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Cisco IOS Interface Command Reference, Release 12.2
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About the Cisco IOS Software Documentation
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Using Cisco IOS Software
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Interface Commands - Introduction
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Interface Commands (aps-authenticate - cut-through)
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Interface Commands (dce-terminal-timing enable - interface)
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Interface Commands (interface fastethernet - loopback line)
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Interface Commands (loopback remote - service module t1 remote-loopback)
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Interface Commands (service-module t1 timeslots - show hub)
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Interface Commands (show interfaces - show interfaces vg-anylan)
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Interface Commands (show pas caim - tx-queue-limit)
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Dial Shelf Management Commands
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Online index for Cisco IOS Interface Comand Reference
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Feedback
Table Of Contents
half-duplex controlled-carrier
dce-terminal-timing enable
To prevent phase shifting of the data with respect to the clock when running the line at high speeds and long distances, use the dce-terminal-timing enable command in interface configuration mode. If serial clock transmit external (SCTE) terminal timing is not available from the DTE, use the no form of this command; the DCE will use its own clock instead of SCTE from the DTE.
dce-terminal-timing enable
no dce-terminal-timing enable
Syntax Description
This command has no arguments or keywords.
Defaults
DCE uses its own clock.
Command Modes
Interface configuration
Command History
Usage Guidelines
On the Cisco 4000 router, you can specify the serial Network Interface Module timing signal configuration. When the board is operating as a DCE and the DTE provides terminal timing (SCTE or TT), the dce-terminal-timing enable command causes the DCE to use SCTE from the DTE.
Examples
The following example prevents phase shifting of the data with respect to the clock:
Router(config)# interface serial 0Router(config-if)# dce-terminal-timing enabledefault (interface)
To reset the configuration of an interface back to its default values, use the default command in global configuration mode.
default interface-type interface-number
Syntax Description
Defaults
Existing interface configuration values are not reset.
Command Modes
Global configuration
Command History
Usage Guidelines
The default command is a general-purpose command that is not limited to interfaces; it resets defaults based on the command name that follows it. Use the default (interface) command when you need to remove any configuration for a specified interface and reset the interface to its default values.
Examples
The following example demonstrates how to reset serial interface 0 to its default values.
Router(config)# default serial 0Related Commands
delay (interface)
To set a delay value for an interface, use the delay command in interface configuration mode. To restore the default delay value, use the no form of this command.
delay tens-of-microseconds
no delay
Syntax Description
tens-of-microseconds
Integer that specifies the delay in tens of microseconds for an interface or network segment. To see the default delay, use the show interfaces command.
Defaults
Default delay values may be displayed with the show interfaces EXEC command.
Command Modes
Interface configuration
Command History
Examples
The following example sets a delay of 30,000-microsecond on serial interface 3:
Router(config)# interface serial 3Router(config-if)# delay 3000Related Commands
show interfaces
Displays the statistical information specific to a serial interface.
description (controller)
To add a description to an E1 or T1 controller or the Channelized T3 Interface Processor (CT3IP) in Cisco 7500 series routers, use the description command in controller configuration mode. To remove the description, use the no form of this command.
description string
no description
Syntax Description
string
Comment or a description (up to 80 characters) to help you remember what is attached to an interface.
Defaults
No description is added.
Command Modes
Controller configuration
Command History
10.3
This command was introduced.
11.3
This command was modified to include the CT3IP controller.
Usage Guidelines
The description command is meant solely as a comment to be put in the configuration to help you remember what certain controllers are used for. The description affects the CT3IP and Multichannel Interface Processor (MIP) interfaces only and appears in the output of the show controller e1, show controller t3, show controller t1, and more system:running-config EXEC commands.
Examples
The following example describes a 3174 controller:
Router(config)# controller t1Router(config-controller)# description 3174 Controller for test labRelated Commands
down-when-looped
To configure an interface to inform the system that it is down when loopback is detected, use the down-when-looped command in interface configuration mode.
down-when-looped
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
This command is valid for High-Level Data Link Control (HDLC) or PPP encapsulation on serial and High-Speed Serial Interface (HSSI) interfaces.
This command does not have a no form.
Backup Interfaces
When an interface has a backup interface configured, it is often desirable that the backup interface be enabled when the primary interface is either down or in loopback. By default, the backup is only enabled if the primary interface is down. By using the down-when-looped command, the backup interface will also be enabled if the primary interface is in loopback.
Testing an Interface with the Loopback Command
If testing an interface with the loopback command, or by placing the DCE into loopback, the down-when-looped command should not be configured; otherwise, packets will not be transmitted out the interface that is being tested.
Examples
The following example configures interface serial 0 for HDLC encapsulation. It is then configured to let the system know that it is down when in loopback mode.
Router(config)# interface serial0Router(config-if)# encapsulation hdlcRouter(config-if)# down-when-loopedRelated Commands
backup interface
Configures an interface as a secondary or dial backup interface.
Diagnoses equipment malfunctions between an interface and a device.
dsu bandwidth
To specify the maximum allowable bandwidth used by the PA-E3 and PA-T3 port adapters, use the dsu bandwidth command in interface configuration mode. To return to the default bandwidth, use the no form of this command.
dsu bandwidth kbps
no dsu bandwidth
Syntax Description
kbps
Maximum bandwidth in the range of 22 kbps to 44736 kbps. The default values are:
•
34010 kbps for PA-E3
•
Defaults
34010 kbps for PA-E3
44736 kbps for PA-T3
Command Modes
Interface configuration
Command History
Usage Guidelines
The local interface configuration must match the remote interface configuration. For example, if you reduce the maximum bandwidth to 16000 on the local port, you must also do the same on the remote port.
The dsu bandwidth command reduces the bandwidth by padding the E3 and T3 frame.
To verify the data service unit (DSU) bandwidth configured on the interface, use the show controllers serial EXEC command.
Examples
The following example sets the DSU bandwidth to 16000 kbps on interface 1/0/0:
Router(config)# interface serial 1/0/0Router(config-if)# dsu bandwidth 16000Related Commands
dsu mode
To specify the interoperability mode used by a PA-E3 or PA-T3 port adapters, use the dsu mode command in interface configuration mode. The dsu mode command enables and improves interoperability with other DSUs. To return to the default mode, use the no form of this command.
dsu mode {0 | 1 | 2}
no dsu mode
Syntax Description
Defaults
0
Command Modes
Interface configuration
Command History
Usage Guidelines
The local interface configuration must match the remote interface configuration. For example, if you define the data service unit (DSU) interoperability mode as 1 on the local port, you must also do the same on the remote port.
