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Cisco IOS Interface and Hardware Component Command Reference, Release 12.3
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Introduction
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Interface and Hardware Component Commands: A through C
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Interface and Hardware Component Commands: D through H
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Interface and Hardware Component Commands: I through L
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Interface and Hardware Component Commands: M through R
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Interface and Hardware Component Commands: scramble through show aps
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Interface and Hardware Component Commands: show compress through show hub
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Interface and Hardware Component Commands: show interfaces through syscon source-interface
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Interface and Hardware Component Commands: T through Z
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Table Of Contents
loopback (PA-MC-8TE1+ port adapter)
ignore-dcd
To configure the serial interface to monitor the Data Set Ready (DSR) signal instead of the Data Carrier Detect (DCD) signal as the line up/down indicator, use the ignore-dcd command in interface configuration mode. To restore the default, use the no form of this command.
ignore-dcd
no ignore-dcd
Syntax Description
This command has no arguments or keywords.
Defaults
The serial interface, operating in DTE mode, monitors the DCD signal as the line up/down indicator.
Command Modes
Interface configuration
Command History
Usage Guidelines
This command applies to Quad Serial NIM interfaces on the Cisco 4000 series routers and Hitachi-based serial interfaces on the Cisco 2500 and Cisco 3000 series routers.
Serial Interfaces in DTE Mode
When the serial interface is operating in DTE mode, it monitors the DCD signal as the line up/down indicator. By default, the attached DCE device sends the DCD signal. When the DTE interface detects the DCD signal, it changes the state of the interface to up.
SDLC Multidrop Environments
In some configurations, such as an Synchronous Data Link Control (SDLC) multidrop environment, the DCE device sends the DSR signal instead of the DCD signal, which prevents the interface from coming up. Use this command to tell the interface to monitor the DSR signal instead of the DCD signal as the line up/down indicator.
Examples
The following example shows how to configure serial interface 0 to monitor the DSR signal as the line up/down indicator:
Router(config)# interface serial 0Router(config-if)# ignore-dcdignore-hw local-loopback
To disable the monitoring of the (local-loopback) LL pin when in DCE mode, use the ingnore-hw local-loopback command in interface configuration mode. To enable the monitoring of the LL pin, use the no form of this command.
ignore-hw local-loopback
no ignore-hw local-loopback
Syntax Description
This command has no arguments or keywords.
Defaults
Enabled
Command Modes
Interface configuration
Command History
Usage Guidelines
Use this command if your system is experiencing spurious modem interrupts that momentarily cause the interface to enter loopback mode. The end result of this behavior is the loss of Synchronous Data Link Control (SDLC) Logical Link Control (SDLLC) sessions.
Note
This command works only with the low-speed serial interfaces.
Examples
The following example shows how to disable the monitoring of the LL pin when in DCE mode:
Router(config)# interface serial 2Router(config-if)# ignore-hw local-loopbackinterface
To configure an interface type and enter interface configuration mode, use the interface command in global configuration mode.
Standard Syntax
interface type number [name-tag]
Cisco 7200 Series and Cisco 7500 Series with a Packet over SONET Interface Processor
interface type slot/port
Cisco 7200 VXR Router used as a Router Shelf in an AS5800 Universal Access Server
interface type router-shelf/slot/port
Cisco 7500 Series with Channelized T1 or E1
interface serial slot/port:channel-group
Cisco 7500 Series with Ports on VIP Cards
interface type slot/port-adapter/port
Content Engine Network Module
interface content-engine slot/unit
To configure a subinterface, use this form of the interface global configuration command.
Cisco 7200 Series
interface type slot/port.subinterface-number [multipoint | point-to-point]
Cisco 7500 Series
interface type slot/port-adapter.subinterface-number [multipoint | point-to-point]
Cisco 7500 Series with Ports on VIP Cards
interface type slot/port-adapter/port.subinterface-number [multipoint | point-to-point]
Syntax Description
type
Type of interface to be configured. See Table 9.
number
Port, connector, or interface card number. On Cisco 4700 series routers, specifies the network interface module (NIM) or network processor module (NPM) number. The numbers are assigned at the factory at the time of installation or when added to a system, and can be displayed with the show interfaces command.
name-tag
(Optional) Specifies the logic name to identify the server configuration so that multiple entries of server configuration can be entered.
This optional argument is for use with the Redundant Link Manager (RLM) feature.
slot
Slot number. Refer to the appropriate hardware manual for slot and port information.
/port
Port number. Refer to the appropriate hardware manual for slot and port information.
router-shelf
Router shelf number in a Cisco AS5800 universal access server. Refer to the appropriate hardware manual for slot and port information.
:channel-group
Channel group number. Cisco 7500 series routers specify the channel group number in the range of 0 to 4 defined with the channel-group controller configuration command.
/port-adapter
Port adapter number. Refer to the appropriate hardware manual for information about port adapter compatibility.
/unit
Number of the daughter card on the network module. For content engine (CE) network modules, always use 0.
.subinterface-number
Subinterface number in the range 1 to 4,294,967,293. The number that precedes the period (.) must match the number to which this subinterface belongs.
multipoint | point-to-point
(Optional) Specifies a multipoint or point-to-point subinterface. There is no default.
Defaults
No interface types are configured.
Command Modes
Global configuration
Note
Command History
Usage Guidelines
Subinterfaces can be configured to support partially meshed Frame Relay networks. Refer to the "Configuring Serial Interfaces" chapter in the Cisco IOS Interface and Hardware Component Configuration Guide.
This command does not have a no form.
