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Cisco IOS Interface Command Reference, Release 12.2 T
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Interface Commands (alarm-interface through cut-through
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Interface commands (dce-terminal-timing enable through interface content-engine)
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Interface Commands (interface fastethernet through logging event)
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Interface commands (main-fiber port through serial restart-delay)
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Interface Commands (service single-slot-reload-enable through show interfaces hssi)
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Interface Commands (show interfaces loopback through show pc hog-info)
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Interface Commands (show pas caim through srp tx-traffic-rate)
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Interface Commands (storm-control through yellow)
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Hardware Management Commands (au-3 through clock source (T3/E3 controller))
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Hardware Management Commands (controller through service-module t1 timeslots)
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Hardware Mangement Commands (show controllers cbus through show controllers token)
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Hardware Management Commands (show controllers vg-anylan through t1 yellow)
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Dial Shelf Management Commands (clear dsip tracing through show redundancy)
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Index
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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:
General interface
"Interface Configuration Overview" chapter in the Cisco IOS Interface Configuration Guide
LAN interface
"Configuring LAN Interfaces" chapter in the
Cisco IOS Interface Configuration GuideSerial interface
"Configuring Serial Interfaces" chapter in the Cisco IOS Interface Configuration Guide
Logical interface
"Configuring Logical Interfaces" chapter in the Cisco IOS Interface Configuration Guide
Cisco Mainframe Channel Connection (CMCC) adapters
"Configuring Cisco Mainframe Channel Connection Adapters" chapter in the Cisco IOS Bridging and IBM Networking Configuration Guide
Dialer interface and virtual-access interface
Cisco IOS Dial Technologies Configuration Guide and Cisco IOS Dial Technologies Command Reference
ISDN PRI interface
Cisco IOS Dial Technologies Configuration Guide and Cisco IOS Dial Technologies Command Reference
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.
The LAN Extension feature will no longer be offered after Cisco IOS Release 12.2(15)T. LAN Extension documentation in the Cisco IOS Interface Command Reference, Release 12.2 can be accessed at:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/finter_r/index.htm
The following LAN Extension commands have been removed from documentation in Cisco IOS Software Release 12.2(15)T and will not appear in future releases of the Cisco IOS software documentation set:
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clear controller lex
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alarm-interface
To enter alarm interface mode and configure the alarm interface controller (AIC), use the alarm-interface command in global configuration mode. To leave alarm interface mode, use the exit command.
alarm-interface slot-number
Syntax Description
Defaults
No default behavior or values
Command Modes
Global configuration
Command History
12.2(2)XG
This command was introduced for the Cisco 2600 series and the Cisco 3600 series.
12.2(8)T
This command was integrated into Cisco IOS Release 12.2(8)T.
Examples
The following examples show how the alarm-interface command is used in conjunction with the ip address and the reset commands:
Router(config)# alarm-interface 5Router(config-aic)# ip address 10.2.130.105A change in the AIC IP configuration might not take effect until the next time the card is started. Use the reset command to restart the card, as in the following example:
Router(config-aic)# resetAlarm Interface Card in slot 5 restartedRouter(config-aic)# endRelated Commands
ip address
Sets a primary or secondary IP address for an interface.
reset
Resets the AIC CPU.
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 in interface 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)# exitRelated 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
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; the bandwidth values can be displayed using the show interface EXEC command.
Command Modes
Interface configuration
Command History
Usage Guidelines
Bandwidth Information
The bandwidth command sets an informational parameter to communicate only the current bandwidth to the higher-level protocols; you cannot adjust the actual bandwidth of an interface with this command.
Note
Changing Bandwidth
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.
Examples
The following example sets the full bandwidth for DS3 transmissions:
Router(config)# interface serial 0Router(config-if)# bandwidth 44736Related Commands
show interfaces
Displays statistics for all interfaces configured on the router.
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; the 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 that you choose depends on the nature of the link outages that you expect to see in your network and how long you expect those outages to last.
If data links in your network 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. If outages in your network 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 (EtherChannel)
To assign and configure a Fast Ethernet interface to an EtherChannel group, use the channel-group command in interface configuration mode. To remove the channel-group configuration from the interface, use the no form of this command.
Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series Routers
channel-group port-channel-number mode on
no channel-group
Catalyst Switches
channel-group port-channel-number mode {on | auto [non-silent] | desirable [non-silent]}
no channel-group
Syntax Description
Defaults
No channel groups are assigned.
Command Modes
Interface configuration
Command History
Usage Guidelines
IP Address for the Physical Interface
You do not have to disable the IP address that is assigned to a physical interface that is part of a channel group, but Cisco highly recommends doing so.
Layer-2 and Layer-3 Port Channels
You can create both Layer 2 and Layer 3 port channels by entering the interface port-channel command or, when the channel-group gets its first physical interface assignment. The port channels are not created at run time, nor are they created dynamically.
You do not have to create a port-channel interface before assigning a physical interface to a channel group. A port-channel interface is automatically created when the channel group gets its first physical interface, if it is not already created.
Propagation of Configuration and Attribute Changes
Any configuration or attribute changes you make to the port-channel interface are propagated to all interfaces within the same channel group as the port channel. (for example, configuration changes are also propagated to the physical interfaces that are not part of the port-channel, but are part of the channel group.)
The on Keyword
When you use the on keyword, a usable EtherChannel exists only when a port group in "on" mode is connected to another port group in the "on" mode.
Cisco 2600 Series, Cisco 3600 Series, and Cisco 3700 Series Routers
You do not have to create a port-channel interface before assigning a physical interface to a channel group. A port-channel interface is created automatically when the channel group gets its first physical interface, if it is not already created.
Catalyst Switches
The number of valid values for port-channel-number depends on the software release. For software releases prior to Cisco IOS Release 12.1(3a)E3, valid values are from 1 to 256; for Cisco IOS Release 12.1(3a)E3, 12.1(3a)E4, and 12.1(4)E1, valid values are from 1 to 64. Cisco IOS Release 12.1 E and later releases support a maximum of 64 values ranging from 1 to 256.
Caution
Examples
This example shows how to add EtherChannel interface 1/0 to the EtherChannel group specified by port-channel 1:
Router(config-if)# channel-group 1 mode on
Related Commands
interface port-channel
Accesses or creates the IDB port-channel.
show interfaces port-channel
Displays statistics for all interfaces configured.
channel-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 counters
To clear the interface counters, use the clear counters command in user EXEC mode.
clear counters [type number]
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 1.
number
(Optional) Specifies the interface counter displayed with the show interfaces command.
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
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 1 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 2.
number
Port, connector, or interface card number.
name-tag
(Optional for use with the RLM feature) Logic name to identify the server configuration so that multiple server configurations can be entered.
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 that support channelized T1, specifies the channel number 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 type and number arguments are specified to clear only a specific interface type (serial, Ethernet, Token Ring, and so on). Table 2 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 Cisco 4700 series
clear interface fastethernet number
Cisco 7200 and Cisco 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
Cisco 4500
The following example resets the controller for Fast Ethernet interface 0 on a Cisco 4500:
Router# clear interface fastethernet 0Cisco 7200 and Cisco 7500
The following example resets the controller for the Fast Ethernet interface located in slot 1 port 0 on a Cisco 7200 series router or Cisco 7500 series router:
Router# clear interface fastethernet 1/0Cisco 7500
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 1/0/0Related Commands
Clears the interface counters.
Displays statistics for all interfaces configured on the router or access server.
Displays information about a serial interface.
clear 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 fastethernet interface.
clear ipc statistics
To clear all interprocess communication (IPC) statistics, use the clear ipc statistics command in privileged EXEC mode.
clear ipc statistics
Syntax Description
This command has no arguments or keywords.
Command Modes
Privileged EXEC
Command History
Usage Guidelines
The clear ipc statistics command clears all the IPC statistics and is useful for troubleshooting issues with IPC services.
Examples
The following example shows how to clear all of the statistics used by IPC services. A show ipc status command is issued first to display the current IPC counters for a local IPC server. The clear ipc statistics command is then entered to clear and reset the counters. A final show ipc status command is issued to show that all the counters, except those counters that show the packets sent since the clearing, are reset to zero.
