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Table of Contents

delay
dce-terminal-timing enable
description (controller)
down-when-looped
dsu bandwidth
dsu mode
dte-invert-txc
duplex
early-token-release
encapsulation
fddi burst-count
fddi c-min
fddi cmt-signal-bits
fddi duplicate-address-check
fddi encapsulate
fddi frames-per-token
fddi smt-frames
fddi tb-min
fddi tl-min-time
fddi t-out
fddi token-rotation-time
fddi valid-transmission-time
fdl
framing (E1/T1 controller)
framing (E3/T3 interface)
framing (T3 controller)
full-duplex
half-duplex
half-duplex controlled-carrier
half-duplex timer
hold-queue
hssi external-loop-request
hssi internal-clock
hub
ignore-dcd
ignore-hw local-loopback

delay

To set a delay value for an interface, use the delay interface configuration command. Use the no form of this command to restore the default delay value.

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.

Default

Default delay values may be displayed with the EXEC command show interfaces.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Example

The following example sets a 30,000-microsecond delay on serial interface 3:

interface serial 3
 delay 30000

Related Commands

You can use the master indexes or search online to find documentation of related commands.

show interfaces

dce-terminal-timing enable

When running the line at high speeds and long distances, use the dce-terminal-timing enable interface configuration command to prevent phase shifting of the data with respect to the clock. If SCTE is not available from the DTE, use no form of this command, which causes the DCE to 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 keywords or arguments.

Default

DCE uses its own clock.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

On the Cisco 4000 platform, 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.

Example

The following example prevents phase shifting of the data with respect to the clock:

interface serial 0
 dce-terminal-timing enable

description (controller)

Use the description controller configuration command to add a description to an E1 or T1 controller or the Channelized T3 Interface Processor (CT3IP) in Cisco 7500 series routers. Use the no form of this command to remove the description.

description string
no description

Syntax Description

string

Comment or a description to help you remember what is attached to the interface. Up to 80 characters.

Default

No description is added.

Command Mode

Controller configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

This command was modified in Cisco IOS Release 11.3 to include the CT3IP controller.

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 MIP interfaces only and appears in the output of the show controller t3, show controller e1, show controller t1, and more system:running-config EXEC commands.

Example

The following example describes a 3174 controller:

controller t1
  description 3174 Controller for test lab

Related Commands

You can use the master indexes or search online to find documentation of related commands.

show controller e1
show controller t1
show controller t3
more system:running-config

down-when-looped

Use the down-when-looped interface configuration command to configure an interface to inform the system it is down when loopback is detected.

down-when-looped

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

This command is valid for HDLC or PPP encapsulation on serial and HSSI interfaces.

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, down-when-looped should not be configured; otherwise, packets will not be transmitted out the interface that is being tested.

Example

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.

interface serial0
  encapsulation hdlc
  down-when-looped

Related Commands

You can use the master indexes or search online to find documentation of related commands.

backup interface serial
loopback (interface)

dsu bandwidth

To specify the maximum allowable bandwidth used by the PA-E3 port adapter and PA-T3 port adapter, use the dsu bandwidth interface configuration command. 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 varies for different port adapters.

Default

34010 kbps for PA-E3

44736  kbps for PA-T3

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.1 CA.

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 controller serial EXEC command.

Example

The following example sets the DSU bandwidth to 16000 kbps on interface 1/0/0:

interface serial 1/0/0
  dsu bandwidth 16000

Related Commands

You can use the master indexes or search online to find documentation of related commands.

show controllers serial

dsu mode

To specify the interoperability mode used by a PA-E3 port adapter or PA-T3 port adapter, use the dsu mode interface configuration command. To return to the default mode, use the no form of this command.

dsu mode {0 | 1 | 2}
no dsu mode

Syntax Description

0

Sets the interoperability mode to 0. This is the default. Specify mode 0 to connect a PA-E3 port adapter to another PA-E3 port adapter or to a Digital Link DSU (DL3100). Use mode 0 to connect a PA-T3 port adapter to another PA-T3 port adapter or to a Digital Link DSU (DL3100).

1

Sets the interoperability mode to 1. Specify mode 1 to connect a PA-E3 port adapter or PA-T3 port adapter to a Kentrox DSU.

2

Sets the interoperability mode to 2. Specify mode 2 to connect a PA-T3 port adapter to a Larscom DSU.

Default

0 mode

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.1 CA.