Using the group-async Keyword
Using the group-async keyword, you create a single asynchronous interface to which other interfaces are associated as members using the group-range command. This one-to-many configuration allows you to configure all associated member interfaces by entering one command on the group master interface, rather than entering this command on each individual interface. You can create multiple group masters on a device; however, each member interface can be associated only with one group.
Using the port-channel Keyword
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. You can configure the port-channel interface as you would do to any Fast Ethernet interface.
After you create a port-channel interface, you assign Fast Ethernet interfaces (up to four) to it. For information on how to assign a Fast Ethernet interface to a port-channel interface, refer to the channel-group interface configuration command.
Caution
Caution
As you work with the port-channel keyword, consider the following points:
•
•
Using the vg-anylan Keyword
The 100VG-AnyLAN port adapter provides a single interface port that is compatible with and specified by IEEE 802.12. The 100VG-AnyLAN port adapter provides 100 Mbps over Category 3 or Category 5 unshielded twisted-pair (UTP) cable with RJ-45 terminators, and supports IEEE 802.3 Ethernet packets.
You configure the 100VG-AnyLAN port adapter as you would any Ethernet or Fast Ethernet interface. The 100VG-AnyLAN port adapter can be monitored with the IEEE 802.12 Interface MIB.
Examples
The following example shows how to configure serial interface 0 with PPP encapsulation:
Router(config)# interface serial 0Router(config-if)# encapsulation pppThe following example shows how to enable loopback mode and assigns an IP network address and network mask to the interface. The loopback interface established here will always appear to be up:
Router(config)# interface loopback 0Router(config-if)# ip address 10.108.1.1 255.255.255.0The following example shows how to configure Ethernet port 4 on the Ethernet Interface Processor (EIP) in slot 2 on the Cisco 7500 series router:
Router(config)# interface ethernet 2/4The following example shows how to configure the Token Ring interface processor in slot 1 on port 0 of a Cisco 7500 series routers:
Router(config)# interface tokenring 1/0The following example configures an interface for a content engine network module in slot 1:
Router(config)# interface content-engine 1/0The following example shows how to configure Fast Ethernet interface 0 for standard ARPA encapsulation (the default setting) on a Cisco 4700 series router:
Router(config)# interface fastethernet 0The following example shows how to configure Gigabit Ethernet interface for slot 0, port 0:
Router(config)# interface gigabitethernet 0/0The following example shows how to define asynchronous group master interface 0:
Router(config)# interface group-async 0The following example shows how to create a port-channel interface with a channel group number of 1 and adds two Fast Ethernet interfaces to port-channel 1:
Router(config)# interface port-channel 1Router(config-if)# ip address 10.1.1.10 255.255.255.0Router(config-if)# exitRouter(config)# interface fastethernet 1/0/0Router(config-if)# channel-group 1Router(config-if)# exitRouter(config)# interface fastethernet 4/0/0Router(config-if)# channel-group 1The following example shows how to create a port-channel interface with a channel group number of 1 and adds two Gigabit Ethernet interfaces to port-channel 1:
Router(config)# int port-channel 1Router(config-if)# ip address 10.1.1.10 255.255.255.0Router(config-if)# exitRouter(config)# int gigabitethernet 0/0Router(config-if)# channel-group 1Router(config-if)# exitRouter(config)# int gigabitethernet 0/1Router(config-if)# channel-group 1The following example shows how to specify the single Packet OC-3 interface on port 0 of the POS OC-3 port adapter in slot 2:
Router(config)# interface pos 2/0/0The following example shows how to specify the 100VG-AnyLAN port adapter in the first port adapter in slot 1:
Router(config)# interface vg-anylan 1/0/0The following example shows how to configure a partially meshed Frame Relay network. In this example, subinterface serial 0.1 is configured as a multipoint subinterface with three associated Frame Relay permanent virtual connections (PVCs), and subinterface serial 0.2 is configured as a point-to-point subinterface.
Router(config)# interface serial 0Router(config-if)# encapsulation frame-relayRouter(config-if)# exitRouter(config)# interface serial 0/0.1 multipointRouter(config-if)# ip address 10.108.10.1 255.255.255.0Router(config-if)# frame-relay interface-dlci 42 broadcastRouter(config-if)# frame-relay interface-dlci 53 broadcastRouter(config-if)# exitRouter(config)# interface serial 0/0.2 point-to-pointRouter(config-if)# ip address 10.108.11.1 255.255.0Router(config-if)# frame-relay interface-dlci 59 broadcastThe following example shows how to configure circuit 0 of a T1 link for Point-to-Point Protocol (PPP) encapsulation:
Router(config)# controller t1 4/1Router(config-controller)# circuit 0 1Router(config-controller)# exitRouter(config)# interface serial 4/1:0Router(config-if)# ip address 10.108.13.1 255.255.255.0Router(config-if)# encapsulation pppRelated Commands
interface content-engine
The interface content-engine command is now documented as the content-engine keyword of the interface command. For more information, see the interface command.
interface fastethernet
The interface fastethernet command is now documented as the fastethernet keyword of the interface command. For more information, see the interface command.
interface gigabitethernet
The interface gigabitethernet command is now documented as the gigabitethernet keyword of the interface command. For more information, see the interface command.
interface group-async
The interface group-async command is now documented as the group-async keyword of the interface command. For more information, see the interface command.
interface port-channel
The interface port-channel command is now documented as the port-channel keyword of the interface command. For more information, see the interface command.
interface pos
The interface pos command is now documented as the pos keyword of the interface command. For more information, see the interface command.
interface range
To execute commands on multiple subinterfaces at the same time, use the interface range command in global configuration command mode.
interface range {fastethernet interfacenumber - interfacenumber | gigabitethernet interfacenumber - interfacenumber | loopback number | tunnel number | port-channel number | vlan number | macro word}
Syntax Description
Defaults
No default behavior or values
Command Modes
Global configuration
Command History
Usage Guidelines
Configuration Changes
All configuration changes made to a range of subinterfaces are saved to NVRAM, but the range itself does not get savedto NVRAM. Use the define interface-range command to create and save a range.
