Syntax Description

access-list-number	Integer from 700 to 799 that you select for the list.
permit	Permits the frame.
deny	Denies the frame.
address mask	48-bit MAC addresses written in dotted triplet form. The ones bits in the mask argument are the bits to be ignored in the address value.

Defaults

No MAC address access lists are established.

Command Modes

Global configuration

Command History

Release	Modification
10.0	This command was introduced.

Related Commands

Command	Description
access-list (type-code-ibm)	Builds type-code access lists.

Syntax Description

access-list-number	User-selectable number between 200 and 299 that identifies the list.
permit	Permits the frame.
deny	Denies the frame.
type-code	16-bit hexadecimal number written with a leading "0x"; for example, 0x6000. You can specify either an Ethernet type code for Ethernet-encapsulated packets, or a DSAP/SSAP pair for 802.3 or 802.5-encapsulated packets.
wild-mask	16-bit hexadecimal number with ones bits that correspond to bits in the type-code argument that should be ignored when making a comparison. (A mask for a DSAP/SSAP pair should always be at least 0x0101 because these two bits are used for purposes other than identifying the SAP codes.)

Defaults

No type-code access lists are built.

Command Modes

Global configuration

Command History

Release	Modification
10.0	This command was introduced.

Usage Guidelines

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

Command	Description
access-list (XNS extended)	Defines an extended XNS access list.
access-list (XNS standard)	Defines a standard XNS access list.

Syntax Description

string

Text that must be present to accept the packet on a protected or working interface. Up to eight alphanumeric characters are accepted.

Defaults

Authentication is disabled.

Command Modes

Interface configuration

Command History

Release	Modification
11.1 CC	This command was introduced.

Usage Guidelines

Use the aps authenticate command to ensure that only valid packets are accepted on the OOB communication channel.

The aps authenticate command must be configured on both the working and protect interfaces.

Examples

The following example enables authentication on POS interface 0 in slot 4:

Router# configure terminal
Router(config)# interface pos 4/0/0
Router(config-if)# aps working 1
Router(config-if)# aps authenticate sanjose
Router(config-if)# exit
Router(config)# exit
Router#

Related Commands

Command	Description
aps protect	Enables a POS interface as a protect interface.
aps working	Configures a POS interface as a working interface.

Syntax Description

circuit-number

Number of the circuit to switch to the protect interface.

Defaults

No circuit is switched.

Command Modes

Interface configuration

Command History

Release	Modification
11.1 CC	This command was introduced.

Usage Guidelines

Use the aps force command to manually switch the interface to a protect interface when you are not using the aps revert command. For example, if you need to change the fiber connection, you can manually force the working interface to switch to the protect interface.

In a one-plus-one (1+1) configuration only, you can use the aps force 0 command to force traffic from the protect interface back onto the working interface.

The aps force command has a higher priority than any of the signal failures or the aps manual command.

The aps force command is configured only on protect interfaces.

Examples

The following example forces the circuit on POS interface 0 in slot 3 (a protect interface) back onto a working interface:

Router# configure terminal
Router(config)# interface pos 3/0/0
Router(config-if)# aps protect 1
Router(config-if)# aps force 1
Router(config-if)# exit
Router(config)# exit
Router#

Related Commands

Command	Description
aps manual	Manually switches a circuit to a protect interface.
aps protect	Enables a POS interface as a protect interface.
aps working	Configures a POS interface as a working interface.

Syntax Description

circuit-number

Number of the circuit to lock out.

Defaults

No lockout exists.

Command Modes

Interface configuration

Command History

Release	Modification
11.1 CC	This command was introduced.

Usage Guidelines

The aps lockout command is configured only on protect interfaces.

Examples

The following example locks out (that is, prevents the circuit from switching to a protect interface in the event that the working circuit becomes unavailable) the POS interface 3/0/0:

Router# configure terminal
Router(config)# interface pos 3/0/0
Router(config-if)# aps protect 1 7.7.7.7
Router(config-if)# aps lockout 1
Router(config-if)# end
Router#

Related Commands

Command	Description
aps protect	Enables a POS interface as a protect interface.
aps working	Configures a POS interface as a working interface.

Caution Configure the working interface before configuring the protect interface to keep the protect interface from becoming the active circuit and disabling the working circuit when it is finally discovered.

Examples

The following example configures circuit 1 on POS interface 5/0/0 as a protect interface for the working interface on the router with the IP address of 7.7.7.7. For information on how to configure the working interface, refer to the aps working command.

Router# configure terminal
Router(config)# interface pos 5/0/0
Router(config-if)# aps protect 1 7.7.7.7
Router(config-if)# end
Router#

Related Commands

Command	Description
aps working	Configures a POS interface as a working interface.

Syntax Description

minutes

Number of minutes until the circuit is switched back to the working interface after the working interface is available.

Defaults

Automatic switchover is disabled.

Command Modes

Interface configuration

Command History

Release	Modification
11.1 CC	This command was introduced.

Usage Guidelines

Use the aps revert command to return the circuit to the working interface when it becomes available.

The asp revert command is configured only on protect interfaces.

Examples

The following example enables circuit 1 on POS interface 5/0/0 to revert to the working interface after the working interface has been available for 3 minutes:

Router# configure terminal
Router(config)# interface pos 5/0/0
Router(config-if)# aps protect 1 7.7.7.7
Router(config-if)# aps revert 3
Router(config-if)# end
Router#

Related Commands

Command	Description
aps protect	Enables a POS interface as a protect interface.

Syntax Description

seconds1	Number of seconds to wait before sending a hello packet (hello timer).
seconds2	Number of seconds to wait to receive a response from a hello packet before the interface is declared down (hold timer).

Defaults

Hello time is 1 second, and hold time is 3 seconds.

Command Modes

Interface configuration

Command History

Release	Modification
11.1 CC	This command was introduced.

Usage Guidelines

Use the aps timers command to control the time between an automatic switchover from the protect interface to the working interface after the working interface becomes available.

Normally, the hold time is greater than or equal to three times the hello time.

The aps timers command is configured only on protect interfaces.

Examples

The following example specifies a hello time of 2 seconds and a hold time of 6 seconds on circuit 1 on POS interface 5/0/0:

Router# configure terminal
Router(config)# interface pos 5/0/0
Router(config-if)# aps working 1
Router(config-if)# aps timers 2 6
Router(config-if)# end
Router#

Syntax Description

This command has no arguments or keywords.