Router# show ipc statusIPC System StatusTime last IPC stat cleared : neverThis processor is the IPC master server.Do not drop output of IPC frames for test purposes.1000 IPC Message Headers Cached.Rx Side Tx SideTotal Frames 189 140Total from Local Ports 189 70Total Protocol Control Frames 70 44Total Frames Dropped 0 0Service UsageTotal via Unreliable Connection-Less Service 145 0Total via Unreliable Sequenced Connection-Less Svc 0 0Total via Reliable Connection-Oriented Service 44 70IPC Protocol Version 0Total Acknowledgements 70 44Total Negative Acknowledgements 0 0Device DriversTotal via Local Driver 0 0Total via Platform Driver 0 70Total Frames Dropped by Platform Drivers 0 0Reliable Tx StatisticsRe-Transmission 0Re-Tx Timeout 0Rx Errors Tx ErrorsUnsupp IPC Proto Version 0 Tx Session Error 0Corrupt Frame 0 Tx Seat Error 0Duplicate Frame 0 Destination Unreachable 0Out-of-Sequence Frame 0 Tx Test Drop 0Dest Port does Not Exist 0 Tx Driver Failed 0Rx IPC Msg Alloc Failed 0 Ctrl Frm Alloc Failed 0Unable to Deliver Msg 0Buffer Errors Misc ErrorsIPC Msg Alloc 0 IPC Open Port 0Emer IPC Msg Alloc 0 No HWQ 0IPC Frame PakType Alloc 0 Hardware Error 0IPC Frame MemD Alloc 0Tx Driver ErrorsNo Transport 0MTU Failure 0Dest does not Exist 0Router# clear ipc statisticsRouter# show ipc statusIPC System StatusTime last IPC stat cleared : 00:00:03This processor is the IPC master server.Do not drop output of IPC frames for test purposes.1000 IPC Message Headers Cached.Rx Side Tx SideTotal Frames 26 0Total from Local Ports 26 0Total Protocol Control Frames 0 0Total Frames Dropped 0 0Service UsageTotal via Unreliable Connection-Less Service 26 0Total via Unreliable Sequenced Connection-Less Svc 0 0Total via Reliable Connection-Oriented Service 0 0IPC Protocol Version 0Total Acknowledgements 0 0Total Negative Acknowledgements 0 0Device DriversTotal via Local Driver 0 0Total via Platform Driver 0 0Total Frames Dropped by Platform Drivers 0 0Reliable Tx StatisticsRe-Transmission 0Re-Tx Timeout 0Rx Errors Tx ErrorsUnsupp IPC Proto Version 0 Tx Session Error 0Corrupt Frame 0 Tx Seat Error 0Duplicate Frame 0 Destination Unreachable 0Out-of-Sequence Frame 0 Tx Test Drop 0Dest Port does Not Exist 0 Tx Driver Failed 0Rx IPC Msg Alloc Failed 0 Ctrl Frm Alloc Failed 0Unable to Deliver Msg 0Buffer Errors Misc ErrorsIPC Msg Alloc 0 IPC Open Port 0Emer IPC Msg Alloc 0 No HWQ 0IPC Frame PakType Alloc 0 Hardware Error 0IPC Frame MemD Alloc 0Tx Driver ErrorsNo Transport 0MTU Failure 0Dest does not Exist 0Related Commands
cmt 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]}
[no] compress {predictor | stac [distributed | software]}
Cisco 7200 Series and Cisco 7500 Series
compress {predictor | stac [csa slot | software]}
[no] compress {predictor | stac [csa slot | software]}
PPP Encapsulation
compress [predictor | stac | mppc [ignore-pfc]]
[no] 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
Point-to-Point Compression
Compression reduces the size of frames through lossless data compression. You can configure point-to-point software compression for all LAPB, PPP, and HDLC encapsulations. 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 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 standard protocol field value for IP is 0x0021 when compression is disabled 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 that 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.
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 3 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 that you are using and which compression algorithm you specify. Table 4 shows a summary of the compressed serial line rates for software compression. The maximums shown in Table 4 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 compression or one 256-kbps line. These maximums also assume that 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 daughter card 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 stac caim
To specify the hardware compression, use 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
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 by the software installed in the router's main memory, system performance might be affected significantly. 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-ZRelated Commands
crc
To set the length of the cyclic redundancy check (CRC) on a Fast Serial Interface Processor (FSIP) or HSSI Interface Processor (HIP) of the Cisco 7500 series routers or on a 4-port serial adapter of the Cisco 7200 series routers, use the crc 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