You can enter the range in two ways:
•
•
You can specify either the interfaces or the name of a range macro. A range must consist of the same interface type, and the interfaces within a range cannot span slots.
You cannot specify both an interface range and a macro keyword in the same command. After creating a macro, the CLI does not allow you to enter additional ranges. Likewise, if you have already entered an interface range, the CLI does not allow you to enter a macro.
The spaces around the dash in the interface range command syntax are required. For example, using a Catlyst 6500 router, the command interface range fastethernet 1 - 6 is valid; the command interface range fastethernet 1-6 is not valid.
VLAN Ranges
When you define a Catalyst Vlans, valid values are from 1 to 4094. The last VLAN number cannot exceed 4094.
You cannot use the interface range command to create switch virtual interfaces (SVIs). You must create SVIs with individual interface VLAN commands. You can use the interface range command on existing VLAN SVIs. To display VLAN SVIs, enter the show running-config command. VLANs not displayed cannot be used in the interface range command.
The commands entered under the interface range command are applied to all existing VLAN SVIs.
Examples
The following example shows how to use the interface range command to configure a fastethernet range:
Router(config)# interface range fastethernet5/1 - 4Router(config-if-range)#
The following example shows how to set a vlan:
Cisco-65K(config)#interface range vlan 123Cisco-65K(config-if-range)#The following example configures the Fast Ethernet subinterfaces within the range from 5/1.1 to 5/1.4 and applies the following VLAN IDs to those subinterfaces:
Fast Ethernet5/1.1 = VLAN ID 301 (vlan-id)Fast Ethernet5/1.2 = VLAN ID 302 (vlan-id = 301 + 2 - 1 = 302)Fast Ethernet5/1.3 = VLAN ID 303 (vlan-id = 301 + 3 - 1 = 303)Fast Ethernet5/1.4 = VLAN ID 304 (vlan-id = 301 + 4 - 1 = 304)Router(config)# interface range fastethernet5/1 - 4Router(config-if)# encapsulation dot1q 301Router(config-if)# no shutdownRouter(config-if)#*Oct 6 08:24:35: %LINK-3-UPDOWN: Interface FastEthernet5/1.1, changed state to up*Oct 6 08:24:35: %LINK-3-UPDOWN: Interface FastEthernet5/1.2, changed state to up*Oct 6 08:24:35: %LINK-3-UPDOWN: Interface FastEthernet5/1.3, changed state to up*Oct 6 08:24:35: %LINK-3-UPDOWN: Interface FastEthernet5/1.4, changed state to up*Oct 6 08:24:36: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet5/1.1, changed state to up*Oct 6 08:24:36: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet5/1.2, changed state to up*Oct 6 08:24:36: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet5/1.3, changed state to up*Oct 6 08:24:36: %LINEPROTO-5-UPDOWN: Line protocol on Interface FastEthernet5/1.4, changed state to upThe following example shows how to execute a range macro:
Router(config)# interface range macro macro1The following exampe shows how to set a gigabitethernet range:
Router(config)# interface range gigabitethernet1/1 - 6Router(config-if-range)#
The following example shows how to use the loopback interface:
Router(config)# interface range loopback 34567Router(config-if-range)#
The following example shows how to use the tunnel interface:
Router(config)# interface range tunnel 55555Router(config-if-range)#
The following example shows how to use the port-channel interface:
Router(config)# interface range port-channel 343Router(config-if-range)#
Related Commands
interface vg-anylan
The interface vg-anylan command is now documented as the vg-anylan keyword of the interface command. For more information, see the interface command.
international bit
To set the E3 international bit in the G.751 frame used by the PA-E3 port adapter, use the international bit command in interface configuration mode. To return to the default international bit, use the no form of this command.
international bit {0 | 1} {0 | 1}
no international bit
Syntax Description
0
Sets either of the two required E3 international bits in the G.751 frame to 0. This is the default.
1
Sets either of the two required E3 international bits in the G.751 frame to 1.
Defaults
The default value for each bit is 0.
Command Modes
Interface configuration
Command History
Usage Guidelines
The international bit command sets bits 6 and 8, respectively, of set II in the E3 frame.
To verify the international bit configured on the interface, use the show controllers serial EXEC command.
Examples
The following example sets the international bit to 1 1 on the PA-E3 port adapter in slot 1, port adapter slot 0, interface 0:
Router(config)# interface serial 1/0/0Router(config-if)# international bit 1 1Related Commands
invert data
To invert the data stream, use the invert data command in interface configuration mode. This command applies only to the Cisco 7000 series routers with the RSP7000 and RSP7000CI, Cisco 7200 series routers, and Cisco 7500 series routers. To disable inverting the data stream, use the no form of this command.
invert data
no invert data
Syntax Description
This command has no arguments or keywords.
Defaults
Data is not inverted.
Command Modes
Interface configuration
Command History
11.1 CA
This command was introduced.
11.2 P
This command was integrated into Cisco IOS Release 11.2 P.
