-
Cisco IOS Interface Command Reference, Release 12.2
-
About the Cisco IOS Software Documentation
-
Using Cisco IOS Software
-
Interface Commands - Introduction
-
Interface Commands (aps-authenticate - cut-through)
-
Interface Commands (dce-terminal-timing enable - interface)
-
Interface Commands (interface fastethernet - loopback line)
-
Interface Commands (loopback remote - service module t1 remote-loopback)
-
Interface Commands (service-module t1 timeslots - show hub)
-
Interface Commands (show interfaces - show interfaces vg-anylan)
-
Interface Commands (show pas caim - tx-queue-limit)
-
Dial Shelf Management Commands
-
Online index for Cisco IOS Interface Comand Reference
-
Feedback
Table Of Contents
channel-group (Fast EtherChannel)
Interface Commands
This book describes the basic 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:
Other interface commands, specific to a particular technology area, are described in the technology specific configuration guides. For example, 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.
aps authenticate
To enable authentication and specify the string that must be present to accept any packet on the out-of-band (OOB) communications channel on a packet-over-SONET (POS) interface, use the aps authenticate command ininterface configuration mode. To disable authentication, use the no form of this command.
aps authenticate string
no aps authenticate
Syntax Description
string
Text that must be present to accept the packet on a protected or working interface. A maximum of eight alphanumeric characters are accepted.
Defaults
Authentication is disabled.
Command Modes
Interface configuration
Command History
Usage Guidelines
Use the aps authenticate command to ensure that only valid packets are accepted on the OOB communications 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 terminalRouter(config)# interface pos 4/0/0Router(config-if)# aps working 1Router(config-if)# aps authenticate sanjoseRouter(config-if)# exitRouter(config)# exitRouter#Related Commands
Enables a POS interface as a protect interface.
Configures a POS interface as a working interface.
aps force
To manually switch the specified circuit to a protect interface, unless a request of equal or higher priority is in effect, use the aps force command in interface configuration mode. To cancel the switch, use the no form of this command.
aps force circuit-number
no aps force circuit-number
Syntax Description
Defaults
No circuit is switched.
Command Modes
Interface configuration
Command History
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 terminalRouter(config)# interface pos 3/0/0Router(config-if)# aps protect 10/30/1/1Router(config-if)# aps force 1Router(config-if)# exitRouter(config)# exitRouter#Related Commands
Manually switches a circuit to a protect interface.
Enables a POS interface as a protect interface.
Configures a POS interface as a working interface.
aps group
To allow more than one protect and working interface to be supported on a router, use the aps group command in interface configuration mode. To remove a group, use the no form of this command.
aps group group-number
no aps group group-number
Syntax Description
Defaults
No groups exist.
Note
0 is a valid group number.
The default group-number is 0.
The aps group 0 command does not imply that no groups exist.Command Modes
Interface configuration
Command History
Usage Guidelines
Use the aps group command to specify more than one working and protect interfaces on a router, for example, working channel for group 0 and protect channel for group 1 on one router, and working channel for group 1 and protect channel for group 0 on another router.
The aps group command must be configured on both the protect and working interfaces.
Examples
The following example configures two working/protect interface pairs. Working interface (3/0/0) is configured in group 10 (the protect interface for this working interface is configured on another router), and protect interface (2/0/1) is configured in group 20:
Router# configure terminalRouter(config)# interface ethernet 0/0Router(config-if)# ip address 10.7.7.6 255.255.255.0Router(config-if)# exitRouter(config)# interface pos 3/0/0Router(config-if)# aps group 10Router(config-if)# aps working 1Router(config-if)# exitRouter(config)# interface pos 2/0/1Router(config-if)# aps group 20Router(config-if)# aps protect 1 10.7.7.7Router(config-if)# endOn the second router, protect interface (4/0/0) is configured in group 10, and working interface (5/0/0) is configured in group 20 (the protect interface for this working interface is configured on another router):
Router(config)# interface ethernet 0/0Router(config-if)# ip address 7.7.7.7 255.255.255.0Router(config-if)# exitRouter(config)# interface pos 4/0/0Router(config-if)# aps group 10Router(config-if)# aps protect 1 7.7.7.6Router(config-if)# exitRouter(config)# interface pos 5/0/0Router(config-if)# aps group 20Router(config-if)# aps working 1Router(config-if)# exitRouter(config)# endRouter#Related Commands
Enables a POS interface as a protect interface.
Configures a POS interface as a working interface.
aps lockout
To prevent a working interface from switching to a protect interface, use the aps lockout command in interface configuration mode. To remove the lockout, use the no form of this command.
aps lockout circuit-number
no aps lockout circuit-number
Syntax Description
Defaults
No lockout exists.
Command Modes
Interface configuration
Command History
Usage Guidelines
The aps lockout command is configured only on protect interfaces.
Examples
This example locks out POS interface 3/0/0 (that is, prevents the circuit from switching to a protect interface in the event that the working circuit becomes unavailable):
Router# configure terminalRouter(config)# interface pos 3/0/0Router(config-if)# aps protect 1 10.7.7.7Router(config-if)# aps lockout 1Router(config-if)# endRouter#Related Commands
Enables a POS interface as a protect interface.
Configures a POS interface as a working interface.
aps manual
To manually switch a circuit to a protect interface, use the aps manual command in interface configuration mode. To cancel the switch, use the no form of this command.
aps manual circuit-number
no aps manual circuit-number
Syntax Description
Defaults
No circuit is switched.
Command Modes
Interface configuration
Command History
Usage Guidelines
Use the aps manual command to manually switch the interface to a protect interface. For example, you can use this feature when you need to perform maintenance on the working channel. If a protection switch is already up, you can also use the aps manual command to revert the communication link back to the working interface before the wait to restore (WTR) time has expired. The WTR time period is set by the aps revert command.
In a one-plus-one (1+1) configuration only, you can use the aps manual 0 command to force traffic from the protect interface back onto the working interface.
The aps manual command is a lower priority than any of the signal failures or the aps force command.