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 port adapter or a PA-T3 port adapter. Use mode 0 to connect a PA-E3 port adapter to another PA-E3 port adapter or to a Digital Link DSU (DL3100). Use mode 0 to connect a PA-T3 port adapter to another PA-T3 port adapter or to a Digital Link DSU (DL3100). Use mode 1 to connect a PA-E3 port adapter 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.

The dsu mode command enables and improves interoperability with other DSUs.

To verify the DSU mode configured on the interface, use the show controller serial EXEC command.

Example

The following example sets the DSU mode to 1 on interface 1/0/0:

interface serial 1/0/0
  dsu mode 1

Related Commands

You can use the master indexes or search online to find documentation of related commands.

show controllers serial

dte-invert-txc

Use the dte-invert-txc interface configuration command to invert the TXC clock signal received from the DCE. Use the no form of this command if the DCE accepts SCTE from the DTE.

dte-invert-txc
no dte-invert-txc

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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. This 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.

Example

The following example inverts the TXC on serial interface 0:

interface serial 0
 dte-invert-txc

duplex

To configure the duplex operation on an interface, use the duplex interface configuration command. Use the no form of this command to return the system to half-duplex mode, which is the system default.

duplex {full | half | auto}
no duplex

Syntax Description

full

Specifies full-duplex operation.

half

Specifies half-duplex operation.

auto

Specifies the auto negotiation capability. The interface automatically operates at half or full duplex, depending on environmental factors, such as the type of media and transmission speeds for the peer routers, hubs, and switches used in the network configuration.

Default

Half-duplex mode

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.2(10)P.

To use the auto-negotiation capability (that is, detect speed and duplex modes automatically), you must set both speed and duplex to auto. Setting speed to auto negotiates speed only, and setting duplex to auto negotiates duplex only.

Table 7 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.


Table 7: Relationship between Duplex and Speed Commands
Duplex Commands Speed Commands Resulting System Action

duplex auto

speed auto

Auto negotiates both speed and duplex modes.

duplex auto

speed 100 or speed 10

Auto negotiates both speed and duplex modes.

duplex half or duplex full

speed auto

Auto negotiates both speed and duplex modes.

duplex half

speed 10

Forces 10 Mbps and half duplex.

duplex full

speed 10

Forces 10 Mbps and full duplex.

duplex half

speed 100

Forces 100 Mbps and half duplex.

duplex full

speed 100

Forces 100 Mbps and full duplex.

For the Cisco AS5300, the duplex {full | half | auto} command syntax replaces the following two earlier duplex commands:

You will get the following error messages if you try to use these commands on a Cisco AS5300:

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

Example

The following example shows the different duplex configuration options you can configure on a Cisco AS5300:

router# configure terminal 
Enter configuration commands, one per line.  End with CNTL/Z.
router(config)# interface fastethernet 0
router(config-if)# duplex ?
  auto  Enable AUTO duplex configuration
  full  Force full duplex operation
  half  Force half-duplex operation

Related Commands

You can use the master indexes or search online to find documentation of related commands.

duplex
interface fastethernet
show controller fastethernet
speed

early-token-release

To enable early token release on Token Ring interfaces, use the early-token-release interface configuration command. Once enabled, use the no form of this command to disable this feature.

early-token-release
no early-token-release

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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:

interface tokenring 1
  early-token-release

On 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:

interface tokenring 4/1
  early-token-release

encapsulation

To set the encapsulation method used by the interface, use the encapsulation interface configuration command.

encapsulation encapsulation-type

Syntax Description

encapsulation-type

Encapsulation type; one of the following keywords:

· atm-dxi---Asynchronous Transfer Mode-Data Exchange Interface.

· bstun---Block Serial Tunnel.

· frame-relay---Frame Relay (for serial interface).

· hdlc---High-Level Data Link Control (HDLC) protocol for serial interface. This encapsulation method provides the synchronous framing and error detection functions of HDLC without windowing or retransmission.

· isl --- Inter-Switch Link (ISL) (for virtual LANs)

· lapb---X.25 LAPB DTE operation (for serial interface).

· ppp---Point-to-Point Protocol (PPP) (for serial interface).

· sde---IEEE 802.10 Security Data Exchange.

· sdlc---IBM serial SNA.

· sdlc-primary---IBM serial SNA (for primary serial interface).

· sdlc-secondary---IBM serial SNA (for secondary serial interface).

· smds---Switched Multimegabit Data Services (SMDS) (for serial interface).