Defaults

Bidirectional mode.

Command Modes

Interface configuration

Command History

Release	Modification
11.1 CC	This command was introduced.

Usage Guidelines

Use the aps unidirectional command when you must interoperate with SONET network equipment (ADMs) that supports unidirectional mode.

Note We recommend bidirectional mode when it is supported by the interconnecting SONET equipment. When the protect interface is configured as unidirectional, the working and protect interfaces must cooperate to switch the transmit and receive SONET channel in a bidirectional fashion. This happens automatically when the SONET network equipment is in bidirectional mode.

The aps unidirectional command is configured only on protect interfaces.

Examples

The following example configures POS interface 3/0/0 for unidirectional mode:

Router# configure terminal
Router(config)# interface pos 3/0/0
Router(config-if)# aps unidirectional
Router(config-if)# aps protect 1 7.7.7.7
Router(config-if)# end
Router#

Syntax Description

circuit-number

Circuit number associated with this working interface.

Defaults

No circuit is configured as working.

Command Modes

Interface configuration

Command History

Release	Modification
11.1 CC	This command was introduced.

Usage Guidelines

To enable the circuit on the protect interface to switch back to the working interface after the working interface becomes available again, use the aps revert interface configuration command.

Caution Configure the working interface before configuring the protect interface to keep the protect interface from becoming the active circuit and disabling the working circuit when it is finally discovered.

Examples

The following example configures the POS interface 0 in slot 4 as a working interface. For information on how to configure the protect interface, refer to the aps protect command.

Router# configure terminal
Router(config)# interface pos 4/0/0
Router(config-if)# aps working 1
Router(config-if)# end
Router#

Related Commands

Command	Description
aps protect	Enables a POS interface as a protect interface.
aps revert	Enables automatic switchover from the protect interface to the working interface after the working interface becomes available.

Syntax Description

stm-4

(Optional) Synchronous Digital Hierarchy/Synchronous Transport Signal level 4 (SDH/STM-4) operation (ITU-T specification).

Defaults

STS-12c

Command Modes

Interface configuration

Command History

Release	Modification
11.1 CC	This command was introduced.
11.2 GS	The stm-4 keyword was added.

Usage Guidelines

Use STM-4 in applications where SDH framing is required.

Use the default (STS-12c) in applications where the ATM switch requires "unassigned cells" for rate adaptation. An unassigned cell contains 32 zeros.

Examples

The following example sets the mode of operation to SONET STM-4 on ATM interface 3/0:

Router(config)# interface atm 3/0
Router(config-if)# atm sonet stm-4
Router(config-if)# end
Router# 

Syntax Description

This command has no arguments or keywords.

Defaults

Enabled

Command Modes

Hub configuration

Command History

Release	Modification
10.3	This command was introduced.

Usage Guidelines

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

Examples

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

Router(config)# hub ethernet 0 1 3
Router(config-hub)#  auto-polarity

Related Commands

Command	Description
hub	Enables and configures a port on an Ethernet hub of a Cisco 2505 or Cisco 2507 router.

IGRP uses the minimum path bandwidth to determine a routing metric. The TCP protocol adjusts initial retransmission parameters based on the apparent bandwidth of the outgoing interface.

At higher bandwidths, the value you configure with the bandwidth command is not what is displayed by the show interface command. The value shown is that used in IGRP updates and also used in computing load.

Note This is a routing parameter only; it does not affect the physical interface.

Examples

The following example sets the full bandwidth for DS3 transmissions:

Router(config)# interface serial 0
Router(config-if)#  bandwidth 44736

Related Commands

Command	Description
vines metric	Enables VINES routing on an interface.

Syntax Description

feet	Number of feet in the range of 0 to 450. The default values are: 224 feet for Channelized T3 Interface Processor (CT3IP) 49 feet for PA-T3 and PA-2T3 port adapters

Defaults

224 feet for CT3IP interface processor.

49 feet for PA-T3 and PA-2T3 port adapters.

Command Modes

Controller configuration

Command History

Release	Modification
11.1 CA	This command was introduced.

Usage Guidelines

The default cable length of 49 feet is used by the PA-T3 and PA-2T3.

Note Although you can specify a cable length from 0 to 450 feet, the hardware only recognizes two ranges: 0 to 49 and 50 to 450. For example, entering 35 feet uses the 0 to 49 range. If you later change the cable length to 40 feet, there is no change because 40 is within the 0 to 49 range. However, if you change the cable length to 50, the 50 to 450 range is used. The actual number you enter is stored in the configuration file.

Examples

The following example sets the cable length for the router to 300 feet:

Router(config)# controller t3 9/0/0
Router(config-controller)#  cablelength 300

Syntax Description

dbgain-value	Number of decibels by which the receiver signal is increased. Use one of the following values: gain26 gain36 The default is 26db.
dbloss-value	Number of decibels by which the transmit signal is decreased. Use one of the following values: 0db -7.5db -15db -22.5db The default is 0db.

Defaults

Gain of 26db, and transmitter loss of 0db.

Command Modes

Controller configuration for the Cisco AS5200 access server, Cisco AS5800 universal access server, and Cisco MC3810 multiservice access concentrator.

Interface configuration for the Cisco 2600 and Cisco 3600 series routers.

Command History

Release	Modification
11.2	This command was introduced.
11.3	The following choices were added: gain26, gain36, 0db, -7.5db, -15db, -22.5db.
12.0(5)T and 12.0(5)XK	This command was modified to include support as an ATM interface configuration command for the Cisco 2600 and 3600 series routers and a controller configuration command for the Cisco AS5800 universal access server.

Usage Guidelines

Cisco AS5200 Access Server, Cisco AS5800 Universal Access Server, and Cisco MC3810 Multiservice Access Concentrator

Use this command for configuring the controller T1 interface on the Cisco AS5200 access server, on the Cisco AS5800 universal access server, or on the Cisco MC3810 multiservice access concentrator. The cablelength long command is used to configure DS1 links (meaning, to build CSU/DSU links) when the cable length is no longer than 655 feet.

On the Cisco MC3810, this command is supported on T1 controllers only, and applies to Voice-over-Frame Relay, Voice-over-ATM, and Voice-over-HDLC.

Note On the Cisco MC3810, you cannot use the cablelength long command on a DSX-1 interface only. The cablelength long command can be only used on CSU interfaces.