Usage Guidelines
T1 Line Without B8ZS Encoding
If the interface on the PA-8T and PA-4T+ synchronous serial port adapters and the PA-T3 and PA-2T3 synchronous serial port adapters is used to drive a dedicated T1 line that does not have B8ZS encoding (a method to avoid 15 zeros), the data stream must be inverted (both transmitting and receiving data) either in the connecting CSU/DSU or in the interface.
Inverting is a method of avoiding excessive zeroes that is superseded by the use of B8ZS encryption. This option could be needed for use with legacy equipment that supports this option. By inverting the High-Level Data Link Control (HDLC) data stream, the HDLC zero insertion algorithm becomes a ones insertion algorithm that satisfies the T1 requirements. Be careful not to invert data both on the interface and on the CSU/DSU because two data inversions will cancel each other out.
AMI Line Coding
If the interface on the CT3IP uses alternate mark inversion (AMI) line coding, you must also invert the data on the T1 channel. For more information, see the t1 linecode controller configuration command.
Examples
The following example inverts data on serial interface 3/1/0:
Router(config)# interface serial 3/1/0Router(config-if)# invert dataRelated Commands
t1 linecode
Specifies the type of linecoding used by the T1 channels on the CT3IP in Cisco 7500 series routers.
invert rxclock
To invert the phase of the receive (RX) clock signal on the universal I/O (UIO) serial interface that does not use the T1/E1 interface, use the invert rxclock command in interface configuration mode. To disable the phase inversion, use the no form of this command.
invert rxclock
no invert rxclock
Syntax Description
This command has no arguments or keywords.
Defaults
The receive clock signal is not inverted.
Command Modes
Interface configuration
Command History
Usage Guidelines
When a delay occurs between a signal being sent and the signal being received it can indicate that the receive clock signal is not appropriate for the interface rate. This command allows the receive clock signal to be inverted to attempt to correct the delay.
Examples
The following example inverts the receive clock signal on serial interface 1:
Router(config)# interface serial 1Router(config-if)# invert rxclockinvert txclock
To invert the transmit (TX) clock signal, use the invert txclock command in interface configuration mode. To return the TX clock signal to its initial state, use the no form of this command.
invert txclock
no invert txclock
Syntax Description
This command has no arguments or keywords.
Defaults
The transmit clock signal is not inverted.
Command Modes
Interface configuration
Command History
10.0
This command was introduced.
11.3
The invert-transmit-clock command was replaced by the invert txclock command.
Usage Guidelines
Delays between the serial clock transmit external (SCTE) clock and data transmission indicate that the TX clock signal might not be appropriate for the interface rate and length of cable being used. Different ends of the wire can have variances that differ slightly. The invert txclock command compensates for these variances. This command replaces the invert-transmit-clock command.
Systems that use long cables or cables that are not transmitting the TxC signal (transmit echoed clock line, also known as TXCE or SCTE clock) can experience high error rates when operating at the higher transmission speeds. For example, if a PA-8T synchronous serial port adapter is reporting a high number of error packets, a phase shift might be the problem. Inverting the clock might correct this shift.
When a PA-8T or PA-4T+ port adapter interface is DTE, the invert txclock command inverts the TxC signal it received from the remote DCE. When the PA-8T or PA-4T+ port adapter interface is DCE, this command changes the signal back to its original phase.
Examples
The following example inverts the TX clock signal on serial interface 3/0:
Router(config)# interface serial 3/0Router(config-if)# invert txclockkeepalive
To enable keepalive packets and to specify the number of times that the Cisco IOS software tries to send keepalive packets without a response before bringing down the interface or before bringing the tunnel protocol down for a specific interface, use the keepalive command in interface configuration mode. When the keepalive function is enabled, a keepalive packet is sent at the specified time interval to keep the interface active. To turn off keepalive packets entirely, use the no form of this command.
keepalive [period [retries]]
no keepalive [period [retries]]
Syntax Description
Defaults
period: 10 seconds
retries: 5
If you enter only the keepalive command with no arguments, defaults for both arguments are used.
If you enter only the keepalive command and the timeout parameter, the default number of retries (5) is used.
If you enter the no keepalive command, keepalive packets are disabled on the interface.Command Modes
Interface configuration
Command History
Usage Guidelines
Keepalive Time Interval
You can configure the keepalive time interval, which is the frequency at which the Cisco IOS software sends messages to itself (Ethernet and Token Ring) or to the other end (serial and tunnel), to ensure that a network interface is alive. The interval is adjustable in 1-second increments down to 1 second. An interface is declared down after three update intervals have passed without receiving a keepalive packet unless the retry value is set higher.
Note
Setting the keepalive timer to a low value is very useful for rapidly detecting Ethernet interface failures (transceiver cable disconnecting, cable not terminated, and so on).
Line Failure
A typical serial line failure involves losing Carrier Detect (CD) signal. Because this sort of failure is typically noticed within a few milliseconds, adjusting the keepalive timer for quicker routing recovery is generally not useful.
Keepalive Packets with Tunnel Interfaces
GRE keepalive packets may be sent from both sides of a tunnel, or from just one side. If they are sent from both sides, the period and retry parameters can be different at each side of the link. If you configure keepalives on only one side of the tunnel, the tunnel interface on the sending side might perceive the tunnel interface on the receiving side to be down because the sending interface is not receiving keepalives. From the receiving side of the tunnel, the link appears normal because no keepalives were enabled on the second side of the link.
Dropped Packets
Keepalive packets are treated as ordinary packets, so it is possible that they will be dropped. To reduce the chance that dropped keepalive packets will cause the tunnel interface to be taken down, increase the number of retries.