Examples
The following example forces the circuit on POS interface 0 in slot 3 (a working interface) back onto the protect interface:
Router# configure terminalRouter(config)# interface pos 3/0/0Router(config-if)# aps working 1Router(config-if)# aps manual 1Router(config-if)# endRouter#Related Commands
aps protect
To enable a POS interface as a protect interface, use the aps protect command in interface configuration mode. To remove the POS interface as a protect interface, use the no form of this command.
aps protect circuit-number ip-address
no aps protect circuit-number ip-address
Syntax Description
circuit-number
Number of the circuit to enable as a protect interface.
ip-address
IP address of the router that has the working POS interface.
Defaults
No circuit is protected.
Command Modes
Interface configuration
Command History
Usage Guidelines
Use the aps protect command to configure the POS interface used by a working interface if the working interface becomes unavailable because of a router failure, degradation or loss of channel signal, or manual intervention.
Caution
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 10.7.7.7. For information on how to configure the working interface, refer to the aps working command.
Router# configure terminalRouter(config)# interface pos 5/0/0Router(config-if)# aps protect 1 10.7.7.7Router(config-if)# endRouter#Related Commands
aps revert
To enable automatic switchover from the protect interface to the working interface after the working interface becomes available, use the aps revert command in interface configuration mode. To disable automatic switchover, use the no form of this command.
aps revert minutes
no aps revert
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
Usage Guidelines
Use the aps revert command to return the circuit to the working interface when it becomes available.
The aps 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 terminalRouter(config)# interface pos 5/0/0Router(config-if)# aps protect 1 10.7.7.7Router(config-if)# aps revert 3Router(config-if)# endRouter#Related Commands
aps timers
To change the time between hello packets and the time before the protect interface process declares a working interface router to be down, use the aps timers command in interface configuration mode. To return to the default timers, use the no form of this command.
aps timers seconds1 seconds2
no aps timers
Syntax Description
Defaults
Hello time is 1 second, and hold time is 3 seconds.
Command Modes
Interface configuration
Command History
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 terminalRouter(config)# interface pos 5/0/0Router(config-if)# aps working 1Router(config-if)# aps timers 2 6Router(config-if)# endRouter#aps unidirectional
To configure a protect interface for unidirectional mode, use the aps unidirectional command in interface configuration mode. To return to the default, bidirectional mode, use the no form of this command.
aps unidirectional
no aps unidirectional
Syntax Description
This command has no arguments or keywords.
Defaults
Bidirectional mode
Command Modes
Interface configuration
Command History
Usage Guidelines
Use the aps unidirectional command when you must interoperate with SONET network equipment, Add Drop Multiplexor(s) (ADMs) that supports unidirectional mode.
Note
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 terminalRouter(config)# interface pos 3/0/0Router(config-if)# aps unidirectionalRouter(config-if)# aps protect 1 7.7.7.7Router(config-if)# endRouter#aps working
To configure a Packet over SONET (POS) interface as a working interface, use the aps working command in interface configuration mode. To remove the protect option from the POS interface, use the no form of this command.
aps working circuit-number
no aps working circuit-number
Syntax Description
Defaults
No circuit is configured as working.
Command Modes
Interface configuration
Command History
Usage Guidelines
When a working interface becomes unavailable because of a router failure, degradation or loss of channel signal, or manual intervention, the circuit is switched to the protect interface to maintain the connection.
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 command in interface configuration mode.
Caution
Examples
The following example configures 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 terminalRouter(config)# interface pos 4/0/0Router(config-if)# aps working 1Router(config-if)# endRouter#Related Commands
Enables a POS interface as a protect interface.
Enables automatic switchover from the protect interface to the working interface after the working interface becomes available.
atm sonet
To set the mode of operation and thus control the type of the ATM cell used for cell-rate decoupling on the SONET physical layer interface module (PLIM), use the atm sonet command in interface configuration mode. To restore the default Synchronous Transport Signal level 12, concatenated (STS-12c) operation, use the no form of this command.
atm sonet [stm-4]
no atm sonet [stm-4]
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
Usage Guidelines
Use STM-4 in applications in which SDH framing is required.
Use the default (STS-12c) in applications in which 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 3/0Router(config-if)# atm sonet stm-4Router(config-if)# endRouter#auto-polarity
To enable automatic receiver polarity reversal on a hub port connected to an Ethernet interface of a Cisco 2505 or Cisco 2507 router, use the auto-polarity command in hub configuration mode. To disable this feature, use the no form of this command.
auto-polarity
no auto-polarity
Syntax Description
This command has no arguments or keywords.
Defaults
Enabled
Command Modes
Hub configuration
Command History
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 3Router(config-hub)# auto-polarityRelated Commands
Enables and configures a port on an Ethernet hub of a Cisco 2505 or Cisco 2507 router.
bandwidth (interface)
To set and communicate the current bandwidth value for an interface to higher-level protocols, use the bandwidth command in interface configuration mode. To restore the default values, use the no form of this command.
bandwidth kilobits
no bandwidth
Syntax Description
kilobits
Intended bandwidth, in kilobits per second. For a full bandwidth DS3, enter the value 44736.
Defaults
Default bandwidth values are set during startup and can be displayed with the show interface EXEC command.
Command Modes
Interface configuration
Command History
Usage Guidelines
Note
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.
Interior Gateway Routing Protocol (IGRP) uses the minimum path bandwidth to determine a routing metric. The TCP protocol adjusts initial retransmission parameters on the basis of 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
Examples
The following example sets the full bandwidth for DS3 transmissions:
Router(config)# interface serial 0Router(config-if)# bandwidth 44736Related Commands
bert abort
To end a bit error rate testing session, use the bert abort command in privileged EXEC mode.
bert abort
Syntax Description
This command has no arguments or keywords.
Command Modes
Privileged EXEC
Command History
12.0(2)XD
This command was introduced.
12.0(3)T
This command was integrtaed into Cisco IOS Release 12.0(3) T.
Usage Guidelines
Use the bert abort command to cancel bit error rate testing on each port of the Cisco AS5300 router.
The bit error rate test (BERT) feature enables you to test the quality of the connected PRI links by direct comparison of a pseudorandom or repetitive test pattern with an identical locally generated test pattern.
Examples
This sample display shows output for the bert abort command when no bit error rate test is running:
Router# bert abortRouter#17:53:33: There is no BERT Test running ....This sample display shows output from the bert abort command when a bit error rate test is running:
Router# bert abortDo you really want to abort the current BERT [confirm] Y17:56:56: %BERT-6-BERT_RESULTS: Controller T1 0 Profile default : The Test wasaborted by UserRelated Commands
Starts a bit error rate test for a particular port.