You must know what type of DSU is connected to the remote port to determine if it interoperates with a PA-E3 or a PA-T3 port adapter. Use mode 0 to connect two PA-E3 port adapters or to connect the PA-E3 port adapter to a Digital Link DSU (DL3100). Use mode 1 to connect a PA-E3 or a PA-T3 port adapter to a Kentrox DSU. Use mode 2 to connect a PA-T3 port adapter to a Larscom DSU. The dsu mode command enables and improves interoperability with other DSUs.
To verify the DSU mode configured on the interface, use the show controllers serial EXEC command.
Examples
The following example sets the DSU mode to 1 on interface 1/0/0:
Router(config)# interface serial 1/0/0Router(config-if)# dsu mode 1Related Commands
dte-invert-txc
On the Cisco 4000 series, you can specify the serial Network Processor Module timing signal configuration. When the board is operating as a DTE, use the dte-invert-txc command in interface configuration mode to invert the TXC clock signal received from the DCE. If the DCE accepts serial clock transmit external (SCTE) from the DTE, use the no form of this command.
dte-invert-txc
no dte-invert-txc
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
Use this command if the DCE cannot receive SCTE from the DTE, the data is running at high speeds, and the transmission line is long. The dte-invert-txc command prevents phase shifting of the data with respect to the clock.
On the Cisco 4000 series, you can specify the serial Network Processor Module timing signal configuration. When the board is operating as a DTE, the dte-invert-txc command inverts the TXC clock signal it gets from the DCE that the DTE uses to transmit data.
If the DCE accepts SCTE from the DTE, use no dte-invert-txc.
Examples
The following example inverts the TXC on serial interface 0:
Router(config)# interface serial 0Router(config-if)# dte-invert-txcduplex
To configure duplex operation on an interface, use the duplex command in interface configuration mode. To return the system to half-duplex mode, the system default, use the no form of this command.
duplex {full | half | auto}
no duplex
Syntax Description
Defaults
Half-duplex mode
Command Modes
Interface configuration
Command History
Usage Guidelines
To use the autonegotiation capability (that is, detect speed and duplex modes automatically), you must set both speed and duplex to auto.
Table 9 describes the access server's performance for different combinations of the duplex and speed modes. The specified duplex command configured with the specified speed command produces the resulting system action.
For the Cisco AS5300, the duplex {full | half | auto} command syntax replaces the following two earlier duplex commands:
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•
You will get the following error messages if you try to use these commands on a Cisco AS5300:
Router(config)# interface fastethernet 0Router(config-if)# full-duplexPlease use duplex command to configure duplex modeRouter(config-if)#Router(config-if)# half-duplexPlease use duplex command to configure duplex modeExamples
The following example shows the different duplex configuration options you can configure on a Cisco AS5300:
Router# configure terminalEnter configuration commands, one per line. End with CNTL/Z.Router(config)# interface fastethernet 0Router(config-if)# duplex ?auto Enable AUTO duplex configurationfull Force full duplex operationhalf Force half-duplex operationRelated Commands
dxi interface-dfa
To specify a map command for a point to point serial interface, use the Data Exchange Interface (dxi) command dxi interface-dfa in interface configuration mode. To deletct the map command, use the no form of this command.
dxi interface-dfa vpi-number vci[snap | mux]
no dxi interface-dfa vpi-number vci
Syntax Description
Defaults
No map command is specified.
Command Modes
Interface configuration
Defaults
No map definition is established.
Command Modes
Interface configuration
Command History
10.3
This command was introduced.
12.4
This command was integrated into Cisco IOS Release 12.4.
Examples
The following example shows how to specify a map command.
Router(config)# interface serial 1Router(config-if)# dxi interface-dfa 10Related Commands
dxi pvc
Configures multiprotocol or single protocol AMT-Data Exchange Interface (dxi) encapsulation.
e2-clockrate
To configure the serial interface 0 for E2 (8 MHZ full duplex) and to shut down the other three serial interfaces (1 to 3), use the e2-clockrate command in interface configuration mode. To disable the full duplex E2, use the no form of this command.
e2-clockrate
no e2-clockrate
Syntax Description
This command has no arguments or keywords.
Defaults
The interfaces are not affected.
Command Modes
Interface configuration
Command History
Usage Guidelines
The e2-clockrate privileged EXEC command is an interface configuration command and is seen only with interface serial0. When this command is used, serial interface 0 supports speeds up to E2 (8 MHz full duplex) and the other three serial interfaces (1 to 3) are put in "shutdown" state. Also, running this command displays the following warning message:
Serial interface 0 is configured to support E2 rates and serial ports "1-3" are moved to shutdown state.Examples
The following example shows sample display output for the e2-clockrate EXEC command.
Router(config-if)# e2-clockrateInterface Serial 0 is configured to support clockrates up to E2 (8Mbps)Interfaces serial 1-3 will not be operationalRelated Commands
Configures the clock rate for the hardware connections on serial interfaces such as NIMs and interface processors to an acceptable bit rate.
early-token-release
To enable early token release on Token Ring interfaces, use the early-token-release command in interface configuration mode. To disable this feature, use the no form of this command.
early-token-release
no early-token-release
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
Early token release is a method whereby the Token Ring interfaces can release the token back onto the ring immediately after transmitting, rather than waiting for the frame to return. This feature helps increase the total bandwidth of the Token Ring.
The Token Ring Interface Processor (TRIP) on the Cisco 7500 series routers and the Token Ring adapters on the Cisco 7200 series routers all support early token release.
Examples
The following example enables the use of early token release on Token Ring interface 1:
Router(config)# interface tokenring 1Router(config-if)# early-token-releaseOn the Cisco 7500 series, to enable the use of early token release on your Token Ring interface processor in slot 4 on port 1, issue the following configuration commands:
Router(config)# interface tokenring 4/1Router(config-if)# early-token-releaseencapsulation
To set the encapsulation method used by the interface, use the encapsulation command in interface configuration mode. To remove the encapsulation use the no form of this command.
encapsulation encapsulation-type
no encapsulation encapsulation-type
Syntax Description
Defaults
The default depends on the type of interface. For example, synchronous serial interfaces default to HDLC and asynchronous interfaces default to SLIP.
