SCTE from the DTE, use no dte-invert-txc.

Example

The following example inverts the TXC on serial interface 0:

interface serial 0
 dte-invert-txc

early-token-release

To enable early token release on Token Ring interfaces, use the early-token-release interface configuration command. Once enabled, use the no form of this command to disable this feature.

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Early token release is a method whereby the Token Ring interfaces can release the token back onto the ring immediately after transmitting, rather than waiting for the frame to return. This feature helps increase the total bandwidth of the Token Ring.

The Token Ring Interface Processor (TRIP) on the Cisco 7500 series routers and the Token Ring adapters on the Cisco 7200 series routers all support early token release.

Examples

The following example enables the use of early token release on Token Ring interface 1:

interface tokenring 1
 early-token-release

On the Cisco 7500 series, to enable the use of early token release on your Token Ring interface processor in slot 4 on port 1, issue the following configuration commands:

interface tokenring 4/1
 early-token-release

encapsulation

To set the encapsulation method used by the interface, use the encapsulation interface configuration command.

Syntax Description

Default

The default depends on the type of interface. For example, a synchronous serial interface defaults to HDLC.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

To use SLIP or PPP, the router or access server must be configured with an IP routing protocol or with the ip host-routing command. This configuration is done automatically if you are using old-style slip address commands. However, you must configure it manually if you configure SLIP or PPP via the interface async command.

Examples

The following example resets HDLC serial encapsulation on serial interface 1:

interface serial 1
 encapsulation hdlc

The following example enables PPP encapsulation on serial interface 0:

interface serial 0
 encapsulation ppp

Related Commands

You can use the master indexes or search online to find documentation of related commands.

keepalive
ppp
ppp authentication
slip

fddi burst-count

Use the fddi burst-count interface configuration command to allow the FCI card to preallocate buffers to handle bursty FDDI traffic (for example, NFS bursty traffic). Use the no form of this command to revert to the default value.

Syntax Description

Default

3 buffers

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

This command applies to the FCI card only. The microcode software version should not be 128.45 or 128.43.

Example

The following example sets the number of buffers to 5:

interface fddi 0
 fddi burst-count 5

fddi c-min

To set the C-Min timer on the PCM, use the fddi c-min interface configuration command. Use the no form of this command to revert to the default value.

Syntax Description

Default

1600 microseconds

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

This command applies to the processor CMT only. You need extensive knowledge of the PCM state machine to tune this timer. Use this command when you run into PCM interoperability problems.

Example

The following example sets the C-Min timer to 2000 microseconds:

interface fddi 0
 fddi c-min 2000

Related Commands

You can use the master indexes or search online to find documentation of related commands.

fddi tb-min
fddi tl-min-time
fddi t-out

fddi cmt-signal-bits

To control the information transmitted during the connection management (CMT) signaling phase, use the fddi cmt-signal-bits interface configuration command.

Syntax Description

Defaults

The default signal bits for the phy-a and phy-b keywords are as follows:

• phy-a is set to 0x008 (hexadecimal) or 00 0000 1000 (binary). Bits 1 and 2 are set to 00 to select Physical A. Bit 3 is set to 1 to indicate "accept any connection."

• phy-b is set to 0x20c (hexadecimal) or 10 0000 1100 (binary). Bits 1 and 2 are set to 10 to select Physical B. Bit 3 is set to 1 to indicate "accept any connection." Bit 9 is set to 1 to select MAC on output. The normal data flow on FDDI is input on Physical A and output on Physical B.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

If neither the phy-a nor phy-b keyword is specified, the signal bits apply to both physical connections.

Table 28 lists the physical types.

Table 29 lists the duration bits.

Example

The following example sets the CMT signaling phase to signal bits 0x208 on both physical connections:

interface fddi 0
 fddi cmt-signal-bits 208

fddi duplicate-address-check

Use the fddi duplicate-address-check interface configuration command to turn on the duplicate address detection capability on the FDDI. Use the no form of this command to disable this feature.

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

If you use this command, the Cisco IOS software will detect a duplicate address if multiple stations are sharing the same MAC address. If the software finds a duplicate address, it will shut down the interface.

Example

The following example enables duplicate address checking on the FDDI:

interface fddi 0
 fddi duplicate-address-check

fddi encapsulate

Use the fddi encapsulate interface configuration command to specify encapsulating bridge mode on the CSC-C2/FCIT interface card. Use the no form of this command to turn off encapsulation bridging and return the FCIT interface to its translational, nonencapsulating mode.

Syntax Description

This command has no arguments or keywords.

Default

The FDDI interface by default uses the SNAP encapsulation format defined in RFC 1042. It is not necessary to define an encapsulation method for this interface when using the CSC-FCI interface card.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

The no fddi encapsulate command applies only to CSC-C2/FCIT interfaces, because the CSC-FCI interfaces are always in encapsulating bridge mode. The CSC-C2/FCIT interface card fully supports transparent and translational bridging for the following configurations:

• FDDI to FDDI

• FDDI to Ethernet

• FDDI to Token Ring

The command fddi encapsulate puts the CSC-C2/FCIT interface into encapsulation mode when doing bridging. In transparent mode, the FCIT interface interoperates with earlier versions of the CSC-FCI encapsulating interfaces when performing bridging functions on the same ring.

Caution Bridging between dissimilar media presents several problems that can prevent communications from occurring. These problems include bit-order translation (or usage of MAC addresses as data), maximum transfer unit (MTU) differences, frame status differences, and multicast address usage. Some or all of these problems might be present in a multimedia bridged LAN and might prevent communication from taking place. These problems are most prevalent when bridging between Token Rings and Ethernets or between Token Rings and FDDI nets. This is because of the different way Token Ring is implemented by the end nodes.