Sets up various bit error rate testing profiles.
bert controller
To start a bit error rate test for a particular port, use the bert controller command in privileged EXEC mode.
bert controller [type-controller] {[last-controller] | profile [number | default]}
Syntax Description
Defaults
The default profile number is 0.
Command Modes
Privileged EXEC
Command History
12.0(2)XD
This command was introduced.
12.0(3)T
This command was integrated into Cisco IOS Release 12.0(3)T.
Usage Guidelines
Use the bert controller command to start a bit error rate test for a particular port on a Cisco AS5300 router.
Quality Testing
The bit error rate test (BERT) feature enables you to test the quality of the connected PRI links by direct comparison of a pseudo-random or repetitive test pattern with an identical locally generated test pattern.
E1 Controllers
The E1 controller cannot be set in loopback mode from the AS5300. For the bert controller command to work correctly with the E1 controller, the controller must be configured as a channel-group or CAS and the line must be configured as a remote loop from the switch side of the link.
Examples
This sample display shows output from the bert controller command:
Router# bert controller T1 0 profile 0Press <Return> to start the BERT [confirm] Y17:55:34: %BERT-6-BERT_START: Starting BERT on Interface 0 with Profile defaultData in current interval (10 seconds elapsed):0 Line Code Violations, 0 Path Code Violations0 Slip Secs, 0 Fr Loss Secs, 0 Line Err Secs, 0 Degraded Mins0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 0 Unavail SecsTable 3 describes the significant fields shown in the sample display for the bert controller command.
Related Commands
Aborts a bit error rate testing session.
Sets up various bit error rate testing profiles.
bert pattern
To enable a bit error rate (BER) test pattern on a T1 or E1 line, use the bert pattern command in controller configuration mode. To disable a BER test pattern, use the no form of this command.
bert pattern {2^23 | 2^20 | 2^20-QRSS | 2^15 | 2^11 | 1s | 0s | alt-0-1} interval time
no bert pattern {2^23 | 2^20 | 2^20-QRSS | 2^15 | 2^11 | 1s | 0s | alt-0-1} interval time
Syntax Description
Defaults
Disabled
Command Modes
Controller configuration
Command History
Usage Guidelines
BER testing is supported on each of the T1 or E1 links and is done only over an unframed T1 or E1 signal, run on only one port at a time.
To view the BER test results, use the show controllers atm EXEC command. The BERT results include the following information:
•
•
•
•
•
•
When the T1 or E1 line has a BER test running, the line state is DOWN and the status field shows the current/last result of the test.
The bert pattern command is not written to NVRAM. This command is only used to test the T1 or E1 line for a short predefined interval and to avoid accidentally saving the command, which could cause the interface not to come up the next time the router reboots.
Examples
In the following example on a Cisco 7200 series router, a BER test pattern of all zeros is run for 30 minutes on T1 line 0 on the port adapter in slot 9:
interface atm 9/0bert pattern 0s interval 30Related Commands
bert profile
To set up various bit error rate testing profiles, use the bert profile command in privileged EXEC mode. To disable the particular bit error rate test (BERT) profile indicated by profile number, use the no form of this command.
bert profile number pattern pattern threshold threshold error-injection err_inj duration time
no bert profile number pattern pattern threshold threshold error-injection err_inj duration time
Syntax Description
Defaults
The default profile created internally by the system has parameters that cannot be changed. This profile has been defined so that you can execute BERT on a line without having to configure a new profile. The default profile is displayed when the running configuration is displayed and is not stored in non-volatile random access memory (NVRAM):
bert profile default pattern 220-0151QRSS threshold 10^-6 error-injection none duration 10
Command Modes
Privileged EXEC
Command History
12.0(2)XD
This command was introduced.
12.0(3)T
This command was implemented in Cisco IOS Release 12.0 T.
Usage Guidelines
Use the bert profile command to set up bit error rate testing profiles for the Cisco AS5300 router.
The bit error rate test (BERT) feature enables you to test the quality of the connected PRI links by direct comparison of a pseudorandom or repetitive test pattern with an identical locally generated test pattern. A BERT profile is a set of parameters related to a BERT test and is stored as part of the configuration in the NVRAM. You can define up to 15 BERT profiles on the system. By setting up the BERT profiles in this way, you do not have to enter the parameters each time you want to run a BERT—just select the number of the BERT profile you want to run.
Examples
The following example shows a configured BERT profile number 1 to have a 0s test pattern, with a 10-2 threshold, no error injection, and a duration of 125 minutes:
Router(config)# bert ?profile Profile Number for this BERT configurationRouter(config)# bert profile ?<1-15> BERT Profile NumberRouter(config)# bert profile 1 pattern 0s threshold 10^-2 error-injection none duration 125Related Commands
Aborts a bit error rate testing session.
Starts a bit error rate test for a particular port.
cablelength
To specify the distance of the cable from the routers to the network equipment, use the cablelength command in controller configuration mode. To restore the default cable length, use the no form of this command.
cablelength feet
no cablelength
Syntax Description
feet
Number of feet in the range of 0 to 450. The default values are:
•
•
Defaults
224 feet for CT3IP interface processor
49 feet for PA-T3 and PA-2T3 port adapters
Command Modes
Controller configuration
Command History
Usage Guidelines
The default cable length of 224 feet is used by the CT3IP interface processor.
The default cable length of 49 feet is used by the PA-T3 and PA-2T3port adapters.
Note
Examples
The following example sets the cable length for the router to 300 feet:
Router(config)# controller t3 9/0/0Router(config-controller)# cablelength 300cablelength 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, use the cablelength long command in controller configuration or interface configuration mode. To return the pulse equalization and line build-out values to their default settings, use the no form of this command.
cablelength long dbgain-value dbloss-value
no cablelength long
Syntax Description
Defaults
Receiver gain of 26 dB and transmitter loss of 0 dB.