Command Modes
Interface configuration
Command History
Usage Guidelines
To use SLIP or PPP, the router or access server must be configured with an IP routing protocol or with the ip host-routing command. This configuration is done automatically if you are using old-style slip address commands. However, you must configure it manually if you configure SLIP or PPP via the interface async command.
On lines configured for interactive use, encapsulation is selected by the user when they establish a connection with the slip or ppp EXEC command.
IP Control Protocol (IPCP) is the part of PPP that brings up and configures IP links. After devices at both ends of a connection communicate and bring up PPP, they bring up the control protocol for each network protocol that they intend to run over the PPP link such as IP or IPX. If you have problems passing IP packets and the show interface command shows that line is up, use the negotiations command to see if and where the negotiations are failing. You might have different versions of software running, or different versions of PPP, in which case you might need to upgrade your software or turn off PPP option negotiations. All IPCP options as listed in RFC 1332, "PPP Internet Protocol Control Protocol (IPCP)," are supported on asynchronous lines. Only Option 2, TCP/IP header compression, is supported on synchronous interfaces.
PPP echo requests are used as keepalive packets to detect line failure. The no keepalive command can be used to disable echo requests. For more information about the no keepalive command, refer to the chapter "IP Services Commands" in the Cisco IOS IP Command Reference, Volume 1 of 3: Addressing and Services and the chapter "Configuring IP Services" in the Cisco IOS IP Configuration Guide.
To use SLIP or PPP, the Cisco IOS software must be configured with an IP routing protocol or with the ip host-routing command. This configuration is done automatically if you are using old-style slip address commands. However, you must configure it manually if you configure SLIP or PPP via the interface async command.
Note
This command does not have a no form.
Examples
The following example resets HDLC serial encapsulation on serial interface 1:
Router(config)# interface serial 1Router(config-if)# encapsulation hdlcThe following example enables PPP encapsulation on serial interface 0:
Router(config)# interface serial 0Router(config-if)# encapsulation pppIn the following example, async interface 1 is configured for PPP encapsulation:
Router# configure terminalConfiguring from terminal, memory, or network [terminal]?Enter configuration commands, one per line. End with CNTL/Z.Router(config)# interface async 1Router(config-if)# encapsulation pppRelated Commands
fddi burst-count
To allow the FCI card to preallocate buffers to handle bursty FDDI traffic (for example, Network File System (NFS) bursty traffic), use the fddi burst-count command in interface configuration mode. To revert to the default value, use the no form of this command.
fddi burst-count number
no fddi burst-count
Syntax Description
Defaults
3 buffers
Command Modes
Interface configuration
Command History
Usage Guidelines
This command applies to the FCI card only.
Note
Examples
The following example sets the number of buffers to 5:
Router(config)# interface fddi 0Router(config-if)# fddi burst-count 5fddi c-min
To set the C-Min timer on the pulse code modulation (PCM), use the fddi c-min command in interface configuration mode. To revert to the default value, use the no form of this command.
fddi c-min microseconds
no fddi c-min
Syntax Description
Defaults
1600 microseconds
Command Modes
Interface configuration
Command History
Usage Guidelines
This command applies to the processor connection management (CMT) only. You need extensive knowledge of the PCM state machine to tune this timer. Use this command when you run into PCM interoperability problems.
Examples
The following example sets the C-Min timer to 2000 microseconds:
Router(config)# interface fddi 0Router(config-if)# fddi c-min 2000Related Commands
fddi cmt-signal-bits
To control the information transmitted during the connection management (CMT) signaling phase, use the fddi cmt-signal-bits command in interface configuration mode.
fddi cmt-signal-bits signal-bits [phy-a | phy-b]
Syntax Description
signal-bits
A hexadecimal number preceded by 0x; for example, 0x208. The FDDI standard defines 10 bits of signaling information that must be transmitted, as follows:
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•
•
•
•
•
•
•
phy-a
(Optional) Selects Physical Sublayer A. The default is 0x008 (hexadecimal) or 00 0000 1000 (binary). Bits 1 and 2 are set to 00 to select Physical A. Bit 3 is set to 1 to indicate "accept any connection."
phy-b
(Optional) Selects Physical Sublayer B. The default is 0x20c (hexadecimal) or 10 0000 1100 (binary). Bits 1 and 2 are set to 10 to select Physical B. Bit 3 is set to 1 to indicate "accept any connection." Bit 9 is set to 1 to select MAC on output. The normal data flow on FDDI is input on Physical A and output on Physical B.
Defaults
The default signal bits for the phy-a and phy-b keywords are as follows:
•
•
Command Modes
Interface configuration
Command History
Usage Guidelines
If neither the phy-a nor phy-b keyword is specified, the signal bits apply to both physical connections.
Caution
Table 10 lists the physical types.
Table 10 FDDI Physical Type Bit Specifications
0
0
Physical A
1
0
Physical B
0
1
Physical S
1
1
Physical M
Table 11 lists the duration bits.
This command does not have a no form.
Examples
The following example sets the CMT signaling phase to signal bits 0x208 on both physical connections:
Router(config)# interface fddi 0Router(config-if)# fddi cmt-signal-bits 208fddi duplicate-address-check
To turn on the duplicate address detection capability on the FDDI, use the fddi duplicate-address-check command in interface configuration mode. To disable this feature, use the no form of this command.
fddi duplicate-address-check
no fddi duplicate-address-check
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
If you use this command, the Cisco IOS software will detect a duplicate address if multiple stations are sharing the same MAC address. If the software finds a duplicate address, it will shut down the interface.
Examples
The following example enables duplicate address checking on the FDDI:
Router(config)# interface fddi 0Router(config-if)# fddi duplicate-address-checkfddi encapsulate
To specify encapsulating bridge mode on the CSC-C2/FCIT interface card, use the fddi encapsulate command in interface configuration mode. To turn off encapsulation bridging and return the FCIT interface to its translational, nonencapsulating mode, use the no form of this command.
fddi encapsulate
no fddi encapsulate
Syntax Description
This command has no arguments or keywords.
Defaults
By default, the FDDI interface uses the SNAP encapsulation format defined in RFC 1042, Standard for the Transmission of IP Datagrams Over IEEE 802 Networks. It is not necessary to define an encapsulation method for this interface when using the CSC-FCI interface card.
Command Modes
Interface configuration
Command History
Usage Guidelines
The no fddi encapsulate command applies only to CSC-C2/FCIT interfaces, because the CSC-FCI interfaces are always in encapsulating bridge mode. The CSC-C2/FCIT interface card fully supports transparent and translational bridging for the following configurations:
•
•
•
The fddi encapsulate command puts the CSC-C2/FCIT interface into encapsulation mode when doing bridging. In transparent mode, the FCIT interface interoperates with earlier versions of the CSC-FCI encapsulating interfaces when performing bridging functions on the same ring.