Note
delay the smaller keepalive packets long enough to cause the line protocol to go down. You may
need to experiment to determine the best values to use for the timeout and the number of
retry attempts.GRE Tunnels with IPSec
When using GRE with IPSec, the keepalives are encrypted like any other traffic. As with user data packets, if the IKE and IPSec security associations are not already active on the GRE tunnel, the first GRE keepalive packet will trigger IKE/IPSec initialization.
Examples
The following example shows how to set the keepalive interval to 3 seconds:
Router(config)# interface ethernet 0Router(config-if)# keepalive 3The following example shows how to set the keepalive interval to 3 seconds and the retry value to 7:
Router(config)# interface tunnel 1Router(config-if)# keepalive 3 7lbo
To set a cable length longer than 655 feet for a DS-1 link, use the lbo command in interface configuration mode on the interface for a T1 link. To delete the lbo value, use the no form of this command.
lbo {long {gain26 | gain36} {-15db | -22.5db | -7.5db | 0db} | short {133 | 266 | 399 | 533 | 655}}
no lbo
Syntax Description
Defaults
gain26 and 0db
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is supported on T1 links only.
Each T1 port can operate in long-haul or short-haul mode. In long haul mode, the user must specify the gain and the line build out. In short-haul mode, the user must specify the cable length in feet.
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
On Cisco 7100 or Cisco 7200 series routers, the following example specifies a pulse gain of 36 decibels and a decibel pulse rate of -7.5 decibels:
Router(config)# interface atm 1/2Router(config-if)# lbo long gain36 -7.5dblinecode
To select the line-code type for T1 or E1 lines, use the linecode command in controller configuration mode.
linecode {ami | b8zs | hdb3}
Syntax Description
Defaults
AMI is the default for T1 lines.
High-density bipolar 3 is the default for E1 lines.Command Modes
Controller configuration
Command History
Usage Guidelines
Use this command in configurations in which the router or access server must communicate with T1 fractional data lines. The T1 service provider determines which line-code type, either ami or b8zs, is required for your T1 circuit. Likewise, the E1 service provider determines which line-code type, either ami or hdb3, is required for your E1 circuit.
This command does not have a no form.
Examples
The following example specifies B8ZS as the line-code type:
Router(config-controller)# linecode b8zsline-termination
To set the line termination on an E1 controller, use the line-termination command in controller configuration mode. To return to the default line termination, use the no form of this command.
line-termination {75-ohm | 120-ohm}
no line-termination
Syntax Description
75-ohm
Specifies 75-ohm unbalanced termination.
120-ohm
Specifies 120-ohm balanced termination. This is the default.
Defaults
120-ohms
Command Modes
Controller configuration
Command History
Usage Guidelines
This command applies only to E1 controllers. To determine the line termination setting for the controller, use the show controllers e1 command.
Examples
In the following example, the line termination is set to 75 ohms for the E1 port located in shelf 6, slot 0, port 0:
Router# configure terminalRouter(config)# controller e1 6/0/0Router(config-controller)# line-termination 75-ohmRouter(config-controller)# endRelated Commands
show controllers e1
Displays information about the E1 links supported by the NPM (Cisco 4000) or MIP (Cisco 7500 series).
link-test
To reenable the link-test function on a port on an Ethernet hub of a Cisco 2505 or Cisco 2507 router, use the link-test command in hub configuration mode. To disable this function, use the no form of this command.
link-test
no link-test
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. Disable this feature if a 10Base-T twisted-pair device at the other end of the hub does not implement the link test function.
Examples
The following example disables the link test function on hub 0, ports 1 through 3:
Router(config)# hub ethernet 0 1 3Router(config-hub)# no link-testRelated Commands
hub
Enables and configures a port on an Ethernet hub of a Cisco 2505 or Cisco 2507 router.
local-lnm
To enable Lanoptics Hub Networking Management of a PCbus Token Ring interface, use the local-lnm command in interface configuration mode. To disable Lanoptics Hub Networking Management, use the no form of this command.
local-lnm
no local-lnm
Syntax Description
This command has no arguments or keywords.
Defaults
Management is not enabled.
Command Modes
Interface configuration
Command History
Usage Guidelines
The Token Ring interface on the AccessPro PC card can be managed by a remote LAN manager over the PCbus interface. At present, the Lanoptics Hub Networking Management software running on an IBM compatible PC is supported.
Examples
The following example enables Lanoptics Hub Networking Management:
Router(config-if)# local-lnmlogging event
To enable notification of interface, subinterface, and Frame Relay data link connection identifier (DLCI) data link status changes, use the logging event command in interface configuration mode. To disable notification, use the no form of this command.
logging event {dlci-status-change | link-status | subif-link-status [ignore-bulk]}
no logging event {dlci-status-change | link-status | subif-link-status [ignore-bulk]}
Syntax Description
Defaults
For system images, notification of interface, subinterface, and Frame Relay DLCI data link status changes is enabled by default.
For boot images, notification of Frame Relay subinterface and DLCI data link status changes is disabled by default. Notification of interface data link status changes is enabled by default.
Command Modes
Interface configuration
Command History
Examples
The following example shows how to enable notification of subinterface link status changes:
Router(config-if)# logging event subif-link-statusThe following are examples of Frame Relay DLCI and subinterface status change notification messages filtered by the logging event command:
00:16:22: %FR-5-DLCICHANGE: Inteface Serial3/0/0:1 - DLCI 105 state changed to INACTIVE00:16:22: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial3/0/0:1.5, changed state to downlogging event atm pvc state
To enable notification of ATM permanent virtual circuit (PVC) state changes, use the logging event atm pvc state command in interface configuration mode. To disable notification, use the no form of this command.
logging event atm pvc state
no logging event atm pvc state
Syntax Description
This command has no arguments or keywords.