Command Modes
Controller configuration for the Cisco AS5200 universal 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
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
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 0AS5200(config-controller)# cablelength long gain26 -7.5dbThe 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 0AS5800(config-controller)# cablelength long gain36 -15dbThe following example configures the cable length for controller T1 0 on a Cisco MC3810 to a decibel pulse gain of 36 decibels and a decibel pulse rate of -22.5 decibels:
MC3810(config)# controller t1 0MC3810(config-controller)# cablelength long gain36 -22.5dbCisco 2600 and Cisco 3600 Series Routers
On a Cisco 2600 or 3600 series router, the following example specifies a pulse gain of 36 decibels and a decibel pulse rate of -7.5 decibels:
Router(config)# interface atm 0/2Router(config-controller)# cablelength long gain36 -7.5dbRelated Commands
cablelength short
To set a cable length 655 feet or shorter for a DS1 link on the Cisco MC3810 or Cisco 2600 and 3600 series routers, use the cablelength short command in controller configuration or interface configuration mode. This command is supported on T1 controllers only. To delete the cablelength short value, use the no form of this command. To set cable lengths longer than 655 feet, use the cablelength long command.
cablelength short length
no cablelength short
Syntax Description
Defaults
The default is 133 feet for the Cisco AS5200 access server, Cisco AS5800 universal access server, and Cisco MC3810 multiservice access concentrator.
There is 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
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
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 terminalRouter(config)# controller t1 1/1/0Router(config-controller)# cablelength short 266router (config-controller)# exitRouter(config)# exitRouter#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 0/2Router(config-if)# cablelength short 133
Related Commands
Increases the pulse of a signal at the receiver and decreases the pulse from the sender using pulse equalization and line build-out.
carrier-delay
To set the carrier delay on a serial interface, use the carrier-delay command in interface configuration mode. To return to the default carrier delay value, use the no form of this command.
carrier-delay [seconds |msec milliseconds]
no carrier-delay [seconds | msec milliseconds]
Syntax Description
Defaults
The default carrier delay is 2 seconds; default in milliseconds is 50 milliseconds.
Command Modes
Interface configuration
Command History
Usage Guidelines
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, you might 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 0Router(config-if)# carrier-delay 5channel-group (Fast EtherChannel)
To assign a Fast Ethernet interface to a Fast EtherChannel group, use the channel-group command in interface configuration mode. To remove a Fast Ethernet interface from a Fast EtherChannel group, use the no form of this command.
channel-group channel-number
no channel-group channel-number
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 configured.
Command Modes
Interface configuration
Command History
Usage Guidelines
Before you assign a Fast Ethernet interface to a Fast EtherChannel group, you must first create a port-channel interface. To create a port-channel interface, use the interface port-channel global configuration command.
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 command in interface configuration mode.
The Fast EtherChannel feature allows multiple Fast Ethernet point-to-point links to be bundled into one logical link to provide bidirectional bandwidth of up to 800 Mbps. Fast EtherChannel can be configured between Cisco 7500 series routers and Cisco 7000 series routers with the 7000 Series Route Switch Processor (RSP7000) and 7000 Series Chassis Interface (RSP7000CI) or between a Cisco 7500 series router or a Cisco 7000 series router with the RSP7000 and RSP700CI and a Catalyst 5000 switch.
A maximum of four Fast Ethernet interfaces can be added to a Fast EtherChannel group.
Caution
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 1Router(config-if)# ip address 1.1.1.10 255.255.255.0Router(config)# interface fastethernet 1/0/0Related Commands
clear aim
To clear the data compression Advanced Interface Module (AIM) daughter card registers and reset the hardware, use the clear aim command in privileged EXEC mode.
clear aim element-number
Syntax Description
Command Modes
Privileged EXEC
Command History
Usage Guidelines
The clear aim command is used to reset the data compression AIM hardware. This command is used if the compression Advanced Interface Module (CAIM) hardware becomes "stuck" or hangs for some reason. The CAIM registers are cleared, and the hardware is reset upon execution. All compression history is lost when the CAIM is reset.
This command is supported only on Cisco 2600 series routers.
Examples
The following example shows how to use the clear aim command. This command will reset the hardware, flushing the buffers and history for all compression tasks currently under operation:
Router# clear aim 0Router#1w0d: %CAIM-6-SHUTDOWN: CompressionAim0 shutting down1w0d: %CAIM-6-STARTUP: CompressionAim0 starting upRelated Commands
Displays the IDPROM contents for each AIM board in the Cisco 2600 series routers.
Tests the data compression AIM after it is installed in a Cisco 2600 series router.
clear controller
To reset the T1 or E1 controller, use the clear controller command in EXEC mode.
Cisco 7200 Series and Cisco 7500 Series Routers
clear controller {t1 | e1} slot/port
Cisco AS5200 Series and Cisco AS5300 Series Routers
clear controller {t1 | e1} number
Syntax Description
Command Modes
EXEC
Command History
Examples
The following example resets the T1 controller at slot 4, port 0 on a Cisco 7500 series router:
Router# clear controller t1 4/0The following example resets the E1 controller at NIM 0:
Router# clear controller e1 0Related Commands
clear controller lex
To reboot the LAN Extender chassis and restart its operating software, use the clear controller lex command in privileged EXEC mode.
clear controller lex number [prom]
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
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 2reload remote lex controller? [confirm] yesThe 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 promreload remote lex controller? [confirm] yesclear counters
To clear the interface counters, use the clear counters command in user EXEC mode.
clear counters [type number]
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
10.0
This command was introduced.
11.2 F
The virtual-access keyword was added.
11.3
The following keywords were added or modified:
•
•
Usage Guidelines
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 4 lists the command keywords and their descriptions.
Note
Examples
The following example clears all interface counters:
Router# clear countersThe 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 1/0The following example clears the interface counters on a Fast EtherChannel interface.