Caution
The following protocols have problems when bridged between Token Ring and other media: Novell IPX, DECnet Phase IV, AppleTalk, VINES, XNS, and IP. Furthermore, the following protocols may have problems when bridged between FDDI and other media: Novell IPX and XNS. We recommend that these protocols be routed whenever possible.
Examples
The following example sets FDDI interface 1 on the CSC-C2/FCIT interface card to encapsulating bridge mode:
Router(config)# interface fddi 1Router(config-if)# fddi encapsulatefddi frames-per-token
To specify the maximum number of frames that the FDDI interface will transmit per token capture, use the fddi frames-per-token command in interface configuration mode. To revert to the default values, use the no form of this command.
fddi frames-per-token number
no fddi frames-per-token
Syntax Description
number
Maximum number of frames to transmit per token capture. Valid values are from 1 to 10. The default is 3.
Defaults
3 frames
Command Modes
Interface configuration
Command History
Usage Guidelines
Changing the value will increase or decrease the maximum number of frames that the FDDI interface can transmit when it receives a token. Increasing the value does not necessarily mean more frames will be transmitted on each token capture. This is heavily dependent on the traffic load of the specific interface.
When the interface captures a token, it transmits all of the frames that are queued in the interface's transmit ring, up to a maximum value specified by the fddi frames-per-token command.
If there are no frames ready for transmission, the token is passed on, and no frames are transmitted. If there are less than the fddi frames-per-token value in the transmit ring, all frames in the transmit ring are transmitted before the token is passed on. If there are more than the fddi frames-per-token value in the transmit ring, the specified value is transmitted before the token is passed on. The remaining frames in the transmit ring remain queued until the token is captured again.
Examples
The following example shows how to configure the FDDI interface to transmit four frames per token capture:
! Show fddi frames-per-token command options4700(config-if)# fddi frames-per-token ?<1-10> Number of frames per token, default = 3! Specify 4 as the maximum number of frames to be transmitted per token4700(config-if)# fddi frames-per-token 4fddi smt-frames
To enable the Station Management (SMT) frame processing capability on the FDDI, use the fddi smt-frames command in interface configuration mode. To disable this function and prevent the Cisco IOS software from generating or responding to SMT frames, use the no form of this command.
fddi smt-frames
no fddi smt-frames
Syntax Description
This command has no arguments or keywords.
Defaults
Enabled
Command Modes
Interface configuration
Command History
Usage Guidelines
Use the no form of this command to turn off SMT frame processing for diagnosing purposes. Use the fddi smt-frames command to reenable the feature.
Examples
The following example disables SMT frame processing:
Router(config)# interface fddi 0Router(config-if)# no fddi smt-framesfddi tb-min
To set the TB-Min timer in the physical connection management (PCM), use the fddi tb-min command in interface configuration mode. To revert to the default value, use the no form of this command.
fddi tb-min milliseconds
no fddi tb-min
Syntax Description
milliseconds
Number that sets the TB-Min timer value. The range is 0 to 65,535 milliseconds. The default is 100 milliseconds.
Defaults
100 milliseconds
Command Modes
Interface configuration
Command History
Usage Guidelines
This command applies to the processor connection management (CMT) only. Use this command when you run into PCM interoperability problems.
Note
Examples
The following example sets the TB-Min timer to 200 ms:
Router(config)# interface fddi 0Router(config-if)# fddi tb-min 200Related Commands
fddi tl-min-time
To control the TL-Min time (the minimum time to transmit a Physical Sublayer, or PHY line state, before advancing to the next physical connection management [PCM] state, as defined by the X3T9.5 specification), use the fddi tl-min-time command in interface configuration mode.
fddi tl-min-time microseconds
Syntax Description
Defaults
30 microseconds
Command Modes
Interface configuration
Command History
Usage Guidelines
Interoperability tests have shown that some implementations of the FDDI standard need more than 30 microseconds to sense a signal.
This command does not have a no form.
Examples
The following example changes the TL-Min time from 30 microseconds to 100 microseconds:
Router(config)# interface fddi 0Router(config-if)# fddi tl-min-time 100The following example changes the TL-Min time from 30 microseconds to 100 microseconds on a Cisco 7500 series router:
Router(config)# interface fddi 3/0Router(config-if)# fddi tl-min-time 100Related Commands
fddi t-out
To set the t-out timer in the physical connection management (PCM), use the fddi t-out command in interface configuration mode. To revert to the default value, use the no form of this command.
fddi t-out milliseconds
no fddi t-out
Syntax Description
milliseconds
Number that sets the timeout timer. The range is 0 to 65,535 ms. The default is 100 ms.
Defaults
100 milliseconds
Command Modes
Interface configuration
Command History
Usage Guidelines
This command applies to the processor connection management (CMT) only. Use this command when you run into PCM interoperability problems.
Note
Examples
The following example sets the timeout timer to 200 ms:
Router(config)# interface fddi 0Router(config-if)# fddi t-out 200Related Commands
fddi token-rotation-time
To control ring scheduling during normal operation and to detect and recover from serious ring error situations, use the fddi token-rotation-time command in interface configuration mode. To revert to the default value, use the no form of this command.
fddi token-rotation-time microseconds
no fddi token-rotation-time
Syntax Description
microseconds
Number that specifies the token rotation time (TRT). The range is 4000 to 165,000 microseconds. The default is 5000 microseconds.
Defaults
5000 microseconds
Command Modes
Interface configuration
Command History
Usage Guidelines
The FDDI standard restricts the allowed time to be greater than 4000 microseconds and less than 165,000 microseconds. As defined in the X3T9.5 specification, the value remaining in the TRT is loaded into the token holding timer (THT). Combining the values of these two timers provides the means to determine the amount of bandwidth available for subsequent transmissions.
Examples
The following example sets the rotation time to 24,000 microseconds:
Router(config)# interface fddi 0Router(config-if)# fddi token-rotation-time 24000The following example sets the rotation time to 24,000 microseconds on a Cisco 7500 series router:
Router(config)# interface fddi 3/0Router(config-if)# fddi token-rotation-time 24000fddi valid-transmission-time
To recover from a transient ring error, use the fddi valid-transmission-time command in interface configuration mode. To revert to the default value, use the no form of this command.
fddi valid-transmission-time microseconds
no fddi valid-transmission-time
Syntax Description
microseconds
Number that specifies the transmission valid timer (TVX) interval. The range is 2500 to 2,147,483,647 microseconds. The default is 2500 microseconds.