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.

Cisco 2600 and Cisco 3600 Series Routers

This command is supported on T1 long-haul links only. If you enter the cablelength long command on a DSX-1 (short haul) interface, the command is rejected.

The transmit attenuation value is best obtained by experimentation. If the signal received by the far-end equipment is too strong, reduce the transmit level by entering additional attenuation.

Examples

Cisco AS5200 Access Server, Cisco AS5800 Universal Access Server, and Cisco MC3810 Multiservice Access Concentrator

The following example increases the receiver gain by 26 decibels and decreases the transmitting pulse by 7.5 decibels for a long cable on a Cisco AS5200:

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

The following example increases the receiver gain by 36 decibels and decreases the transmitting pulse by 15 decibels for a long cable on a Cisco AS5800:

AS5800(config)# controller t1 0
AS5800(config-controller)# cablelength long gain36 -15db
 

The following example configures the cable length for controller T1 0 on a Cisco MC3810 to a decibel pulse gain of 36 and a decibel pulse rate of -22.5 decibels:

MC3810(config)# controller t1 0
MC3810(config-controller)# cablelength long gain36 -22.5db
 

Cisco 2600 and Cisco 3600 Series Routers

On a Cisco 2600 or 3600 series router, the following example specifies a pulse gain of 36 and a decibel pulse rate of -7.5 decibels:

Router(config)# interface atm 0/2
Router(config-controller)#  cablelength long gain36 -7.5db
 

Related Commands

Command	Description
cablelength short	Sets a cable length 655 feet or shorter for a DS1 link.

Syntax Description

length

Specifies a cable length. Use one of the following values to specify this value: 133---Specifies a cable length from 0 to 133 feet. 266---Specifies a cable length from 134 to 266 feet. 399---Specifies a cable length from 267 to 399 feet. 533---Specifies a cable length from 400 to 533 feet. 655---Specifies a cable length from 534 to 655 feet.

Defaults

The default is 133 feet for the Cisco AS5200 access server, Cisco AS5800 universal access server, and Cisco MC3810 multiservice access concentrator.

No default value or behavior for the Cisco 2600 and Cisco 3600 series routers.

Command Modes

Controller configuration for the Cisco AS5200 access server, Cisco AS5800 universal access server, and Cisco MC3810 multiservice access concentrator.

Interface configuration for the Cisco 2600 and Cisco 3600 series routers.

Command History

Release	Modification
11.3(2)AA	This command was introduced.
12.0(5)T and 12.0(5)XK	This command was modified to include support as an ATM interface command for the Cisco 2600 and 3600 series routers and a controller configuration command for the Cisco AS5800 universal access server.

Usage Guidelines

Cisco AS5200 Access Server, Cisco AS5800 Universal Access Server, and Cisco MC3810 Multiservice Access Concentrator

On the Cisco MC3810, the cablelength short command is used to configure DSX-1 links when the cable length is 655 feet or less than 655 feet. On the Cisco MC3810, this command is supported on T1 controllers only.

Note On the Cisco MC3810, you cannot enter the cablelength short command on a CSU interface. The cablelength short command can only be used on DSX-1 interfaces.

Cisco 2600 and Cisco 3600 Series Routers

This command is supported on T1 short-haul links only. If you enter the cablelength short command on a long-haul interface, the command is rejected.

Examples

Cisco AS5200 Access Server, Cisco AS5800 Universal Access Server, and Cisco MC3810 Multiservice Access Concentrator

In the following example, the cable length is set to 266 for the T1 controller in slot 0 on dial shelf 0:

Router# configure terminal
Router(config)# controller t1 1/1/0
Router(config-controller)# cablelength short 266
router (config-controller)# exit
Router(config)# exit
Router#
 

Cisco 2600 and Cisco 3600 Series Routers

On a Cisco 2600 or 3600 series router, the following example specifies a cable length from 0 to 133 feet:

Router(config)# interface atm 0/2

Router(config-if)#  cablelength short 133

Related Commands

Command	Description
cablelength long	Increases the pulse of a signal at the receiver and decreases the pulse from the sender using pulse equalization and line build-out.

Syntax Description

seconds

Time, in seconds, to wait for the system to change states. Enter an integer in the range 0 to 60. The default is 2 seconds.

Defaults

The default carrier delay is 2 seconds.

Command Modes

Interface configuration

Command History

Release	Modification
10.1	This command was introduced.

Usage Guidelines

Carrier delay works like this: If a link goes down and comes back up before the carrier delay timer expires, the down state is effectively filtered, and the rest of the software on the switch is not aware that a link-down event occurred. Therefore, a large carrier delay timer results in fewer link-up/link-down events being detected. On the other hand, setting the carrier delay time to 0 means that every link-up/link-down event is detected.

In most environments a lower carrier delay is better than a higher one. The exact value you choose depends on the nature of the link outages you expect to see in your network, and how long you expect those outages to last.

If your data links are subject to short outages, especially if those outages last less than the time it takes for your IP routing to converge, you should set a relatively long carrier delay value to prevent these short outages from causing unnecessary churn in your routing tables.

However, if your outages tend to be longer, then you may want to set a shorter carrier delay so that the outages are detected sooner, and the IP route convergence begins and ends sooner.

Examples

The following example changes the carrier delay to 5 seconds:

Router(config)# interface serial 0
Router(config-if)#  carrier-delay 5

Syntax Description

channel-number

Port-channel number previously assigned to the port-channel interface when using the interface port-channel global configuration command. The range is 1 to 4.

Defaults

No channel group is assigned.

Command Modes

Interface configuration

Command History

Release	Modification
11.1 CA	This command was introduced.

Usage Guidelines

If the Fast Ethernet interface has an IP address assigned, you must disable it before adding the Fast Ethernet interface to the Fast EtherChannel. To disable an existing IP address on the Fast Ethernet interface, use the no ip address interface configuration command.

Up to four Fast Ethernet interfaces can be added to a Fast EtherChannel group.

Caution The port-channel interface is the routed interface. Do not enable Layer 3 addresses on the physical Fast Ethernet interfaces. Do not assign bridge groups on the physical Fast Ethernet interfaces because it creates loops. Also, you must disable spanning tree.

To display information about the Fast EtherChannel, use the show interfaces port-channel EXEC command.