Router# clear counter port-channel 1Clear "show interface" counters on all interfaces [confirm] Y%CLEAR-5-COUNTERS: Clear counter on all interfaces by console 1Related Commands
clear hub
To reset and reinitialize the hub hardware connected to an interface of a Cisco 2505 or Cisco 2507 router, use the clear hub command in EXEC mode.
clear hub ethernet number
Syntax Description
ethernet
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
Examples
The following example clears hub 0:
Router# clear hub ethernet 0Related Commands
Enables and configures a port on an Ethernet hub of a Cisco 2505 or Cisco 2507 router.
clear hub counters
To set to zero the hub counters on an interface of a Cisco 2505 or Cisco 2507 router, use the clear hub counters command in EXEC mode.
clear hub counters [ether number [port [end-port]]]
Syntax Descriptionn
Command Modes
EXEC
Command History
Examples
The following example clears the counters displayed in a show hub command for all ports on hub 0:
Router# clear hub counters ether 0Related Commands
Displays information about the hub (repeater) on an Ethernet interface of a Cisco 2505 or Cisco 2507 router.
clear interface
To reset the hardware logic on an interface, use the clear interface command in EXEC mode.
clear interface type number [name-tag]
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
Interface type; it is one of the keywords listed in Table 5.
number
Port, connector, or interface card number.
name-tag
(Optional) 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
Usage Guidelines
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 5 lists the command keywords and their descriptions.
Examples
The following example resets the interface logic on HSSI interface 1:
Router# clear interface hssi 1The following example resets the interface logic on Packet OC-3 interface 0 on the POSIP in slot 1:
Router# clear interface pos 1/0The following example resets the interface logic on T1 0 on the CT3IP in slot 9:
Router# clear interface serial 9/0/0:0The following example resets the interface logic on Fast Etherchannel interface 1:
Router# clear interface port-channel 1The following example demonstrates the use of the clear interface command with the RLM feature:
Router# clear interface loopback 1Router#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 activation02:48:52: rlm 1: link [10.1.1.1(Loopback1), 10.1.4.1] is deactivated02:48:52: 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_MGR02:48:52: rlm 1: link [10.1.1.1(Loopback1), 10.1.4.1] is opened02:48:52: 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_MGR02:48:52: rlm 1: link [10.1.1.1(Loopback1), 10.1.5.1] is opened02:48:52: 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 activated02:48:52: rlm 1: [State_Up, rx LINK_OPENED] over link [10.1.1.1(Loopback1), 10.1.4.1]Router# show rlm group 1 statusRLM Group 1 StatusUser/Port: RLM_MGR/3000Link State: Up Last Link Status Reported: Up_RecoveredNext tx TID: 4 Last rx TID: 0Server 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 activation02:49:52: 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 deactivated02:49:52: rlm 1: link [10.1.1.1(Loopback1), 10.1.4.1] is activatedRelated Commands
clear interface fastethernet
To reset the controller for a specified Fast Ethernet interface, use the clear interface fastethernet command in privileged EXEC mode.
Cisco 4500 and 4700 series
clear interface fastethernet number
Cisco 7200 and 7500 series
clear interface fastethernet slot/port
Cisco 7500 series
clear interface fastethernet slot/port-adapter/port
Syntax Description
Command Modes
Privileged EXEC
Command History
Examples
The following example resets the controller for the Fast Ethernet 0 interface on a Cisco 4500:
Router# clear interface fastethernet 0The 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 1/0The 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 1/0/0clear interface serial
To reset the statistical information specific to a serial interface, use the clear interface serial command in user EXEC mode.
clear interface serial dial-shelf/slot/t3-port:t1-num:chan-group
Syntax Description
Command Modes
EXEC
Command History
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 1/4/0:2:23Router#Related Commands
Clears the interface counters.
Displays statistics for all interfaces configured on the router or access server.
Displays information about a serial interface.
clear service-module serial
To reset an integrated CSU/DSU, use the clear service-module serial command in privileged EXEC configuration mode.
clear service-module serial number
Syntax Description
Command Modes
Privileged EXEC
Command History
Usage Guidelines
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
Examples
The following example resets the CSU/DSU on a router:
Router# clear service-module serial 0Router#Related Commands
Clears the interface counters.
Performs self-tests on an integrated CSU/DSU serial interface module, such as a 4-wire, 56/64-kbps CSU/DSU.
clock rate
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 clock rate command in interface configuration mode. To remove the clock rate if you change the interface from a DCE to a DTE device, use the no form of this command. Using the no form of this command on a DCE interface sets the clock rate to the hardware-dependent default value.
clock rate bps
no clock rate
Syntax Description
Defaults
No clock rate is configured.
Command Modes
Interface configuration
Command History
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:
•
•
•
•
•
•
•
•
Examples
The following example sets the clock rate on the first serial interface to 64,000 bits per second:
Router(config)# interface serial 0Router(config-if)# clock rate 64000The 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 5/0Router(config-if)# clock rate 1234567%clock rate rounded to nearest value that your hardware can support.%Use Exec Command 'more system: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 terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# interface serial 5/0Router(config-if)# clock rate 1234567%clock rate 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)# exitRouter(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-configBuilding configuration......!interface Serial5/0no ip addressclock rate 1151526!...clock source
To configure the clock source of a DS1 link, enter the clock source command in interface configuration, controller configuration, or ATM interface configuration mode. To restore the default line setting, use the no form of this command.
clock source {line | internal | loop-timed}
no clock source
Syntax Description
Defaults
The default value is line.
Command Modes
Interface configuration
Controller configuration for the Cisco MC3810 multiservice access concentrator.
ATM interface configuration for the Cisco 2600 and 3600 series routers.
Command History
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 0/2Router(config-if)# clock source internalRelated Commands
clock source (AS5200)
To select the clock source for the time-division multiplexing (TDM) bus in a Cisco AS5200 access server, use the clock source command in interface configuration mode. To restore the clock source to its default setting, use the no form of this command.
clock source {line {primary | secondary} | internal}
no clock source line {primary | secondary}
Syntax Description
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
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 0Router(config-controller)# clock source line primaryRouter(config)# controller t1 1Router(config-controller)# clock source line secondaryclock source (controller)
To set the T1-line clock source for the Multichannel Interface Processor (MIP) in the Cisco 7200 series and Cisco 7500 series, the NPM in the Cisco 4000 series, a T3 interface, or a PA-T3 serial port adapter, use the clock source command in controller configuration mode. To restore the clock source to its default setting, use the no form of this command.
clock source {line {primary | secondary} | internal}
no clock source
Syntax Description
Defaults
The default primary TDM clock source is from the T0 controller.
The default secondary TDM clock source is from the T1 controller.
The default clock for the interface's transmitted data is from a clock recovered from the line's receive data stream from the PA-T3 serial port adapter.
Command Modes
Controller configuration
Command History
10.3
This command was introduced.