Command Default
None
Command Modes
Interface configuration
Command History
Usage Guidelines
For monitoring purposes, this command can be used to log the state changes for all PVCs associated with an ATM interface.
Examples
The following example shows how to enable notification of ATM PVC state changes:
Router(config-if)# logging event atm pvc stateRelated Commands
loopback (E3 controller)
To loop an entire E3 line toward the line and back toward the router, use the loopback command in controller configuration mode. To remove the loop, use the no form of this command.
loopback {local | network {line | payload}}
no loopback
Syntax Description
Defaults
local
Command Modes
Controller configuration
Command History
Usage Guidelines
Use this command for troubleshooting purposes. To verify that a loopback is configured on the interface, use the show controllers e3 EXEC command. Note that line loopback is available only in C-bit parity mode.
Examples
The following example shows how to configure the controller located in slot 1, port 0 for a local loopback:
Router(config)# controller e3 1/0Router(config-controller)# loopback localRelated Commands
loopback (interface)
To diagnose equipment malfunctions between the interface and device, use the loopback command in interface configuration mode. To disable the test, use the no form of this command.
loopback
no loopback
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
Loopback on HSSI Cards
On High-Speed Serial Interface (HSSI) cards, the loopback function configures a two-way internal and external loop on the HSA applique of the specific interface.
Loopback on MCI and SCI Serial Interface Cards
On MCI and SCI serial interface cards, the loopback functions when a CSU/DSU or equivalent device is attached to the router or access server. The loopback command loops the packets through the CSU/DSU to configure a CSU loop, when the device supports this feature.
Loopback on MCI and MEC Ethernet Cards
On the MCI and MEC Ethernet cards, the interface receives back every packet it sends when the loopback command is enabled. Loopback operation has the additional effect of disconnecting network server functionality from the network.
Loopback on CSC-FCI FDDI Cards
On the CSC-FCI FDDI card, the interface receives back every packet it sends when the loopback command is enabled. Loopback operation has the additional effect of disconnecting network server functionality from the network.
Loopback on Token Ring Interface Cards
On all Token Ring interface cards (except the 4-megabit CSC-R card), the interface receives back every packet it sends when the loopback command is enabled. Loopback operation has the additional effect of disconnecting network server functionality from the network.
Active Loopback Interfaces
To show interfaces currently in loopback operation, use the show interfaces loopback EXEC command.
Note
Examples
The following example configures the loopback test on Ethernet interface 4:
Router(config)# interface ethernet 4Router(config-if)# loopbackRelated Commands
down-when-looped
Configures an interface to inform the system it is down when loopback is detected.
show interfaces loopback
Displays information about the loopback interface.
loopback (J1 controller )
To set the loopback method for testing the J1 interface, use the loopback command in controller configuration mode. To turn off loopback, use the no form of this command. This command should be used for testing purposes only.
loopback {local | line | isolation}
no loopback {local | line | isolation}
Syntax Description
local
Places the interface into local loopback mode.
line
Places the interface into external loopback mode at the line level.
isolation
Places the interface into both local and line loopback mode.
Defaults
No loopback is configured.
Command Modes
Controller configuration
Command History
Examples
The following example establishes a loopback of the incoming J1 signal on controller J1 3/0:
Router(config)# controller j1 3/0Router(config-controller)# loopback lineloopback (PA-MC-8TE1+ port adapter)
To enable loopback testing of data for the PA-MC-8TE1+ port adapter, use the loopback command in interface configuration mode. To disable loopback testing, use the no form of this command.
loopback [internal | line]
no loopback [internal | line]
Syntax Description
Defaults
Loopback mode is not enabled.
Command Modes
Interface configuration
Command History
Examples
In the following example, a loopback is set for the PA-MC-8TE1+ port adapter in slot 2:
Router(config)# interface 2/0Router(config-if)# loopback lineloopback (T1 interface)
To loop individual T1 channels on the CT3IP in Cisco 7000 series routers that have the RSP7000 and RSP7000CI and in Cisco 7500 series routers, use the loopback command in interface configuration mode. To remove the loopback, use the no form of this command.
loopback [local | network {line | payload} | remote {line {fdl {ansi | bellcore} | inband} | payload [fdl] [ansi]}]
no loopback
Syntax Description
Defaults
No loopback is configured.
Command Modes
Interface configuration
Command History
Usage Guidelines
Use this command for troubleshooting purposes.
To better diagnose T1 provisioning problems, you can place the remote CSU or remote SmartJack into loopback. The loopback remote line fdl interface configuration command allows you to place either the CSU or the SmartJack into loopback:
•
•
When both are configured, transmission of loss of frame (LOF) indication (yellow alarm) takes priority over transmission of some facilities data link (FDL) messages.