Examples

The following example adds Fast Ethernet 1/0 to the Fast EtherChannel group specified by port-channel 1:

Router(config)# interface port-channel 1
Router(config-if)# ip address 1.1.1.10 255.255.255.0
Router(config)# interface fastethernet 1/0/0
Router(config-if)# channel-group 1

Related Commands

Command	Description
interface port-channel	Specifies a Fast EtherChannel and enters interface configuration mode.
show interfaces port-channel	Displays the information about the Fast EtherChannel on Cisco 7500 series routers and Cisco 7000 series routers with the RSP7000 and RSP7000CI.

Cisco 7500 Series

clear controller lex slot/port [prom]

Cisco 7200 Series and 7500 Series with a Packet over SONET Interface Processor

clear controller lex [type] slot/port

Cisco 7500 Series with Ports on VIP Cards

clear controller lex [type] slot/port-adapter/port

Syntax Description

number	Number of the LAN Extender interface corresponding to the LAN Extender to be rebooted.
prom	(Optional) Forces a reload of the PROM image, regardless of any Flash image.
slot	Number of the slot being configured. Refer to the appropriate hardware manual for slot and port information.
port	Number of the port being configured. Refer to the appropriate hardware manual for slot and port information.
type	(Optional) Specifies the interface type. See Table 4 under the clear counters command for keywords.
port-adapter	Number of the port-adapter being configured. Refer to the appropriate hardware manual for information about port adapter compatibility.

Command Modes

Privileged EXEC

Command History

Release	Modification
10.3	This command was introduced.

Usage Guidelines

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

Cisco 4000 Series or Cisco 7500 Series with a LAN Extender Interface

clear counters [type slot/port] [ethernet | serial]

Cisco 7200 Series and 7500 Series with a Packet over SONET Interface Processor

clear counters [type] slot/port

Cisco 7500 Series with Ports on VIP Cards

clear counters [type] slot/port-adapter/port

Syntax Description

type	(Optional) Specifies the interface type; one of the keywords listed in Table 4.
number	(Optional) Specifies the interface counter displayed with the show interfaces command.
ethernet	(Optional) If the type is lex, you can clear the interface counters on the Ethernet interface.
serial	(Optional) If the type is lex, you can clear the interface counters on the serial interface.
slot	Number of the slot being configured. Refer to the appropriate hardware manual for slot and port information.
port	Number of the port being configured. Refer to the appropriate hardware manual for slot and port information.
port-adapter	Number of the port-adapter being configured. Refer to the appropriate hardware manual for information about port adapter compatibility.

Command Modes

EXEC

Command History

Release	Modification
10.0	This command was introduced.
11.3	The following keywords were added or modified: vg-anylan posi keyword changed to pos

Usage Guidelines

Examples

The following example clears all interface counters:

Router# 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:

Router# clear counters pos 1/0
 

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

Router# clear counters lex 0 serial
 

The following example clears the interface counters on a Fast Etherchannel interface.

Router# clear counter port-channel 1
Clear "show interface" counters on all interfaces [confirm]
%CLEAR-5-COUNTERS: Clear counter on all interfaces by console 1

Related Commands

Command	Description
show interfaces	Displays the statistical information specific to a serial interface.
show interfaces port-channel	Displays the information about the Fast EtherChannel on Cisco 7500 series routers and Cisco 7000 series routers with the RSP7000 and RSP7000CI.

Syntax Description

ethernet	Indicates the hub in front of an Ethernet interface.
number	Hub number to clear, starting with 0. Because there is only one hub, this number is 0.

Command Modes

EXEC

Command History

Release	Modification
10.3	This command was introduced.

Examples

The following example clears hub 0:

Router# clear hub ethernet 0

Related Commands

Command	Description
hub	Enables and configures a port on an Ethernet hub of a Cisco 2505 or Cisco 2507 router.

Syntax Description n

ether	(Optional) Indicates the hub in front of an Ethernet interface.
number	(Optional) Hub number for which to clear counters. Since there is currently only one hub, this number is 0. If you specify the keyword ether, you must specify the number.
port	(Optional) Port number on the hub. On the Cisco 2505 router, port numbers range from 1 to 8. On the Cisco 2507 router, port numbers range from 1 to 16. If a second port number follows, then this port number indicates the beginning of a port range. If you do not specify a port number, counters for all ports are cleared.
end-port	(Optional) Ending port number of a range.

Command Modes

EXEC

Command History

Release	Modification
10.3	This command was introduced.

Examples

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

Router# clear hub counters ether 0

Related Commands

Command	Description
show hub	Displays information about the hub (repeater) on an Ethernet interface of a Cisco 2505 or Cisco 2507 router.

Cisco 7200 Series and Cisco 7500 Series with a Packet OC-3 Interface Processor

clear interface type slot/port

Cisco 7500 Series with Ports on VIP Cards

clear interface type slot/port-adapter/port

Cisco 7500 Series

clear interface type slot/port [:channel-group]

Cisco 7500 Series with a CT3IP

clear interface type slot/port-adapter/port [:t1-channel]

Syntax Description

type	Specifies the interface type; it is one of the keywords listed in Table 5 in the "Usage Guidelines" section.
number	Specifies the port, connector, or interface card number.
name-tag	(Optional) Specifies the logic name to identify the server configuration so that multiple entries of server configuration can be entered. This optional argument is for use with the RLM feature.
slot	Number of the slot being configured. Refer to the appropriate hardware manual for slot and port information.
port	Number of the port being configured. Refer to the appropriate hardware manual for slot and port information.
port-adapter	Number of the port-adapter being configured. Refer to the appropriate hardware manual for information about port adapter compatibility.
:channel-group	(Optional) On Cisco 7500 series routers supporting channelized T1, specifies the channel from 0 to 23. This number is preceded by a colon.
:t1-channel	(Optional) For the CT3IP, the T1 channel is a number between 1 and 28. T1 channels on the CT3IP are numbered 1 to 28 rather than the more traditional zero-based scheme (0 to 27) used with other Cisco products. This numbering scheme ensures consistency with telco numbering schemes for T1 channels within channelized T3 equipment.