11.1 CA
This command was modified to include the T3 serial port adapter and PA-T3 serial port adapter.
Usage Guidelines
This command applies to a Cisco 4000, Cisco 7000 series, Cisco 7200 series, or Cisco 7500 series router. A T3 interface on a PA-T3 serial port adapter can clock its transmitted data either from 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, 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 0AS5200(config-if)# clock source line primaryAS5200(config-if)# exitAS5200(config)# controller t1 1AS5200(config-if)# clock source line secondaryThe following example specifies the T3 interface to clock its transmitted data from its internal clock:
Router(config)# interface serial 1/0Router(config-if)# clock source internalRelated Commands
Selects the frame type for the T1 or E1 data line.
Selects the linecode type for T1 or E1 line.
clock source (CT3IP)
To specify where the clock source is obtained for use by the Channelized T3 Interface Processor (CT3IP) in Cisco 7500 series routers, use the clock source command in controller configuration mode. To restore the default clock source, use the no form of this command.
clock source {internal | line | loop-timed}
no clock source
Syntax Description
Defaults
The internal clock source is used.
Command Modes
Controller configuration
Command History
Usage Guidelines
If you do not specify the clock source command, the default internal clock source is used by the CT3IP.
You can also set the clock source for each T1 channel by using the t1 clock source controller configuration command.
Note
Examples
The following example sets the clock source for the CT3IP to line:
Router(config)# controller t3 9/0/0Router(config-if)# clock source lineRelated Commands
clock source (interface)
To control the clock from which a G.703-E1 interface, an E1-G.703/G.704 serial port adapter, or a PA-E3 serial port adapter clocks its transmitted data, use the clock source command in interface configuration mode. To restore the default clock source, use the no form of this command.
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
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
Usage Guidelines
Cisco 4000, 7000, 7200, and 7500 Series
A G.703-E1 interface, E1-G.703/G.704 serial port adapter, or a PA-E3 serial port adapter can clock its transmitted data from either its internal clock or from a clock recovered from the line's receive data stream.
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 0/1Router(config-if)# clock source internalCisco 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 0AS5200(config-if)# clock source line primaryAS5200(config-if)# exitAS5200(config)# controller t1 1AS5200(config-if)# clock source line secondaryclock source (MC3810)
To specify the clock source of a DS1 link on the Cisco MC3810 multiservice access concentrator, use the clock source command in controller configuration mode. To restore the clock source to its default setting, use the no form of this command.
clock source {line | internal | loop-timed}
no clock source
Syntax Description
Defaults
Line (when the MFT is installed)
Internal (when the DVM is installed)Command Modes
Controller configuration
Command History
Usage Guidelines
This command applies to Voice-over-Frame Relay, Voice-over-ATM, and Voice-over-HDLC on the Cisco MC3810.
Note
Examples
The following example configures the clock source for the MFT to internal, and the clock source for the DVM line on a Cisco MC3810 multiservice access concentrator:
Router(config)# controller T1 0Router(config-controller)# clock source internalRouter(config)# controller T1 1Router(config-controller)# clock source linecmt connect
To start the processes that perform the connection management (CMT) function and allow the ring on one fiber to be started, use the cmt connect command in EXEC mode.
cmt connect [fddi [port | slot/port] [phy-a | phy-b]]
Syntax Description
Command Modes
EXEC
Command History
Usage Guidelines
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.
The cmt connect command is not needed in the normal operation of FDDI; this command is used mainly in interoperability tests.
This command does not have a no form.
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 connectThe following command starts both fibers on FDDI interface unit 0:
Router# cmt connect fddi 0The following command on the Cisco 7200 series or Cisco 7500 series starts both fibers on FDDI interface unit 0:
Router# cmt connect fddi 1/0The following command starts only Physical Sublayer A on FDDI interface unit 0:
Router# cmt connect fddi 0 phy-aThe following command on Cisco 7500 series routers starts only Physical Sublayer A on FDDI interface unit 0:
Router# cmt connect fddi 1/0 phy-acmt disconnect
To stop the processes that perform the connection management (CMT) function and allow the ring on one fiber to be stopped, use the cmt disconnect command in EXEC mode.
cmt disconnect [fddi [port | slot/port] [phy-a | phy-b]]
Syntax Description
Command Modes
EXEC
Command History
Usage Guidelines
In normal operation, the FDDI interface is operational once the interface is connected and configured, and is turned off using the shutdown command in interface configuration mode. 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.
This command does not have a no form.
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 disconnectThe following command stops both fibers on FDDI interface unit 0:
Router# cmt disconnect fddi 0The following command on the Cisco 7200 series or Cisco 7500 series stops both fibers on FDDI interface unit 0:
Router# cmt disconnect fddi 1/0The 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-aThe following command on the Cisco 7500 series stops only Physical Sublayer A on 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-acompress
To configure software compression for Link Access Procedure, Balanced (LAPB), PPP, and High-Level Data Link Control (HDLC) encapsulations, use the compress command in interface configuration mode. 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.
compress {predictor | stac}
no compress {predictor | stac}
Cisco VIP2 Cards
compress {predictor | stac [distributed | software]}
Cisco 7200 Series and Cisco 7500 Series
compress {predictor | stac [csa slot | software]}
PPP Encapsulation
compress [predictor | stac | mppc [ignore-pfc]]
Syntax Description
Defaults
Compression is disabled.
Command Modes
Interface configuration
Command History
10.3
This command was introduced.
11.3 P
The following keywords were added:
•
•
•
11.3 T
The following keywords were added:
•
•
Note
Usage Guidelines
Compression reduces the size of frames via lossless data compression. You can configure point-to-point software compression for all LAPB, PPP, and HDLC encapsulations. HDLC encapsulations supports the Stacker compression algorithm. PPP and LAPB encapsulations support both predictor and Stacker compression algorithms.
MPPC Compression
The compress command using the mppc and ignore-pfc options support compression between Cisco routers and access servers and Microsoft clients, such as Windows 95 and Windows NT. MPPC implements an LZ based compression algorithm that uses a compression dictionary to compress PPP packets. The ignore-pfc keyword instructs the router to ignore the protocol field compression flag negotiated by LCP. For example, the uncompressed standard protocol field value for IP is 0x0021 and 0x21 when compression is enabled. When the ignore-pfc option is enabled, the router will continue to use the uncompressed value (0x0021). Using the ignore-pfc option is helpful for some asynchronous driver devices which use an uncompressed protocol field (0x0021), even though the pfc is negotiated between peers. If protocol rejects are displayed when the debug ppp negotiation command is enabled, setting the ignore-pfc option may remedy the problem.