Defaults
2500 microseconds
Command Modes
Interface configuration
Command History
Examples
The following example changes the transmission timer interval to 3000 microseconds:
Router(config)# interface fddi 0Router(config-if)# fddi valid-transmission-time 3000The following example changes the transmission timer interval to 3000 microseconds on Cisco 7000 series routers or Cisco 7200 series routers:
Router(config)# interface fddi 3/0Router(config-if)# fddi valid-transmission-time 3000fdl
To set the Facility Data Link (FDL) exchange standard for CSU controllers or to set the FDL exchange standard for a T1 interface that uses Extended Super Frame (ESF) framing format, use the fdl command in controller configuration mode or ATM interface configuration mode. To disable FDL support or to specify that there is no ESF FDL, use the no form of this command.
Cisco MC3810 Multiservice Access Concentrator
fdl {att | ansi | both}
no fdl {att | ansi | both}
Cisco 2600 or 3600 Series Routers
fdl {att | ansi | all | none}
no fdl {att | ansi | all | none}
Syntax Description
Defaults
Disabled on the Cisco MC3810 multiservice access concentrator.
The default value is ansi on Cisco 2600 or 3600 series routers.
Command Modes
Controller configuration for the Cisco MC3810 multiservice access concentrator.
ATM interface configuration for the Cisco 2600 or 3600 series routers.
Command History
Usage Guidelines
Cisco MC3810 Multiservice Access Concentrator
You must configure this command on both T1 controllers if you want to support the CSU function on each T1 line. However, you must use the same facilities data link exchange standard as your service provider. You can have a different standard configured on each T1 controller.
Cisco 2600 or 3600 Series Routers
This command is available for T1 links only and sets the standard that will be followed for FDL messaging through a 4-Kbps out-of-band channel that a service provider uses to check for errors on the facility. You must use the same FDL exchange standard as your service provider. If the setting is not correct, the link may fail to come up. You can have a different standard configured on each T1 interface.
Note
Examples
Cisco MC3810 Multiservice Access Concentrator
The following example configures the ANSI T1.403 standard for both T1 controllers:
Router(config)# controller t1 0Router(config-controller)# fdl ansiRouter(config-controller)# exitRouter(config)# controller t1 1Router(config-controller)# fdl ansiCisco 2600 or 3600 Series Routers
In a Cisco 2600 or 3600 series router, the following example specifies both ANSI and AT&T standards for FDL exchange:
Router(config)# interface atm 0/2Router(config-if)# fdl allframe-relay
To configure Frame Relay payload compression for each Frame Relay port, use the frame-relay command in interface configuration mode. To terminate this form of payload compression over Frame Relay, use the no form of this command.
frame-relay payload-compression frf9 stac caim [element-number]
no frame-relay payload-compression
Syntax Description
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
Use the frame-relay payload-compression command to enable or disable payload compression on a point-to-point interface or subinterface. Use the frame-relay map command to enable or disable payload compression on a multipoint interface or subinterface.
Shut down the interface before changing encapsulation types. Although this is not required, shutting down the interface ensures the interface is reset for the new encapsulation.
Examples
The following example shows Frame Relay configured to use payload compression with the frf9 stac algorithm for CAIM hardware compression, using the installed data compression AIM daughtercard as the compression source:
Router(config-if)# frame-relay payload-compression frf9 stac caim 0Related Commands
frame-relay map
To enable Frame Relay compression on a data-link connection (DLC) basis, and to define mapping between a destination protocol address and the data-link connection identifier (DLCI) used to connect to the destination address, use the frame-relay map command in interface configuration mode. To deactivate Frame Relay compression, use the no form of this command.
frame-relay map {protocol protocol-address dlci} payload-compression frf9 stac caim [element-number]
no frame-relay map
Syntax Description
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
Many DLCIs known by an access server can be used to send data to many different places, but they are all multiplexed over one physical link. The Frame Relay map tells the Cisco IOS software how to get from a specific protocol and address pair to the correct DLCI.
Although you did not specified the IETF keyword during configuration, the map inherits the attributes set with the encapsulation frame-relay command so that all interfaces use IETF encapsulation.
Use the frame-relay map command to enable or disable payload compression on multipoint interfaces. Use the frame-relay payload-compression command to enable or disable payload compression on point-to-point interfaces.
The broadcast keyword provides two functions: It forwards broadcasts when multicasting is not enabled, and it simplifies the configuration of (Open Shortest Path First (OSPF) for nonbroadcast networks that will use Frame Relay.
The broadcast keyword might also be required for some routing protocols—for example, AppleTalk—that depend on regular routing table updates, especially when the router at the remote site is waiting for a routing update packet to arrive before adding the route. Network broadcasts are necessary if you intend to use routing protocols such as Routing Information Protocol (RIP) or OSPF running across the Frame Relay link.
The frame-relay map payload-compression frf9 stac caim 0 command enables compression on the Frame Relay link, but requires the caim 0 portion of the command. To display Frame Relay output, do not use the show compress command; use the show controllers serial 0/0 command.
Examples
The following example shows configuration of the frame-relay map payload-compression command using the data compression AIM daughtercard for compression mapping the destination address 1.1.1.2 to DLCI 16:
Router(config-if)# frame-relay map ip 10.1.1.2 16 broadcast payload-compression frf9 stac caim 0Related Commands
framing
To select the frame type for the T1 or E1 data line, use the framing command in controller configuration mode.
Syntax for T1 Lines
framing {sfadm | esfadm}
Syntax for E1 Lines
framing {crc4adm | pcm30adm | clear e1}
Syntax Description
Defaults
Extended Super Frame for a T1 line
CRC4 disabled framing for an E1 line
Command Modes
Controller configuration
Command History
Usage Guidelines
Use this command in configurations in which the router or access server is intended to communicate with T1 or E1 fractional data lines. The service provided determines which framing type, either sf, esf, or crc4 is required for your T1 or E1 circuit.
Examples
The following example selects Extended Super Frame as the T1 frame type:
framing esfadmRelated Commands
lbo
Specifies the distance of the cable from the routers to the network equipment.
Selects the line-code type for a T1 or E1 line.
framing (E1/T1 controller)
To select the frame type for the E1 or T1 data line, use the framing command in controller configuration mode.