The following protocols have problems when bridged between Token Ring and other media: Novell IPX, DECnet Phase IV, AppleTalk, VINES, XNS, and IP. Further, the following protocols may have problems when bridged between FDDI and other media: Novell IPX and XNS. We recommend that these protocols be routed whenever possible.

Example

The following example sets FDDI interface 1 on the CSC-C2/FCIT interface card to encapsulating bridge mode:

interface fddi 1
 fddi encapsulate

fddi smt-frames

Use the fddi smt-frames interface configuration command to enable the SMT frame processing capability on the FDDI. Use the no form of this command to disable this feature and prevent the Cisco IOS software from generating or responding to SMT frames.

Syntax Description

This command has no arguments or keywords.

Default

Enabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Use the no form of this command to turn off SMT frame processing for diagnosing purposes. Use the fddi smt-frames command to reenable the feature.

Example

The following example disables SMT frame processing:

interface fddi 0
 no fddi smt-frames

fddi tb-min

Use the fddi tb-min interface configuration command to set the TB-Min timer in the physical connection management (PCM). Use the no form of this command to revert to the default value.

Syntax Description

Default

100 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

This command applies to the processor CMT only. You need extensive knowledge of the PCM state machine to tune this timer. Use this command when you run into PCM interoperability problems.

Example

The following example sets the TB-Min timer to 200 ms:

interface fddi 0
 fddi tb-min 200

Related Commands

You can use the master indexes or search online to find documentation of related commands.

fddi c-min
fddi tl-min-time
fddi t-out

fddi tl-min-time

Use the fddi tl-min-time interface configuration command to control the TL-Min time (the minimum time to transmit a Physical Sublayer, or PHY line state, before advancing to the next physical connection management [PCM] state, as defined by the X3T9.5 specification).

Syntax Description

Default

30 microseconds

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Interoperability tests have shown that some implementations of the FDDI standard need more than 30 microseconds to sense a signal.

Examples

The following example changes the TL-Min time from 30 microseconds to 100 microseconds:

interface fddi 0
 fddi tl-min-time 100

The following example changes the TL-Min time from 30 microseconds to 100 microseconds on a Cisco 7500 series router:

interface fddi 3/0
 fddi tl-min-time 100

Related Commands

You can use the master indexes or search online to find documentation of related commands.

fddi c-min
fddi tl-min-time
fddi t-out

fddi t-out

Use the fddi t-out interface configuration command to set the t-out timer in the physical connection management (PCM). Use the no form of this command to revert to the default value.

Syntax Description

Default

100 ms

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

This command applies to the processor CMT only. You need extensive knowledge of the PCM state machine to tune this timer. Use this command when you run into PCM interoperability problems.

Example

The following example sets the timeout timer to 200 ms:

interface fddi 0
 fddi t-out 200

Related Commands

You can use the master indexes or search online to find documentation of related commands.

fddi c-min
fddi tb-min
fddi tl-min-time

fddi token-rotation-time

Use the fddi token-rotation-time interface configuration command to control ring scheduling during normal operation and to detect and recover from serious ring error situations.

Syntax Description

Default

5000 microseconds

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

The FDDI standard restricts the allowed time to be greater than 4000 microseconds and less than 165,000 microseconds. As defined in the X3T9.5 specification, the value remaining in the TRT is loaded into the token holding timer (THT). Combining the values of these two timers provides the means to determine the amount of bandwidth available for subsequent transmissions.

Examples

The following example sets the rotation time to 24,000 microseconds:

interface fddi 0
 fddi token-rotation-time 24000

The following example sets the rotation time to 24,000 microseconds on a Cisco 7500 series router:

interface fddi 3/0
 fddi token-rotation-time 24000

fddi valid-transmission-time

To recover from a transient ring error, use the fddi valid-transmission-time interface configuration command.

Syntax Description

Default

2,500 microseconds

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Examples

The following example changes the transmission timer interval to 3000 microseconds:

interface fddi 0
 fddi valid-transmission-time 3000

The following example changes the transmission timer interval to 3000 microseconds on a Cisco 7000 or Cisco 7200:

interface fddi 3/0
 fddi valid-transmission-time 3000

fdl

To set the facilities data link exchange standard for the CSU on the AS5200's T1 controllers, enter the fdl controller configuration command. The no form of this command disables this facilities data-link support.

Syntax Description

Default

Disabled

Command Mode

Controller configuration

Usage Guidelines

You must configure this command on both T1 controllers if you want to support the CSU function on each T1 line. However, you must use the same facilities data link exchange standard as your service provider. You can have a different standard configured on each T1 controller.

Example

The following example configures the ANSI T1.403 standard for both T1 controllers:

AS5200(config)# controller t1 0
AS5200(config-controller)# fdl ansi
AS5200(config-controller)# exit
AS5200(config)# controller t1 1
AS5200(config-controller)# fdl ansi

framing

Use the framing controller configuration command to select the frame type for the T1 or E1 data line.

Syntax Description

Defaults

Super frame is the default on a T1 line.

CRC4 frame is the default on an E1 line.

Command Mode

Controller configuration

Usage Guidelines

Use this command in configurations where the router or access server is intended to communicate with T1 or E1 fractional data line. The service provider determines which framing type, either sf, esf, or crc4, is required for your T1/E1 circuit.

Example

The following example selects extended super frame as the T1 frame type:

framing esf

Related Commands

You can use the master indexes or search online to find documentation of related commands.

cablelength
linecode