Default

The default depends on the type of interface. For example, a synchronous serial interface defaults to HDLC.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Examples

The following example resets HDLC serial encapsulation on serial interface 1:

interface serial 1
 encapsulation hdlc

The following example enables PPP encapsulation on serial interface 0:

interface serial 0
  encapsulation ppp

Related Commands

You can use the master indexes or search online to find documentation of related commands.

keepalive
ppp

ppp authentication
slip

fddi burst-count

Use the fddi burst-count interface configuration command to allow the FCI card to preallocate buffers to handle bursty FDDI traffic (for example, NFS bursty traffic). Use the no form of this command to revert to the default value.

fddi burst-count number
no fddi burst-count

Syntax Description

number

Number of preallocated buffers in the range from 1 to 10. The default is 3  buffers.

Default

3 buffers

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

This command applies to the FCI card only. The microcode software version should not be 128.45 or 128.43.

Example

The following example sets the number of buffers to 5:

interface fddi 0
 fddi burst-count 5

fddi c-min

To set the C-Min timer on the PCM, use the fddi c-min interface configuration command. Use the no form of this command to revert to the default value.

fddi c-min microseconds
no fddi c-min

Syntax Description

microseconds

Sets the timer value in microseconds. The default is 1600 microseconds.

Default

1600 microseconds

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

This command applies to the processor 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.

Example

The following example sets the C-Min timer to 2000 microseconds:

interface fddi 0
 fddi c-min 2000

Related Commands

You can use the master indexes or search online to find documentation of related commands.

fddi tb-min
fddi tl-min-time
fddi t-out

fddi cmt-signal-bits

To control the information transmitted during the connection management (CMT) signaling phase, use the fddi cmt-signal-bits interface configuration command.

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 ten bits of signaling information that must be transmitted, as follows:

· bit 0---Escape bit. Reserved for future assignment by the FDDI standards committee.

· bits 1 and 2---Physical type, as defined in Table 8.

· bit 3---Physical compatibility. Set if topology rules include the connection of a physical-to-physical type at the end of the connection.

· bits 4 and 5---Link confidence test duration; set as defined in Table 9.

· bit 6---Media Access Control (MAC) available for link confidence test.

· bit 7---Link confidence test failed. The setting of bit 7 indicates that the link confidence was failed by the Cisco end of the connection.

· bit 8---MAC for local loop.

· bit 9---MAC on physical output.

phy-a

(Optional) Selects Physical Sublayer A.

phy-b

(Optional) Selects Physical Sublayer B.

Defaults

The default signal bits for the phy-a and phy-b keywords are as follows:

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

If neither the phy-a nor phy-b keyword is specified, the signal bits apply to both physical connections.


Note Use of the fddi cmt-signal-bits configuration command is not recommended under normal operations. This command is used when debugging specific CMT implementation issues.

Table 8 lists the physical types.


Table 8: FDDI Physical Type Bit Specifications
Bit 2 Bit 1 Physical Type

0

0

Physical A

1

0

Physical B

0

1

Physical S

1

1

Physical M

Table 9 lists the duration bits.


Table 9: FDDI Link Confidence Test Duration Bit Specification
Bit 5 Bit 4 Test Duration

0

0

Short test (default 50 ms)

1

0

Medium test (default 500 ms)

0

1

Long test (default 5 seconds)

1

1

Extended test (default 50 seconds)

Example

The following example sets the CMT signaling phase to signal bits 0x208 on both physical connections:

interface fddi 0
 fddi cmt-signal-bits 208

fddi duplicate-address-check

Use the fddi duplicate-address-check interface configuration command to turn on the duplicate address detection capability on the FDDI. Use the no form of this command to disable this feature.

fddi duplicate-address-check
no fddi duplicate-address-check

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

The following example enables duplicate address checking on the FDDI:

interface fddi 0
 fddi duplicate-address-check

fddi encapsulate

Use the fddi encapsulate interface configuration command to specify encapsulating bridge mode on the CSC-C2/FCIT interface card. Use the no form of this command to turn off encapsulation bridging and return the FCIT interface to its translational, nonencapsulating mode.

fddi encapsulate
no fddi encapsulate

Syntax Description

This command has no arguments or keywords.

Default

The FDDI interface by default uses the SNAP encapsulation format defined in RFC  1042. It is not necessary to define an encapsulation method for this interface when using the CSC-FCI interface card.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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 command fddi encapsulate 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 Bridging between dissimilar media presents several problems that can prevent communications from occurring. These problems include bit-order translation (or usage of MAC addresses as data), maximum transfer unit (MTU) differences, frame status differences, and multicast address usage. Some or all of these problems might be present in a multimedia bridged LAN and might prevent communication from taking place. These problems are most prevalent when bridging between Token Rings and Ethernets or between Token Rings and FDDI nets. This is because of the different way Token Ring is implemented by the end nodes.