T1 Lines
framing {sf | esf}
E1 Lines
framing {crc4 | no-crc4} [australia]
Syntax Description
Defaults
Super frame is the default on a T1 line.
CRC4 frame is the default on an E1 line.
Command Modes
Controller configuration
Usage Guidelines
Use this command in configurations where the router or access server is intended to communicate with T1 or E1 fractional data lines. The service provider determines the framing type (sf, esf, or crc4) required for your T1/E1 circuit.
This command does not have a no form.
Examples
The following example selects extended Super Frame as the T1 frame type:
Router(config-controller)# framing esfRelated Commands
Specifies the distance of the cable from the routers to the network equipment.
Selects the linecode type for T1 or E1 line.
framing (E3/T3 interface)
To specify E3 or T3 line framing for a PA-E3 or PA-T3 port adapter, use the framing command in interface configuration mode. To return to the default G.751 framing or C-bit framing, use the no form of this command.
PA-E3
framing {bypass | g751}
no framing
PA-T3
framing {c-bit | m13 | bypass}
no framing
Syntax Description
Defaults
G.751 framing for PA-E3
C-bit framing for PA-T3
Command Modes
Interface configuration
Command History
Usage Guidelines
The default framing is described in the ITU-T Recommendation G.751.
Note
When the framing mode is bypass, the E3 frame data is not included in the E3 frame, just the data.
When the framing mode is bypass, the T3 frame data is not included in the T3 frame, just the data.
If you use the bypass keyword, scrambling must be set to the default (disabled), the DSU mode must be set to the default (0), and the DSU bandwidth must be set to the default (44736).
To verify the framing mode configured on the interface, use the show controllers serial command in EXEC mode.
Examples
The following example sets the framing mode to bypass on interface 1/0/0:
Router(config)# interface serial 1/0/0Router(config-if)# framing bypassRelated Commands
framing (T3 controller)
To specify T3 line framing used by the CT3 feature board in a Cisco AS5800 universal access server, or by the CT3IP port adapter in Cisco 7500 series routers, use the framing command in controller configuration mode. To restore the default framing type, use the no form of this command.
Cisco AS5800 Universal Access Server
framing {c-bit | m23}
no framing
Cisco 7500 Series Routers
framing {c-bit | m23 | auto-detect}
no framing
Syntax Description
Defaults
c-bit for CT3 in a Cisco AS5800
auto-detect for CT3IP in a Cisco 7500 series router
Command Modes
Controller configuration
Command History
Usage Guidelines
If you do not specify the framing command, the default auto-detect is used by the CT3IP to automatically determine the framing type received from the far-end equipment.
Because the CT3IP supports the Application Identification Channel (AIC) signal, the setting for the framing might be overridden by the CT3IP firmware.
You can also set the framing for each T1 channel by using the t1 framing controller configuration command.
Examples
The following example sets the framing for the CT3IP to C-bit:
Router(config)# controller t3 9/0/0Router(config-controller)# framing c-bitRelated Commands
Specifies the type of framing used by the T1 channels on the CT3IP in Cisco 7500 series routers.
full-duplex
To specify full-duplex mode on full-duplex single-mode and multimode port adapters, use the full-duplex command in interface configuration mode. To restore the default half-duplex mode, use the no form of this command.
full-duplex
no full-duplex
Syntax Description
This command has no arguments or keywords.
Defaults
Half-duplex mode is the default mode on a Cisco 7500 series router, a Fast Ethernet Interface Processor (FEIP), and for serial interfaces that are configured for bisynchronous tunneling.
Command Modes
Interface configuration
Command History
11.1
This command was introduced.
11.3
This command was modified to include information on FDDI full-duplex, single-mode and multimode port adapters.
Usage Guidelines
Use this command if the equipment on the other end is capable of full-duplex mode.
This command specifies full-duplex mode on full-duplex single-mode and multimode port adapters available on the following networking devices:
•
•
•
•
Refer to the Cisco Product Catalog for hardware compatibility information and for specific model numbers of port adapters.
To enable half-duplex mode, use the no full-duplex or half-duplex commands.
Caution
Router(config)# interface fastethernet 0
Router(config-if)# full-duplex
Please use duplex command to configure duplex mode
Router(config-if)#
Router(config-if)# half-duplex
Please use duplex command to configure duplex mode
Support for this Command
Use the question mark (?) command to find out which port adapters support this command. If the interface does not support full-duplex, an informational message similar to the one shown below is displayed, and no changes are made to the interface. To determine if the interface supports full-duplex, use the show interfaces command. For example, the following message is displayed if the interface does not support full-duplex:
% interface does not support full-duplex.Use on FDDI
Full-duplex on the FDDI full-duplex port adapters allows an FDDI ring with exactly two stations to transform the ring into a full-duplex, point-to-point topology. To operate in full-duplex mode, there must be only two stations on the ring, the two stations must be capable of operating in full-duplex mode, and both stations must complete a full-duplex autoconfiguration protocol. There is no FDDI token in full-duplex mode. Refer to the Cisco Product Catalog for specific model numbers of port adapters.
Full-duplex autoconfiguration protocol allows an FDDI station to dynamically and automatically operate in either half-duplex (or ring) or full-duplex mode, and ensures that the stations fall back to ring mode when a configuration change occurs, such as a third station joining the ring.
After booting up, the FDDI stations begin operation in half-duplex mode. While the station performs the full-duplex autoconfiguration protocol, the station continues to provide data-link services to its users. Under normal conditions, the transition between half-duplex mode and full-duplex mode is transparent to the data-link users. The data-link services provided by full-duplex mode are functionally the same as the services provided by half-duplex mode.
If you change the full-duplex configuration (for example from disabled to enabled) on supported interfaces, the interface resets.
Examples
The following example configures full-duplex mode on the Cisco 7000 series routers:
Router(config)# interface fastethernet 0/1Router(config-if)# full-duplexThe following example specifies full-duplex binary synchronous communications (Bisync) mode:
Router(config)# interface serial 0Router(config-if)# encapsulation bstunRouter(config-if)# full-duplexThe following example enables full-duplex mode on FDDI interface 0:
Router(config)# interface fddi 0/1/0Router(config-if)# full-duplexRelated Commands
Specifies half-duplex mode on an SDLC interface or on the FDDI full-duplex, single-mode port adapter and FDDI full-duplex, multimode port adapter on the Cisco 7200 series and Cisco 7500 series routers.