If the remote loopback appears not to be working, use the show controllers t3 command to determine if the given T1 is currently attempting to transmit a LOF indication (yellow alarm):
Router# show controllers t3 0/0/0:2T3 0/0/0 is up.CT3 H/W Version: 5, CT3 ROM Version: 1.2, CT3 F/W Version: 2.5.9Mx H/W version: 2, Mx ucode ver: 1.34T1 2 is down, speed: 1536 kbs, non-inverted datatimeslots: 1-24FDL per AT&T 54016 spec.Transmitter is sending LOF Indication.Receiver is getting AIS.If the transmitter is sending a LOF indication, as in the previous example, stop the transmission of the LOF indication (yellow alarm) with the no t1 yellow generation configuration command as shown in the following example:
Router(config)# controllers t3 0/0/0Router(config-controller)# no t1 2 yellow generationRouter(config-controller)# Ctrl-DTo verify that the transmission of the LOF indication (yellow alarm) has stopped, use the show controllers t3 command:
Router# show controllers t3 0/0/0:2T3 0/0/0 is up.CT3 H/W Version: 5, CT3 ROM Version: 1.2, CT3 F/W Version: 2.5.9Mx H/W version: 2, Mx ucode ver: 1.34T1 2 is down, speed: 1536 kbs, non-inverted datatimeslots: 1-24FDL per AT&T 54016 spec.Receiver is getting AIS.Framing is ESF, Line Code is B8ZS, Clock Source is Internal.Yellow Alarm Generation is disabledThen retry the remote loopback command. When diagnosis is complete, remember to reenable the LOF indication (yellow alarm).
You can also loopback all the T1 channels by using the loopback (CT3IP) interface configuration command.
Examples
The following example configures T1 channel 5 for a local loopback:
Router(config)# interface serial 3/0/0:5Router(config-if)# loopback localRelated Commands
loopback (T3 controller)
To loop the entire T3 (all 28 T1 channels) line on the T3 controller or on the CT3IP in Cisco 7500 series routers, use the loopback command in controller configuration mode. To remove the loop, use the no form of this command.
loopback {local | network {line | payload} | remote}
no loopback
Syntax Description
Defaults
No loops are configured on the T3 line.
Command Modes
Controller configuration
Command History
Usage Guidelines
Use this command for troubleshooting purposes. To verify that a loopback is configured on the interface, use the show controllers T3 EXEC command. Note that remote loopback is available only in C-bit parity mode.
You can also loopback each T1 channel by using the loopback interface configuration command for T1.
For more information, refer to the "Troubleshooting the T3 and T1 Channels" section in the "Configuring Serial Interfaces" chapter of the Cisco IOS Interface and Hardware Component Configuration Guide.
Examples
The following example configures the T3 or CT3IP for a local loopback:
Router(config)# controller t3 3/0/0Router(config-controller)# loopback localRelated Commands
loopback (T3/E3 interface)
To loop the serial interface on a PA-T3 or PA-E3 port adapter, use the loopback command in interface configuration mode. To remove the loopback, use the no form of this command.
PA-T3 Port Adapter
loopback {dte | local | network {line | payload} | remote}
no loopback
PA-E3 Port Adapter
loopback {dte | local | network {line | payload}}
no loopback
Syntax Description
Defaults
No loops are configured on the serial interface.
Command Modes
Interface configuration
Command History
Usage Guidelines
Use this command for troubleshooting purposes.
To verify that a loopback is configured on the interface, use the show interfaces serial or show interfaces loopback command.
Examples
The following example configures the serial interface located in slot 3/0/0 for a local loopback:
Router(config)# interface serial 3/0/0Router(config-if)# loopback localRelated Commands
loopback applique
To configure an internal loop on the High-Speed Serial Interface (HSSI) applique, use the loopback applique command in interface configuration mode. To remove the loop, use the no form of this command.
loopback applique
no loopback applique
Syntax Description
This command has no arguments or keywords.
Defaults
No loops are configured on the HSSI applique.
Command Modes
Interface configuration
Command History
Usage Guidelines
This command loops the packets within the applique to provide a way to test communication within the router or access server. It is useful for sending pings to yourself to check functionality of the applique.
To show a specific interface that is currently in loopback operation, use the show interfaces loopback EXEC command.
Examples
The following example configures the loopback test on the HSSI applique:
Router(config)# interface serial 1Router(config-if)# loopback appliqueRelated Commands
loopback dte
To loop packets back to the DTE from the CSU/DSU, when the device supports this function, use the loopback dte command in interface configuration mode. To remove the loop, use the no form of this command.
loopback dte
no loopback dte
Syntax Description
This command has no arguments or keywords.
Defaults
No loops are configured.
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is useful for testing the DTE-to-DCE cable.
This command is used to test the performance of the integrated CSU/DSU. Packets are looped from within the CSU/DSU back to the serial interface of the router. Send a test ping to see if the packets successfully looped back. To cancel the loopback test, use the no loopback dte command.
When using the 4-wire 56/64-kbps CSU/DSU module, an out-of-service signal is transmitted to the remote CSU/DSU.
To show a specific interface that is currently in loopback operation, use the show interfaces loopback EXEC command.
Examples
The following example configures the loopback test on the DTE interface:
Router(config)# interface serial 0Router(config-if)# loopback dteRelated Commands
loopback line
To loop packets completely through the CSU/DSU to configure the CSU loop, use the loopback line command in interface configuration mode. To remove the loop, use the no form of this command.
loopback line [payload]
no loopback line [payload]
Syntax Description
payload
(Optional) Configures a loopback point at the DSU and loops data back to the network on an integrated CSU/DSU.
Defaults
No loops are configured.
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is useful for testing the DCE device (CSU/DSU) itself. When the loopback line command is configured on the 2-wire 56-kbps CSU/DSU module or the 4-wire 56/64-kbps CSU/DSU modules, the network data loops back at the CSU and the router data loops back at the DSU. If the CSU/DSU is configured for switched mode, you must have an established connection to perform a payload-line loopback. To loop the received data through the minimum amount of CSU/DSU circuitry, issue the loopback line command.
When you issue the loopback line payload command on an integrated CSU/DSU module, the router cannot transmit data through the serial interface for the duration of the loopback. Choosing the DSU as a loopback point loops the received-network data through the maximum amount of CSU/DSU circuitry. Data is not looped back to the serial interface. An active connection is required when operating in switched mode for payload loopbacks.