Command Modes

EXEC

Command History

Release	Modification
10.0	This command was introduced.
11.3	The following keywords were added or modified: vg-anylan posi keyword changed to pos
12.0(3)T	The following optional argument was added for the RLM feature: name-tag

Usage Guidelines

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

Examples

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

Router# clear interface hssi 1
 

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

Router# clear interface pos 1/0
 

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

Router# clear interface serial 9/0/0:0
 

The following example resets the interface logic on Fast Etherchannel interface 1:

Router# clear interface port-channel 1
 

The following example demonstrates the use of the clear interface command with the RLM feature:

Router# clear interface loopback 1
 
Router#
02:48:52: rlm 1: [State_Up, rx ACTIVE_LINK_BROKEN] over link [10.1.1.1(Loopback1), 10.1.4.1]
02:48:52: rlm 1: link [10.1.1.2(Loopback2), 10.1.4.2] requests activation
02:48:52: rlm 1: link [10.1.1.1(Loopback1), 10.1.4.1] is deactivated
02:48:52: rlm 1: link [10.1.1.1(Loopback1), 10.1.4.1] = socket[10.1.1.1, 10.1.4.1]
02:48:52: rlm 1: [State_Recover, rx USER_SOCKET_OPENED] over link [10.1.1.1(Loopback1), 10.1.4.1] for user RLM_MGR
02:48:52: rlm 1: link [10.1.1.1(Loopback1), 10.1.4.1] is opened
02:48:52: rlm 1: link [10.1.1.1(Loopback1), 10.1.5.1] = socket[10.1.1.1, 10.1.5.1]
02:48:52: rlm 1: [State_Recover, rx USER_SOCKET_OPENED] over link [10.1.1.1(Loopback1), 10.1.5.1] for user RLM_MGR
02:48:52: rlm 1: link [10.1.1.1(Loopback1), 10.1.5.1] is opened
02:48:52: rlm 1: [State_Recover, rx START_ACK] over link [10.1.1.2(Loopback2), 10.1.4.2]
02:48:52: rlm 1: link [10.1.1.2(Loopback2), 10.1.4.2] is activated
02:48:52: rlm 1: [State_Up, rx LINK_OPENED] over link [10.1.1.1(Loopback1), 10.1.4.1]
 
Router# show rlm group 1 status   
RLM Group 1 Status
 User/Port: RLM_MGR/3000 
 Link State: Up         Last Link Status Reported: Up_Recovered
 Next tx TID: 4         Last rx TID: 0
 Server Link Group[r1-server]:
  link [10.1.1.1(Loopback1), 10.1.4.1] = socket[standby, 10.1.1.1, 10.1.4.1]
  link [10.1.1.2(Loopback2), 10.1.4.2] = socket[active, 10.1.1.2, 10.1.4.2]
 Server Link Group[r2-server]:
  link [10.1.1.1(Loopback1), 10.1.5.1] = socket[opening, 10.1.1.1, 10.1.5.1]
  link [10.1.1.2(Loopback2), 10.1.5.2] = socket[opening, 10.1.1.2, 10.1.5.2]
 
Router#
Router#
02:49:52: rlm 1: [State_Up, rx UP_RECOVERED_MIN_TIMEOUT]
02:49:52: rlm 1: link [10.1.1.1(Loopback1), 10.1.4.1] requests activation
02:49:52: rlm 1: [State_Switch, rx SWITCH_ACK] over link [10.1.1.1(Loopback1), 10.1.4.1]
02:49:52: rlm 1: link [10.1.1.2(Loopback2), 10.1.4.2] is deactivated
02:49:52: rlm 1: link [10.1.1.1(Loopback1), 10.1.4.1] is activated
 

Related Commands

Command	Description
interface	Defines the IP addresses of the server, configures an interface type, and enters interface configuration mode.
shutdown (RLM)	Shuts down all of the links under the RLM group.

Command History

Release	Modification
11.2	This command was introduced.

Examples

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

Router# clear interface fastethernet 0
 

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

Router# clear interface fastethernet 1/0
 

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

Router# clear interface fastethernet 1/0/0
 

Syntax Description

dial-shelf	Dial shelf chassis in the Cisco AS5800 access server containing the CT3 interface card.
slot	Location of the CT3 interface card in the dial shelf chassis.
t3-port	T3 port number. The only valid value is 0.
:t1-num	T1 timeslot in the T3 line. The value can be from 1 to 28.
:chan-group	Channel group identifier.

Defaults

No default behavior or values.

Command Modes

EXEC

Command History

Release	Modification
10.0	This command was introduced.

Usage Guidelines

The clear interface serial command clears the interface hardware. To reset the counters for an interface, use the clear counters command with the serial keyword specified. To confirm at the prompt. use the show interfaces serial command.

Examples

The following example clears the interface hardware, disconnecting any active lines:

Router# clear interface serial 1/4/0:2:23
Router#
 

Related Commands

Command	Description
clear counters	Clears the interface counters.
show interfaces	Displays statistics for all interfaces configured on the router or access server.
show interfaces serial	Displays information about a serial interface.

Syntax Description

number

Number of the serial interface.

Command Modes

Privileged EXEC

Command History

Release	Modification
11.2	This command was introduced.

Usage Guidelines

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.

Examples

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

Router# clear service-module serial 0
Router#

Related Commands

Command	Description
clear counters	Clears the interface counters.
test service-module	Performs self-tests on an integrated CSU/DSU serial interface module, such as a 4-wire, 56/64-kbps CSU/DSU.

Syntax Description

bps

Desired clock rate in bits per second: 1200, 2400, 4800, 9600, 19200, 38400, 56000, 64000, 72000, 125000, 148000, 250000, 500000, 800000, 1000000, 1300000, 2000000, 4000000, or 8000000. For the synchronous serial port adapters (PA-8T-V35, PA-8T-X21, PA-8T-232, and PA-4T+), a nonstandard clock rate can be used. You can enter any value from 300 to 8000000 bps. The clock rate you enter is rounded (adjusted), if necessary, to the nearest value your hardware can support except for the following standard rates: 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 56000, 64000, 128000, or 2015232. The default is no clock rate configured.

Defaults

No clock rate is configured.

Command Modes

Interface configuration

Command History

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

Usage Guidelines

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 more system:running-config 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:

Router(config)# interface serial 0
Router(config-if)#  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.

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 'more system:running-config' to see the value rounded to.
 
 

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 'more system:running-config' to see the value rounded to.
Router(config-if)# exit
Router(config)#
 

The following example shows how to determine the exact clock rate that the serial interface was rounded to using the more system:running-config command. This example shows only the relevant information displayed by the more system:running-config command; other information was omitted.