The following protocols have problems when bridged between Token Ring and other media: Novell IPX, DECnet Phase IV, AppleTalk, VINES, XNS, and IP. Further, 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.

Example

The following example sets FDDI interface 1 on the CSC-C2/FCIT interface card to encapsulating bridge mode:

interface fddi 1
 fddi encapsulate

fddi 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 interface configuration command. Us the no form of this command to revert to the default value.

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.

Default

3 frames

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.2 P.

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.

Example

The following example shows how to configure the FDDI interface to transmit four frames per token capture:

! Show fddi frames-per-token command options
    4700(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 token
    4700(config-if)#fddi frames-per-token 4

fddi smt-frames

To enable the SMT frame processing capability on the FDDI, use the fddi smt-frames interface configuration command. Use the no form of this command to disable this function and prevent the Cisco IOS software from generating or responding to SMT frames.

fddi smt-frames
no fddi smt-frames

Syntax Description

This command has no arguments or keywords.

Default

Enabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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.

Example

The following example disables SMT frame processing:

interface fddi 0
 no fddi smt-frames

fddi tb-min

To set the TB-Min timer in the physical connection management (PCM), use the fddi tb-min interface configuration command. Use the no form of this command to revert to the default value.

fddi tb-min milliseconds
no fddi tb-min

Syntax Description

milliseconds

Number that sets the TB-Min timer value. The default is 100 milliseconds.

Default

100 milliseconds

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

This command applies to the processor 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.

Example

The following example sets the TB-Min timer to 200 milliseconds:

interface fddi 0
 fddi tb-min 200

Related Commands

You can use the master indexes or search online to find documentation of related commands.

fddi c-min
fddi tl-min-time
fddi t-out

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 interface configuration command.

fddi tl-min-time microseconds

Syntax Description

microseconds

Number that specifies the time used during the connection management (CMT) phase to ensure that signals are maintained for at least the value of TL-Min so the remote station can acquire the signal. The default is 30 microseconds.

Default

30 microseconds

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Interoperability tests have shown that some implementations of the FDDI standard need more than 30 microseconds to sense a signal.

Examples

The following example changes the TL-Min time from 30 microseconds to 100 microseconds:

interface fddi 0
  fddi tl-min-time 100

The following example changes the TL-Min time from 30 microseconds to 100 microseconds on a Cisco 7500 series router:

interface fddi 3/0
  fddi tl-min-time 100

Related Commands

You can use the master indexes or search online to find documentation of related commands.

fddi c-min
fddi tl-min-time
fddi t-out

fddi t-out

To set the t-out timer in the physical connection management (PCM), use the fddi t-out interface configuration command. Use the no form of this command to revert to the default value.

fddi t-out milliseconds
no fddi t-out

Syntax Description

milliseconds

Number that sets the timeout timer. The default is 100 milliseconds.

Default

100 milliseconds

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

This command applies to the processor 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.

Example

The following example sets the timeout timer to 200 milliseconds:

interface fddi 0
  fddi t-out 200

Related Commands

You can use the master indexes or search online to find documentation of related commands.

fddi c-min
fddi tb-min
fddi tl-min-time

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 interface configuration command.

fddi token-rotation-time microseconds

Syntax Description

microseconds

Number that specifies the token rotation time (TRT). The default is 5,000 microseconds.

Default

5000 microseconds

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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:

interface fddi 0
  fddi token-rotation-time 24000

The following example sets the rotation time to 24,000 microseconds on a Cisco 7500 series router:

interface fddi 3/0
  fddi token-rotation-time 24000

fddi valid-transmission-time

To recover from a transient ring error, use the fddi valid-transmission-time interface configuration command.

fddi valid-transmission-time microseconds

Syntax Description

microseconds

Number that specifies the transmission valid timer (TVX) interval. The default is 2,500 microseconds.