Point-to-Point Compression
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. The compression algorithm used is a predictor algorithm (the RAND compression algorithm), which uses a compression dictionary to predict what the next character in the frame will be.
End-point devices must be configured to use the same compression method (predictor, Stacker or MPPC).
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
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.
Table 6 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 7 shows a summary of the compressed serial line rates for software compression. The maximums shown in Table 7 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 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
Note
Examples
The following example enables hardware compression and PPP encapsulation on serial interface 3/1/0.
Router(config)# interface serial 3/1/0Router(config-if)# encapsulate pppRouter(config-if)# compress stacThe following example enables predictor compression on serial interface 0 for a LAPB link:
Router(config)# interface serial 0Router(config-if)# encapsulation lapbRouter(config-if)# compress predictorRouter(config-if)# mtu 1509Router(config-if)# lapb n1 12072The 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 0Router(config-if)# encapsulation lapbRouter(config-if)# compress predictorThe following example configures BRI interface 0 to perform MPPC:
Router(config)# interface BRI0Router(config-if)# ip unnumbered ethernet0Router(config-if)# encapsulation pppRouter(config-if)# isdn spid1 5551234Router(config-if)# dialer map ip 172.21.71.74 5551234Router(config-if)# dialer-group 1Router(config-if)# compress mppcThe following example configures asynchronous interface 1 to implement MPPC and ignore the protocol field compression flag negotiated by LCP:
Router(config)# interface async1Router(config-if)# ip unnumbered ethernet0Router(config-if)# encapsulation pppRouter(config-if)# async default routingRouter(config-if)# async dynamic routingRouter(config-if)# async mode interactiveRouter(config-if)# peer default ip address 172.21.71.74Router(config-if)# compress mppc ignore-pfcRelated Commands
compress mppc
To configure compression using the Microsoft PPC (MPPC) compression algorithm on your data compression Advanced Interface Module (AIM) for the Cisco 2600 series router, use the compress mppc command in interface configuration mode. The MPPC compression algorithm is used to exchange compressed information with a Microsoft NT remote access server. To disable compression, use the no form of this command.
compress mppc
no compress
Syntax Description
This command has no keywords or arguments.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
When configuring PPP on a serial interface, you can use hardware compression on the data compression AIM daughtercard for MPPC if one is installed; otherwise you can use software compression.
Examples
The following example shows how to configure the data compression AIM daughtercard for MPPC:
Router(config-if)# encapsulate pppRouter(config-if)# compress mppcRelated Commands
compress predictor
The compress predictor command is replaced by the compress command. See the description of the compress command in this chapter for more information.
compress stac caim
To specify the exact hardware compression resource preferred, enter the compress stac caim command in interface configuration mode. To disable compression, use the no form of this command.
compress stac caim element-number
no compress stac caim element-number
Syntax Description
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
Specifying the compress stac command with no options causes the router to use the fastest available compression method.
Hardware Compression
If the router contains a data compression Advanced Interface Module (CAIM), compression is performed in the CAIM hardware.
Using hardware compression in the AIM frees the main processor of the router for other tasks. You can also configure the router to use the Compression Port Module to perform compression by using the distributed option, or to use the router's main processor by using the software option. If the Compression Port Module compression is performed in the main processor of the router.
Software Compression
If the CAIM is not available, compression is performed in the main processor of the router.
When compression is performed in software installed in the router's main memory, it might significantly affect system performance. It is recommended that you disable compression in the main processor if the router CPU load exceeds 40 percent. To display the CPU load, use the show process cpu command in EXEC mode.
Examples
The following example specifies that hardware compression should be activated for CAIM element 0:
Router(config-if)# encapsulation pppRouter(config-if)# compress stac caim 0Router(config)# Ctrl-ZRouter# show compressRouter(config)# interface serial 3/1Router(config-if)# encapsulation pppRouter(config-if)# compress stacRelated Commands
controller
To configure a T1 or E1 controller and enter controller configuration mode, use the controller command in global configuration mode.
Cisco 7200 Series and Cisco 7500 Series Routers
controller {t1 | e1} slot/port
Cisco AS5200 and AS5300 Access Servers and Cisco 4000 Series Routers
controller {t1 | e1} number
Cisco AS5800 Access Servers
controller t1 dial-shelf/slot/t3-port:t1-num
Cisco AS5800 Access Servers with Channelized T3 Interface Processor (CT3IP)
controller t3 dial-shelf/slot/t3-port
Cisco 7500 Series Cisco 7500 Series Routers with Channelized T3 Interface Processor (CT3IP)
controller t3 slot/port-adapter/port
Syntax Description
Defaults
No T1, E1, or T3 controller is configured.
Command Modes
Global configuration
Command History
Usage Guidelines
T1 or E1 Fractional Data Lines
This command is used in configurations where the router or access server is intended to communicate with a T1 or E1 fractional data line. Additional parameters for the T1 or E1 line must be configured for the controller before the T1 or E1 circuits can be configured by means of the interface global configuration command.
CT3IP Channel Interface Cards
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.
Examples
Cisco 7500 Series Router as a T1 Controller
The following example configures the MIP in slot 4, port 0 of a Cisco 7500 series router as a T1 controller:
controller t1 4/0Cisco 4000 Series Router
The following example configures NIM 0 of a Cisco 4000 series router as a T1 controller:
controller t1 0Cisco AS5800 Access Server with Dial Shelf
The following example configures the T1 controller in shelf 1, slot 0, port 0:
Router(config)# controller t1 1/0/0Router(config-controller)#Cisco 7500 Series
The following example configures the CT3IP in slot 3:
Router(config)# controller t3 3/0/0Cisco AS5800 Access Server
The following example shows the status of the T1 controllers connected to the Cisco AS5800:
Router# show controller T1T1 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 Violations0 Slip Secs, 0 Fr Loss Secs, 7 Line Err Secs, 0 Degraded Mins0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 7 Unavail SecsTotal 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 SecsT1 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 Violations0 Slip Secs, 7 Fr Loss Secs, 7 Line Err Secs, 0 Degraded Mins0 Errored Secs, 0 Bursty Err Secs, 0 Severely Err Secs, 7 Unavail SecsTotal 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 SecsRouter#Table 8 describes the fields shown in the display.