If you enable the loopback line command on the fractional T1/T1 module, the CSU/DSU performs a full-bandwidth loopback through the CSU portion of the module and data transmission through the serial interface is interrupted for the duration of the loopback. No reframing or corrections of bipolar violation errors or cyclic redundancy check (CRC) errors are performed. When you configure the loopback line payload command on the FT1/T1 module, the CSU/DSU performs a loopback through the DSU portion of the module. The loopback line payload command reframes the data link, regenerates the signal, and corrects bipolar violations and Extended Super Frame CRC errors.
When performing a T1-line loopback with Extended Super Frame, communication over the facilities data link is interrupted, but performance statistics are still updated. To show interfaces currently in loopback operation, use the show service-module EXEC command.
To show interfaces that are currently in loopback operation on other routers, use the show interfaces loopback EXEC command.
Examples
The following example configures the loopback test on the DCE device:
Router(config)# interface serial 1Router(config-if)# loopback lineThe following example shows how to configure a payload loopback on a Cisco 2524 or Cisco 2525 router:
Router1(config-if)# loopback line payloadLoopback in progressRouter1(config-if)# no loopback lineThe following example shows the output on a Cisco 2524 or Cisco 2525 router when you loop a packet in switched mode without an active connection:
Router1(config-if)# service-module 56k network-type switchedRouter1(config-if)# loopback line payloadNeed active connection for this type of loopback% Service module configuration command failed: WRONG FORMAT.Related Commands
show interfaces loopback
Displays information about the loopback interface.
show service-module
Displays the performance report for an integrated CSU/DSU.
loopback remote (interface)
To loop packets through a CSU/DSU, over a DS3 link or a channelized T1 link, to the remote CSU/DSU and back, use the loopback remote command in interface configuration mode. To remove the loopback, use the no form of this command.
FT1/T1 CSU/DSU Modules
loopback remote {full | payload | smart-jack} [0in1 | 1in1 | 1in2 | 1in5 | 1in8 | 3in24 | qrw | user-pattern 24-bit-binary-value]
no loopback remote {full | payload | smart-jack}
2- and 4-Wire, 56/64-kbps CSU/DSU Modules
loopback remote [2047 | 511 | stress-pattern pattern-number]
no loopback remote
Syntax Description
Defaults
No remote loopback interface is configured.
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is used for testing the data communication channels along with or without remote CSU/DSU circuitry. The loopback is usually performed at the line port, rather than the DTE port, of the remote CSU/DSU.
For a multiport interface processor connected to a network via a channelized T1 link, the loopback remote interface configuration command applies if the remote interface is served by a DDS line (56 kbps or 64 kbps) and if the device at the remote end is a CSU/DSU. In addition, the CSU/DSU at the remote end must react to latched DDS CSU loopback codes. Destinations that are served by other types of lines or that have CSU/DSUs that do not react to latched DDS CSU codes cannot participate in an interface remote loopback. Latched DDS CSU loopback code requirements are described in AT&T specification TR-TSY-000476, "OTGR Network Maintenance Access and Testing."
For the integrated FT1/T1 CSU/DSU module, the loopback remote full command sends the loopup code to the remote CSU/DSU. The remote CSU/DSU performs a full-bandwidth loopback through the CSU portion of the module. The loopback remote payload command sends the loopup code on the configured time slots, while maintaining the D4-extended super frame. The remote CSU/DSU performs the equivalent of a loopback line payload request. The remote CSU/DSU loops back only those time slots that are configured on the remote end. This loopback reframes the data link, regenerates the signal, and corrects bipolar violations and extended super frame CRC errors. The loopback remote smart-jack command sends a loopup code to the remote smart jack. You cannot put the local smart jack into loopback.
Failure to loopup or initiate a remote loopback request could be caused by enabling the no service-module t1 remote-loopback command or having an alternate remote-loopback code configured on the remote end. When the loopback is terminated, the result of the pattern test is displayed.
For the 2- and 4-wire, 56/64-kbps CSU/DSU module, an active connection is required before a loopup can be initiated while in switched mode. When transmitting V.54 loopbacks, the loopback mode is initiated on the remote device using V.54 messages. Failure to loopup or initiate a remote loopback request could be caused by enabling the no service-module 56k remote-loopback command.
To display interfaces that are currently in loopback operation, use the show interfaces loopback EXEC command.
Examples
Example for Remote Loopback Test
The following example configures a remote loopback test:
Router(config)# interface serial 0 Router(config-if)# loopback remoteExample of Full-Bandwidth Line Loopback
The following example configures the remote device into full-bandwidth line loopback while specifying the qrw test pattern over the T1 CSU/DSU module on a Cisco 2524 or Cisco 2525 router:
Router(config)# interface serial 0Router(config-if)# loopback remote full qrwRouter(config-if)#%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0, changed state to down%LINK-3-UPDOWN: Interface Serial0, changed state to down%SERVICE_MODULE-5-LOOPUPREMOTE: Unit 0 - Remote unit placed in loopbackExample of Loopback Stress Pattern
The following example transmits a remote loopback stress pattern over the 4-wire, 56/64-kbps CSU/DSU module, which tests the stress clocking of the network:
Router(config-if)# loopback remote stress-pattern 1Router(config-if)#%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial1, changed state to down%LINK-3-UPDOWN: Interface Serial1, changed state to down%SERVICE_MODULE-5-LOOPUPREMOTE: Unit 1 - Remote unit placed in loopbackRelated Commands