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

To configure the clock source of a DS1 link, enter the clock source interface configuration, controller configuration, or ATM interface configuration command. To restore the default line setting, use the no form of this command.

Syntax Description

line	Specifies that the T1/E1 link uses the recovered clock from the line. This is the default.
internal	Specifies that the T1/E1 link uses the internal clock from the interface.
loop-timed	Specifies that the T1/E1 interface takes the clock from the Rx (line) and uses it for Tx.

Defaults

The default value is line.

Command Modes

Interface configuration

Controller configuration for the Cisco MC3810 multiservice access concatenator.

ATM interface configuration for the Cisco 2600 and 3600 series routers.

Command History

Release	Modification
10.3	This command was introduced.
11.1 CA	This command was modified to support the E1-G.703/G.704 serial port adapter, PA-E3 serial port adapters, and Cisco 7200 series routers.
11.3 MA	This command was introduced as a controller configuration command for the Cisco MC3810.
12.0(5)T and 12.0(5)XK	The command was introduced as an ATM interface configuration command for the Cisco 2600 and 3600 series routers.

Usage Guidelines

This command sets clocking for individual T1/E1 links.

Make sure that you specify the clock source correctly for each link, even if you are planning to specify that a certain link will provide clocking for all the links in an IMA group. Because links may be taken in and out of service, requiring that the system select another link for common clocking, any link in an IMA group may provide the common clock.

If the ATM interface is part of an IMA group, you can use the loop-timed keyword to specify that the clock source is the same as the IMA group clock source.

Examples

On a Cisco 2600 or 3600 series router, the following example specifies an internal clock source for the link:

Router(config)# interface atm 0/2
Router(config-if)#  clock source internal
 

Related Commands

Command	Description
ima clock-mode	Sets the transmit clock mode for an ATM IMA group.

Syntax Description

line	Clock source on the active line.
primary	Primary TDM clock source.
secondary	Secondary TDM clock source.
internal	Selects the free running clock (also known as internal clock) as the clock source.

Defaults

The primary TDM clock source is from the T1 0 controller.

The secondary TDM clock source is from the T1 1 controller.

Command Modes

Interface configuration

Command History

Release	Modification
11.2	This command was introduced.

Usage Guidelines

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.

Examples

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:

Router(config)# controller t1 0
Router(config-controller)#  clock source line primary
Router(config)# controller t1 1 
Router(config-controller)#  clock source line secondary

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.

Examples

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
 

The following example specifies the T3 interface to clock its transmitted data from its internal clock:

Router(config)# interface serial 1/0
Router(config-if)#  clock source internal

Related Commands

Command	Description
framing (E1/T1 controller)	Selects the frame type for the T1 or E1 data line.
linecode	Selects the linecode type for T1 or E1 line.

Syntax Description

internal	Specifies that the internal clock source is used. This is the default.
line	Specifies that the network clock source is used.
loop-timed	Decouples the controller clock from the system-wide clock set with the network-clock-select command. The loop-timed clock enables the DVM to connect to a PBX and to connect the MFT to a central office when both the PBX and the central office function as DCE clock sources. This situation assumes that the PBX also takes the clocking from the central office thereby synchronizing the clocks on the DVM and the MFT.

Defaults

The internal clock source is used.

Command Modes

Controller configuration

Command History

Release	Modification
11.3	This command was introduced.

Usage Guidelines

You can also set the clock source for each T1 channel by using the t1 clock source controller configuration command.

Note This command replaces the pos internal-clock command.

Examples

The following example sets the clock source for the CT3IP to line:

Router(config)# controller t3 9/0/0
Router(config-if)#  clock source line

Related Commands

Command	Description
t1 clock source	Specifies where the clock source is obtained for use by each T1 channel on the CT3IP in Cisco 7500 series routers.

Cisco 4000, 7000, 7200, and 7500 Series

clock source {line | internal}

no clock source

Cisco AS5200 and AS5300 Access Servers

clock source {line {primary | secondary} | internal}

no clock source line {primary | secondary}

Syntax Description

line	Specifies that the interface will clock its transmitted data from a clock recovered from the line's receive data stream. This is the default.
internal	Specifies that the interface will clock its transmitted data from its internal clock.
primary	Primary TDM clock source.
secondary	Secondary TDM clock source.

Defaults

Cisco 4000, 7000, 7200, and 7500 Series

The clock source is the line's receive data stream.

Cisco AS5200 and AS5300 Access Servers

The primary TDM clock source is from the T0 controller.

The secondary TDM clock source is from the T1 controller.

Command Modes

Interface configuration

Command History

Release	Modification
10.3	This command was introduced for the Cisco 4000 series, Cisco 7000 series with RSP7000, and Cisco 7500 series routers with the G.703 E1 interface.
11.1 CA	This command was introduced for the TDM bus in a Cisco AS5200 or Cisco AS5300 access server.
11.1 CA	This command was modified to include the E1-G.703/G.704 serial port adapter, PA-E3 serial port adapters, and Cisco 7200 series routers.

Usage Guidelines

Cisco 4000, 7000, 7200, and 7500 Series

Cisco AS5200 and AS5300 Access Servers

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.

Examples

Cisco 4000, 7000, 7200, and 7500 Series

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

Router(config)# interface serial 0/1
Router(config-if)# clock source internal

Cisco AS5200 and AS5300 Access Servers

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

Syntax Description

line	Specifies that the DS1 link uses the recovered clock. The line value is the default clock source used when the Multiflex Trunk (MFT) is installed.
internal	Specifies that the DS1 link uses the internal clock. The internal value is the default clock source used when the Digital Voice Module (DVM) is installed.
loop-timed	Specifies that the T1/E1 controller will take the clock from the Rx (line) and use it for Tx. This setting decouples the controller clock from the system-wide clock set with the network-clock-select command. The loop-timed clock enables the DVM to connect to a PBX and to connect the MFT to a central office when both the PBX and the central office function as DCE clock sources. This situation assumes that the PBX also takes the clocking from the central office thereby synchronizing the clocks on the DVM and the MFT.

Defaults

Line (when the MFT is installed)

Internal (when the DVM is installed)

Command Modes

Controller configuration mode

Command History

Release	Modification
11.1	This command was introduced.

Usage Guidelines

This command applies to Voice-over-Frame Relay, Voice-over-ATM, and Voice-over-HDLC on the Cisco MC3810.