Configures an interface type and enters interface configuration mode.
Selects a particular Fast Ethernet interface for configuration.
interface serial
Specifies a serial interface created on a channelized E1 or channelized T1 controller (for ISDN PRI, CAS, or robbed-bit signaling).
Displays statistics for all interfaces configured on the router or access server.
Displays information about the FDDI interface.
half-duplex
To specify half-duplex mode on an Synchronous Data Link Control (SDLC) interface or on the FDDI full-duplex, single-mode port adapter and FDDI full-duplex, multimode port adapter on the Cisco 7200 series and Cisco 7500 series routers, use the half-duplex command in interface configuration mode. To reset the interface to full-duplex mode, use the no form of this command.
half-duplex
no half-duplex
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
11.1
This command was introduced.
11.3
This command was modified to include information on FDDI full-duplex, single-mode and multimode port adapters.
Usage Guidelines
SDLC Interfaces
The half-duplex command is used to configure an SDLC interface for half-duplex mode and is used on a variety of port adapters. Use the question mark (?) command to find out which port adapters support this command.
Note
Caution
Router(config)# interface fastethernet 0
Router(config-if)# full-duplex
Please use duplex command to configure duplex mode
Router(config-if)#
Router(config-if)# half-duplex
Please use duplex command to configure duplex mode
Enabling Full-Duplex Mode
To enable full-duplex mode, use the no half-duplex or full-duplex commands.
Note
Port Adapters
Refer to the Cisco Product Catalog for specific model numbers of port adapters.
Examples
The following example configures an SDLC interface for half-duplex mode:
Router(config-if)# encapsulation sdlc-primaryRouter(config-if)# half-duplexRelated Commands
Specifies full-duplex mode on full-duplex single-mode and multimode port adapters.
half-duplex controlled-carrier
To place a low-speed serial interface in controlled-carrier mode, instead of constant-carrier mode, use the half-duplex controlled-carrier command in interface configuration mode. To return the interface to constant-carrier mode, use the no form of this command.
half-duplex controlled-carrier
no half-duplex controlled-carrier
Syntax Description
This command has no arguments or keywords.
Defaults
Constant-carrier mode, where Data Carrier Detect (DCD) is held constant and asserted by the DCE half-duplex interface.
Command Modes
Interface configuration
Command History
Usage Guidelines
This command applies only to low-speed serial DCE interfaces in half-duplex mode. Configure a serial interface for half-duplex mode by using the half-duplex command. Refer to the Cisco Product Catalog for specific model numbers of networking devices which support serial interfaces.
Controlled-carrier operation means that the DCE interface has DCD deasserted in the quiescent state. When the interface has something to transmit, it asserts DCD, waits a user-configured amount of time, then starts the transmission. When the interface has finished transmitting, it waits a user-configured amount of time and then deasserts DCD.
Examples
The following examples place the interface in controlled-carrier mode and back into constant-carrier operation.
This example shows changing to controlled-carrier mode from the default of constant-carrier operation:
Router(config)# interface serial 2Router(config-if)# half-duplex controlled-carrierThis example shows changing to constant-carrier operation from controlled-carrier mode:
Router(config)# interface serial 2Router(config-if)# no half-duplex controlled-carrierRelated Commands
Tunes half-duplex timers.
Specifies the mode of a slow-speed serial interface on a router as either synchronous or asynchronous.
half-duplex timer
To tune half-duplex timers, use the half-duplex timer command in interface configuration mode. To return to the default value for that parameter, use the no form of this command along with the appropriate keyword.
half-duplex timer {cts-delay value | cts-drop-timeout value | dcd-drop-delay value | dcd-txstart-delay value | rts-drop-delay value | rts-timeout value | transmit-delay value}
no half-duplex timer {cts-delay value | cts-drop-timeout value | dcd-drop-delay value | dcd-txstart-delay value | rts-drop-delay value | rts-timeout value | transmit-delay value}
Syntax Description
Defaults
The default cts-delay value is 0 ms.
The default cts-drop-timeout value is 250 ms.
The default dcd-drop-delay value is 100 ms.
The default dcd-txstart-delay value is 100 ms.
The default rts-drop-delay value is 3 ms.
The default rts-timeout value is 3 ms.
The default transmit-delay value is 0 ms.
Command Modes
Interface configuration
Command History
Usage Guidelines
Tuning Half-Duplex Timers
The half-duplex timer command is used to tune half-duplex timers. With these timer tuning commands you can adjust the timing of the half-duplex state machines to suit the particular needs of their half-duplex installation.
You can configure more than one option using this command, but each option must be specified as a separate command.
Note
Value Ranges
The range of values for the cts-delay and rts-timeout keywords are dependent on the serial interface hardware.
Examples
The following example set the cts-delay timer to 10 ms and the transmit-delay timer to 50 ms:
Router(config)# interface serial 2Router(config-if)# half-duplex timer cts-delay 10Router(config-if)# half-duplex timer transmit-delay 50Related Commands
hold-queue
To limit the size of the IP output queue on an interface, use the hold-queue command in interface configuration mode. To restore the default values for an interface, use the no form of this command with the appropriate keyword.
hold-queue length {in | out}
no hold-queue {in | out}
Syntax Description
Defaults
The default input hold-queue limit is 75 packets.
The default output hold-queue limit is 40 packets.
For asynchronous interfaces the default is 10 packets.
These limits prevent a malfunctioning interface from consuming an excessive amount of memory. There is no fixed upper limit to a queue size.
Command Modes
Interface configuration
Command History
Usage Guidelines
Back-to-Back Routing Updates
The default of 10 packets allows the Cisco IOS software to queue a number of back-to-back routing updates. This is the default for asynchronous interfaces only; other media types have different defaults.
Hold Queues and Priority Queueing
The hold queue stores packets received from the network that are waiting to be sent to the client. It is recommended that the queue size not exceed ten packets on asynchronous interfaces. For most other interfaces, queue length should not exceed 100.
The input hold queue prevents a single interface from flooding the network server with too many input packets. Further input packets are discarded if the interface has too many input packets outstanding in the system.
If priority output queueing is being used, the length of the four output queues is set using the priority-list global configuration command. The hold-queue command cannot be used to set an output hold queue length in this situation.
For slow links, use a small output hold-queue limit. This approach prevents storing packets at a rate that exceeds the transmission capability of the link. For fast links, use a large output hold-queue limit. A fast link may be busy for a short time (and thus require the hold queue), but can empty the output hold queue quickly when capacity returns.