Related Commands
Defines the time slots that belong to each T1 or E1 circuit.
Resets the T1 or E1 controller.
clock source line
Sets the E1 line clock source for the Cisco AS5200.
controller t3
Configures the Channelized T3 Interface Processor.
framing
Selects the frame type for the T1 or E1 data line.
linecode
Selects the linecode type for T1 or E1 line.
show controllers e1
Displays information about the E1 links supported by the NPM
(Cisco 4000) or MIP (Cisco 7500 series).show controllers t1 call-counters
Displays the total number of calls and call durations on 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).
controller t3
To configure the Channelized T3 Interface Processor (CT3IP) in Cisco 7500 series routers or the CT3 feature board in Cisco AS5800 access servers, use the controller t3 command in global configuration mode. To delete the defined controller, use the no form of this command.
Cisco 7500 Series
controller t3 slot/port-adapter/port
no controller t3 slot/port-adapter/port
Cisco AS5800 Access Server
controller t3 dial-shelf/slot/t3-port
no controller t3 dial-shelf/slot/t3-port
Syntax Description
Defaults
Cisco 7500 Series
No T3 controller is configured.
Cisco AS5800 Access Server
No default behavior or values.
Command Modes
Global configuration
Command History
11.3
This command was introduced.
12.0(3)T
This command was implemented on the Cisco AS5800 access server.
Usage Guidelines
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
Examples
Cisco 7500 Series
The following example configures the CT3IP in slot 3:
Router(config)# controller t3 3/0/0Cisco AS5800 Access Server
The following example configures the T3 controller in shelf 3, slot 0, port 0 and T1 time slot 1:
Router(config)# controller t3 3/0/0Related Commands
copy flash lex
To download an executable image from Flash memory on the core router to a LAN Extender, use the copy flash lex command in privileged EXEC mode.
copy flash lex number
Syntax Description
Command Modes
Privileged EXEC
Command History
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.
This command does not have a no form.
Examples
The following example copies the executable image namexx to LAN Extender interface 0:
Router# copy flash lex 0Name of file to copy? namexxAddress of remote host [255.255.255.255] <cr>writing namexx !!!!!!!!!!!!!!!!!!!!!!!!!copy completeRelated Commands
copy tftp lex
To download an executable image from a TFTP server to the LAN Extender, use the copy tftp lex command privileged EXEC mode.
copy tftp lex number
Syntax Description
Command Modes
Privileged EXEC
Command History
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.
This command does not have a not form.
Examples
The following example copies the file namexx from the TFTP server:
Router# copy tftp lex 0Address or name of remote host (255.255.255.255]? 10.108.1.111Name of file to copy? namexxOK to overwrite software version 1.0 with 1.1 ?[confirm] YLoading namexx from 10.108.13.111!!!!!!!!!!!!!!!!!!!!!!!!![OK - 127825/131072 bytes]Successful download to LAN Extendercrc
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 command in interface configuration mode. To set the CRC length to 16 bits, use the no form of this command.
crc size
no crc
Syntax Description
Defaults
16 bits
Command Modes
Interface configuration
Command History
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 Switched Multimegabit Data Service (SMDS) networks and LANs.
Examples
The following example enables the 32-bit CRC on serial interface 3/0:
Router(config)# interface serial 3/0Router(config-if)# crc 32crc4
To enable generation of CRC4 (per ITU Recommendation G.704 and G.703) to improve data integrity, use the crc4 command in interface configuration mode. To disable this feature, use the no form of this command.
crc4
no crc4
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
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 applies to a Cisco 4000 router and to Cisco 7200 series, Cisco 7000 series, and Cisco 7500 series routers. This command is supported on the Fast Serial Interface Processor (FSIP) and the E1-G.703/G.704 serial port adapter.
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 High-Level Data Link Control (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 0/0Router(config-if)# crc 32Router(config-if)# crc4crc bits 5
To enable generation of CRC5 (per ITU Recommendation G.704 and G.703) to improve data integrity, use the crc bits 5 command in interface configuration mode. To disable this feature, use the no form of this command.
crc bits 5
no crc bits 5
Syntax Description
This command has no arguments or keywords.
Defaults
The default is no CRC5 checking.
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is available for the JT2 6.3-MHz serial port adapter (PA-2JT2) on the 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 the 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 High-Level Data Link Control (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 0/0Router(config-if)# crc 32Router(config-if)# crc bits 5Related Commands
cut-through
To configure the interfaces on the PA-12E/2FE port adapter to use cut-through switching technology between interfaces within the same bridge group, use the cut-through command in interface configuration mode. To return each interface to store-and-forward switching, use the no form of this command.
cut-through [receive | transmit]
no cut-through
Syntax Description
receive
(Optional) Selects cut-through switching technology on received data.
transmit
(Optional) Selects cut-through switching technology on transmitted data.
Defaults
Store-and-forward switching technology (that is, no cut-through)
Command Modes
Interface configuration
Command History
Usage Guidelines
Cut-through mode allows switched packets to be transmitted after 64 bytes are received. The transmission of the packets can start before the end of the packet arrives. This reduces the time spent in the switch, but allows packets to be transmitted with bad cyclical redundancy check (CRCs), because the transmission is initiated before the CRC is received or checked. Store-and-forward mode waits for the entire packet to be received before that packet is forwarded, but will check the CRC before starting transmission.
The PA-12E/2FE port adapter offloads Layer 2 switching from the host CPU by using store-and-forward or cut-through switching technology between interfaces within the same virtual LAN (VLAN) on the PA-12E/2FE port adapter. The PA-12E/2FE port adapter supports up to four VLANs (bridge groups).
Examples
The following example configures interface 3/0 for cut-through switching:
Router(config)# interface fastethernet 3/0Router(config-if)# bridge-group 10Router(config-if)# cut-throughRouter(config-if)# no shutdownRouter(config-if)# exitRouter(config)#Related Commands