Examples

The following example configures the clock source for the MFT to internal, and the clock source for the DVM for line on a Cisco MC3810 multiservice access concatenator:

Router(config)# controller T1 0
Router(config-controller)#  clock source internal
 
Router(config)# controller T1 1
Router(config-controller)#  clock source line
 

Note You cannot configure the clock source to the line setting for both T1/E1 controllers at the same time.

Syntax Description

fddi	(Optional) Identifies this as a FDDI interface.
port	Number of the port being configured. Refer to the appropriate hardware manual for slot and port information.
slot	Number of the slot being configured. Refer to the appropriate hardware manual for slot and port information.
phy-a	(Optional) Selects Physical Sublayer A.
phy-b	(Optional) Selects Physical Sublayer B.

Defaults

No default behavior or values.

Command Modes

EXEC

Command History

Release	Modification
10.0	This command was introduced.

Usage Guidelines

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

There is not a no form of this command.

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:

Router# cmt connect
 

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

Router# 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:

Router# cmt connect fddi 1/0
 

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

Router# 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:

Router# cmt connect fddi 1/0 phy-a

Syntax Description

fddi	(Optional) Identifies this as a FDDI interface.
port	Number of the port being configured. Refer to the appropriate hardware manual for slot and port information.
slot	Number of the slot being configured. Refer to the appropriate hardware manual for slot and port information.
phy-a	(Optional) Selects Physical Sublayer A.
phy-b	(Optional) Selects Physical Sublayer B.

Defaults

No default behavior or values.

Command Modes

EXEC

Command History

Release	Modification
10.0	This command was introduced.

Usage Guidelines

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.

There is not a no form of this command.

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:

Router# cmt disconnect
 

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

Router# 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:

Router# 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.

Router# 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.

Router# cmt disconnect fddi 1/0 phy-a

Cisco VIP2 Cards

compress {predictor | stac [distributed | software]}

Cisco 7200 Series

compress {predictor | stac [ csa slot | software]}

PPP Encapsulation

compress [predictor | stac | mppc [ignore-pfc]]

Syntax Description

predictor	Specifies that a predictor (RAND) compression algorithm will be used on LAPB and PPP encapsulation. Compression is implemented in the software installed in the router's main processor.
stac	Specifies that a Stacker (LZS) compression algorithm will be used on LAPB, HDLC, and PPP encapsulation. For all platforms except Cisco  7200 series and platforms that support the VIP2, compression is implemented in the software installed in the router's main processor. On Cisco 7200 series, on VIP2s in Cisco 7500 series specifying the compress stac command with no options causes the router to use the fastest available compression method for PPP encapsulation only: If the router contains a compression service adapter (CSA), compression is performed in the CSA hardware (hardware compression). If the CSA is not available, compression is performed in the software installed on the VIP2 (distributed compression). If the VIP2 is not available, compression is performed in the router's main processor (software compression).
distributed	(Optional) Specifies that compression is implemented in the software that is installed in a VIP2. If the VIP2 is not available, compression is performed in the router's main processor (software compression).
software	(Optional) Specifies that compression is implemented in the Cisco IOS software installed in the router's main processor.
csa slot	(Optional) Specifies the CSA to use for a particular interface. This option applies only to Cisco 7200 series routers.
mppc	(Optional) Specifies that the MPPC compression algorithm will be used.
ignore-pfc	(Optional) Specifies that the protocol field compression flag negotiated through LCP will be ignored.

Defaults

Compression is disabled.

Command Modes

Interface configuration

Command History

Release	Modification
10.3	This command was introduced.
11.3 P	The following keywords were added: distributed software csa slot
11.3 T	The following keywords were added: mppc ignore-pfc

Note This command replaces the compress predictor command.

Usage Guidelines

End-point devices must be configured to use the same compression method (predictor, Stacker or MPPC).

MPPC Compression

Point-to-Point Compression

HDLC Encapsulations

For HDLC encapsulations, you can specify a Stacker compression algorithm by using the stac keyword. PPP and LAPB encapsulations support both predictor and Stacker compression algorithms.

Public Data Network Connections

Compression requires that both ends of the serial link be configured to use compression. You should never enable compression for connections to a public data network.

Cisco 7200 and 7500 Series

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.

System Performance

Caution When compression is performed in software installed in the router's main processor, it might significantly affect system performance. We recommend that you disable compression if the CPU load exceeds 40 percent. To display the CPU load, use the show process cpu EXEC command.

If the majority of your traffic is already compressed files, we recommend that you not use compression. If the files are already compressed, the additional processing time spent in attempting unsuccessfully to compress them again will slow system performance.

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

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.

Note The best performance data compression algorithms adjust their compression methodology as they identify patterns in the data. To prevent data loss and support this adjustment process, the compression algorithm is run over LAPB to ensure that everything is sent in order, with no missing data and no duplicate data.

Note For information on configuring Frame Relay compression, refer to the "Configuring Frame Relay" chapter in the Cisco IOS Wide-Area Networking Configuration Guide.

Examples

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

Router(config)# interface serial 3/1/0
Router(config-if)#  encapsulate ppp
Router(config-if)#  compress stac
 

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

Router(config)# interface serial 0
Router(config-if)#  encapsulation lapb
Router(config-if)#  compress predictor
Router(config-if)#  mtu 1509
Router(config-if)#  lapb n1 12072
 

The following example enables Stacker compression on serial interface 0 for a LAPB link. This example does not set the MTU size and the maximum bits per frame (N1); we recommend that you do not change those LAPB parameters for Stacker compression:

Router(config)# interface serial 0
Router(config-if)#  encapsulation lapb
Router(config-if)#  compress predictor
 

The following example configures BRI interface 0 to perform MPPC:

Router(config)# interface BRI0
Router(config-if)#  ip unnumbered ethernet0
Router(config-if)#  encapsulation ppp
Router(config-if)#  isdn spid1 5551234
Router(config-if)#  dialer map ip 172.21.71.74 5551234
Router(config-if)#  dialer-group 1
Router(config-if)#  compress mppc
 

The following example configures asynchronous interface 1 to implement MPPC and ignore the protocol field compression flag negotiated by LCP:

Router(config)# interface async1
Router(config-if)#  ip unnumbered ethernet0
Router(config-if)#  encapsulation ppp
Router(config-if)#  async default routing
Router(config-if)#  async dynamic routing
Router(config-if)#  async mode interactive
Router(config-if)#  peer default ip address 172.21.71.74
Router(config-if)#  compress mppc ignore-pfc
 

Related Commands

Command	Description
encapsulation	Sets encapsulation method used by the interface.
encapsulation x25	Specifies operation of a serial interface as an X.25 device.
exec	Allows an EXEC process on a line.
show compress	Displays compression statistics.
show processes	Displays information about the active processes.