To display the current hold queue setting and the number of packets discarded because of hold queue overflows, use the show interfaces command in EXEC mode.
Caution
Examples
The following example sets a small input queue on a slow serial line:
Router(config)# interface serial 0Router(config-if)# hold-queue 30 iRelated Commands
hssi external-loop-request
To allow the router to support a CSU/DSU that uses the LC signal to request a loopback from the router, use the hssi external-loop-request command in interface configuration mode. To disable the feature, use the no form of this command.
hssi external-loop-request
no hssi external-loop-request
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
The HSA applique on the High Speed Serial Interface (HSSI) contains an LED that indicates the LA, LB, and LC signals transiting through the devices. The CSU/DSU uses the LC signal to request a loopback from the router. The CSU/DSU may want to do this so that its own network management diagnostics can independently check the integrity of the connection between the CSU/DSU and the router.
Use this command to enable a two-way, internal, and external loopback request on HSSI from the CSU/DSU.
Caution
Examples
The following example enables a CSU/DSU to use the LC signal to request a loopback from the router:
Router(config-if)# hssi external-loop-requesthssi internal-clock
To convert the High Speed Serial Interface (HSSI) into a clock master, use the hssi internal-clock command in interface configuration mode. To disable the clock master mode, use the no form of this command.
hssi internal-clock
no hssi internal-clock
Syntax Description
This command has no arguments or keywords.
Defaults
Disabled
Command Modes
Interface configuration
Command History
Usage Guidelines
Use this command in conjunction with the HSSI null-modem cable to connect two Cisco routers together with HSSI. You must configure this command at both ends of the link, not just one.
Note
Examples
The following example converts the HSSI interface into a clock master:
Router(config-if)# hssi internal-clockhub
To enable and configure a port on an Ethernet hub of a Cisco 2505 or Cisco 2507 router, use the hub command in global configuration mode.
hub ethernet number port [end-port]
Syntax Description
Defaults
No hub ports are configured.
Command Modes
Global configuration
Command History
Usage Guidelines
This command does not have a no form.
Examples
The following example enables port 1 on hub 0:
Router# hub ethernet 0 1Router(config-hub)# no shutdownThe following example enables ports 1 through 8 on hub 0:
Router# hub ethernet 0 1 8Router(config-hub)# no shutdownRelated Commands
ignore-dcd
To configure the serial interface to monitor the 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 Data Carrier Detect (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 Data Set Ready (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 configures 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 LL pin when in DCE mode, use the ingnore-hw local-loopback command in interface configuration mode. To return to the default, 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, which momentarily causes the interface to enter loopback mode. The end result of this behavior is the loss of SDLLC sessions.
Note
Examples
The following example shows how to disable the monitoring of the LL pin when in DCE mode:
Router#configure terminalRouter(config)#interface serial 2interface
To configure an interface type and enter interface configuration mode, use the interface command in global configuration mode.
interface type number [name-tag]
Cisco 7200 Series and Cisco 7500 Series with a Packet over SONET Interface Processor
interface type 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 [ethernet | serial]
Cisco 4000 Series with Channelized T1 or E1 and the Cisco MC3810
interface serial number:channel-group
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 12.
number
Port, connector, or interface card number. On a Cisco 4000 series router, specifies the 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 RLM feature.
slot
Number of the slot being configured. Refer to the appropriate hardware manual for slot and port information.
port
Number of the port being configured. Refer to the appropriate hardware manual for slot and port information.
port-adapter
Number of the port adapter being configured. Refer to the appropriate hardware manual for information about port adapter compatibility.
ethernet
(Optional) Ethernet IEEE 802.3 interface.
serial
(Optional) Serial interface.
:channel-group
Cisco 4000 series routers specify the T1 channel group number in the range of 0 to 23 defined with the channel-group controller configuration command. On a dual port card, it is possible to run channelized on one port and primary rate on the other port.
Cisco MC3810 specifies the T1/E1 channel group number in the range of 0 to 23 defined with the channel-group controller configuration command.
.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 Configuration Guide.
There is no correlation between the number of the physical serial interface and the number of the logical LAN Extender interface. These interfaces can have the same or different numbers.
This command does not have a no form.
Examples
The following example configures serial interface 0 with PPP encapsulation:
Router(config)# interface serial 0Router(config-if)# encapsulation pppThe following example enables 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 131.108.1.1 255.255.255.0The following example for the Cisco 7500 series router shows the interface configuration command for Ethernet port 4 on the Ethernet Interface Processor (EIP) that is installed in (or recently removed from) slot 2:
Router(config)# interface ethernet 2/4The following example begins configuration on 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 shows how a partially meshed Frame Relay network can be configured. In this example, subinterface serial 0.1 is configured as a multipoint subinterface with three Frame Relay permanent virtual connections (PVCs) associated, and subinterface serial 0.2 is configured as a point-to-point subinterface.
Router(config)# interface serial 0Router(config-if)# encapsulation frame-relayRouter(config)# interface serial 0.1 multipointRouter(config-if)# ip address 131.108.10.1 255.255.255.0Router(config-if)# frame-relay interface-dlci 42 broadcastRouter(config-if)# frame-relay interface-dlci 53 broadcastRouter(config)# interface serial 0.2 point-to-pointRouter(config-if)# ip address 131.108.11.1 255.255.0Router(config-if)# frame-relay interface-dlci 59 broadcastThe following example configures 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)# interface serial 4/1:0Router(config-if)# ip address 131.108.13.1 255.255.255.0Router(config-if)# encapsulation pppThe following example configures LAN Extender interface 0:
Router(config)# interface lex 0Related Commands
interface ctunnel
To create a virtual interface to transport IP over a Connectionless Network Service (CLNS) tunnel (CTunnel), use the interface ctunnel command in global configuration mode. To remove the virtual interface, use the no form of this command.
interface ctunnel interface-number
no interface ctunnel interface-number
Syntax Description
Defaults
No virtual interface is configured.
Command Modes
Global configuration
Command History
Usage Guidelines
When configuring an IP over CLNS tunnel, you must first create a virtual interface. In the following example, the interface ctunnel command is used to create the virtual interface.
Examples
The following example configures a CTunnel from one router to another and shows the CTunnel destination set to 49.0001.1111.1111.1111.00:
interface ctunnel 301ip address 10.0.0.3 255.255.255.0ctunnel destination 49.0001.1111.1111.1111.00Related Commands