Syntax Description

dial-shelf	Dial shelf chassis in the Cisco AS5800 access server containing the CT3 interface card.
slot	Location of the CT3 interface card in the dial shelf chassis.
t3-port	T3 port number. The only valid value is 0.
:t1-num	T1 timeslot in the T3 line. The value can be from 1 to 28.

Defaults

No default behavior or values.

Command Modes

Global configuration

Command History

Release	Modification
11.3(5)AAA	This command was introduced.

Examples

The following example configures the T1 controller in shelf 1, slot 0, port 0:

Router(config)# controller T1 1/0/0
Router(config-controller)#
 

Related Commands

Command	Description
show controllers t1	Displays information about the T1 links.

Cisco AS5800 Access Server

No default values or behaviors.

Command Modes

Global configuration

Command History

Release	Modification
11.3	This command was introduced.
12.0(3)T	This command was modified to include support for the Cisco AS5800 access server.

Usage Guidelines

Examples

Cisco 7500 Series

The following example configures the CT3IP in slot 3:

Router(config)# controller t3 3/0/0

Cisco AS5800 Access Server

The following example shows the status of the T1 controllers connected to the Cisco AS5800:

Router# show controller T1
T1 1/0/0:1 is up.
 No alarms detected.
 Framing is ESF, Line Code is AMI, Clock Source is Line.
 Data in current interval (770 seconds elapsed):
     5 Line Code Violations, 8 Path Code Violations
     0 Slip Secs, 0 Fr Loss Secs, 7 Line Err Secs, 0 Degraded Mins
     0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 7 Unavail Secs
 Total Data (last 81 15 minute intervals):
     7 Line Code Violations, 4 Path Code Violations,
     6 Slip Secs, 20 Fr Loss Secs, 2 Line Err Secs, 0 Degraded Mins,
     0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 2 Unavail Secs
T1 1/0/1:5 is down.
 Transmitter is sending remote alarm.
 Receiver has loss of frame.
 Framing is SF, Line Code is AMI, Clock Source is Line.
 Data in current interval (770 seconds elapsed):
     50 Line Code Violations, 5 Path Code Violations
     0 Slip Secs, 7 Fr Loss Secs, 7 Line Err Secs, 0 Degraded Mins
     0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 7 Unavail Secs
 Total Data (last 81 15 minute intervals):
     27 Line Code Violations, 22 Path Code Violations,
     0 Slip Secs, 13 Fr Loss Secs, 13 Line Err Secs, 0 Degraded Mins,
     0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 13 Unavail Secs
Router#
 

Related Commands

Command	Description
controller t1	Configures a T1 controller.
interface serial	Specifies a serial interface created on a channelized E1 or channelized T1 controller (for ISDN PRI, CAS, or robbed-bit signaling).

Syntax Description

number

Number of the LAN Extender interface to which to download an image from Flash memory.

Defaults

No default behavior or values.

Command Modes

Privileged EXEC

Command History

Release	Modification
10.3	This command was introduced.

Usage Guidelines

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.

There is not a no form of this command.

Examples

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] <cr>
writing namexx !!!!!!!!!!!!!!!!!!!!!!!!!copy complete

Related Commands

Command	Description
copy tftp lex	Downloads an executable image from a TFTP server to the LAN Extender chassis.

Syntax Description

number

Number of the LAN Extender interface to which to download an image.

Defaults

No default behavior or values.

Command Modes

Privileged EXEC

Command History

Release	Modification
10.3	This command was introduced.

Usage Guidelines

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.

There is not a no form of this command.

Examples

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

Syntax Description

size	CRC size (16 or 32 bits). The default is 16 bits.

Defaults

16 bits

Command Modes

Interface configuration

Command History

Release	Modification
10.0	This command was introduced.

Usage Guidelines

All interfaces use a 16-bit 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 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.

Examples

The following example enables the 32-bit CRC on serial interface 3/0:

Router(config)# interface serial 3/0
Router(config-if)#  crc 32

Syntax Description

This command has no arguments or keywords.

Defaults

Disabled

Command Modes

Interface configuration

Command History

Release	Modification
10.3	This command was introduced.
11.1 CA	This command was modified to include the Cisco 7200 series router and the E1-G.703/G.704 serial port adapter

Usage Guidelines

This command is useful for checking data integrity while operating in framed mode. CRC4 provides additional protection for a frame alignment signal under noisy conditions. For data transmission at E1 (2.048 Mbps), the G.704 standard suggests 4 bits CRC. Refer to CCITT Recommendation G.704 for a definition of CRC4.

You can also use the crc command to set the CRC size for the HDLC controllers.

Examples

The following example enables CRC4 generation on the E1-G.703/G.704 serial port adapter and also sets the CRC size to 32 bits:

Router(config)# interface serial 0/0
Router(config-if)#  crc 32
Router(config-if)#  crc4
 

Syntax Description

This command has no arguments or keywords.

Defaults

The default is no CRC5 checking.

Command Modes

Interface configuration

Command History

Release	Modification
11.1 CA	This command was introduced.

Usage Guidelines

This command is available for the JT2 6.3-MHz serial port adapter (PA-2JT2) on second-generation Versatile Interface Processor (VIP2), in Cisco 7500 series routers, and in Cisco 7000 series routers with the Cisco 7000 series Route Switch Processor (RSP7000) and Cisco 7000 series Chassis Interface (RSP7000CI).

This command is useful for checking data integrity while operating in framed mode. CRC5 provides additional protection for a frame alignment signal under noisy conditions. For data transmission at JT2 (6.312 Mbps), the G.704 standard suggests 5 bits CRC. Refer to ITU Recommendation G.704 for a definition of CRC5.

You can also use the crc command to set the CRC size for the HDLC controllers.

Examples

The following example enables CRC 5 generation on the PA-2JT2 port adapter and also sets the CRC size to 32 bits:

Router(config)# interface serial 0/0
Router(config-if)#  crc 32
Router(config-if)#  crc bits 5