Default

2,500 microseconds

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

Examples

The following example changes the transmission timer interval to 3000 microseconds:

interface fddi 0
  fddi valid-transmission-time 3000

The following example changes the transmission timer interval to 3000 microseconds on a Cisco  7000 series routers or Cisco  7200 series routers:

interface fddi 3/0
  fddi valid-transmission-time 3000

fdl

To set the facilities data link exchange standard for the CSU controllers, enter the fdl controller configuration command. Use the no form of this command, to disables facilities data-link support.

fdl {att | ansi | both}
no fdl {att | ansi | both}

Syntax Description

att

Selects AT&T technical reference 54016 for extended superframe facilities data link exchange support.

ansi

Selects ANSI T1.403 for extended superframe facilities data link exchange support.

both

(Supported on the Cisco MC3810 only) Specifies to support both AT&T technical reference 54016 and ANSI T1.403 for extended superframe facilities data link excchange support.

Default

Disabled

Command Mode

Controller configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.3.

This command was modified in Cisco IOS Release 12.0, to add command syntax both for the MC3810.

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.

Example

The following example configures the ANSI T1.403 standard for both T1 controllers:

Router(config)# controller t1 0
Router(config-controller)# fdl ansi
Router(config-controller)# exit
Router(config)# controller t1 1
Router(config-controller)# fdl ansi

framing (E1/T1 controller)

Use the framing controller configuration command to select the frame type for the E1 or T1 data line.

framing {sf | esf} (for T1 lines)
framing {crc4 | no-crc4} [australia] (for E1 lines)

Syntax Description

sf

Specifies super frame as the T1 frame type.

esf

Specifies extended super frame as the T1 frame type.

crc4

Specifies CRC4 frame as the E1 frame type.

no-crc4

Specifies no CRC4 frame as the E1 frame type.

australia

(Optional) Specifies the E1 frame type used in Australia.

Defaults

Super frame is the default on a T1 line.

CRC4 frame is the default on an E1 line.

Command Mode

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 line. The service provider determines which framing type, either sf, esf, or crc4, is required for your T1/E1 circuit.

Example

The following example selects extended super frame as the T1 frame type:

framing esf

Related Commands

You can use the master indexes or search online to find documentation of related commands.

cablelength
linecode

framing (E3/T3 interface)

To specify E3 or T3 line framing for a PA-E3 port adapter or PA-T3 port adapter, use the framing interface configuration command. To return to the default G.751 framing or C-bit framing, use the no form of this command.

framing {bypass | g751} (PA-E3)
framing {c-bit | m13 | bypass} (PA-T3)
no framing

Syntax Description

bypass

Specifies bypass E3 framing.

g751

Specifies G.751 E3 framing. This is the default for the PA-E3.

c-bit

Specifies that the C-bit framing is used as the T3 framing type. This is the default for the PA-T3.

m13

Specifies m13 T3 framing.

Default

G.751 framing for PA-E3

C-bit framing for PA-T3

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.1 CA.

The default framing is described in the ITU-T Recommendation G.751.


Note The ITU-T carries out the functions of the former Consultative Committee for International Telegraph and Telephone (CCITT).

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 option, 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 controller serial EXEC command.

Example

The following example sets the framing mode to bypass on interface 1/0/0:

interface serial 1/0/0
  framing bypass

Related Command

You can use the master indexes or search online to find documentation of related commands.

show controllers serial

framing (T3 controller)

To specify T3 line framing used by the CT3IP port adapter, use the framing controller configuration command. Use the no form of this command to restore the default framing type.

framing {c-bit | m23 | auto-detect}
no framing

Syntax Description

c-bit

Specifies that the C-bit framing is used as the T3 framing type.

m23

Specifies that the M23 framing is used as the T3 framing type.

auto-detect

Specifies that the CT3IP detects the framing type it receives from the far-end equipment. This is the default.

Default

auto-detect for CT3IP

Command Mode

Controller configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.1 CA.

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.

Example

The following example sets the framing for the CT3IP to C-bit:

controller t3 9/0/0
  framing c-bit

Related Commands

You can use the master indexes or search online to find documentation of related commands.

t1 framing

full-duplex

To specify full-duplex mode on full-duplex single-mode and multimode port adapters, use the full-duplex interface configuration command. Use the no form of this command to restore the default half-duplex mode.

full-duplex
no full-duplex

Syntax Description

This command has no arguments or keywords.

Default

Half-duplex mode is the default mode on a Cisco 7500 series router and a FEIP.

Half-duplex mode is the default mode for serial interfaces that are configured for bisynchronous tunneling.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.1.

This command was modified in Cisco IOS Release 11.3 to include information on FDDI full-duplex, single-mode and multimode port adapters.

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 routers:

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 For the Cisco AS5300, the duplex {full | half | auto} command syntax replaces the full-duplex and half-duplex commands.You will get the following error messages if you try to use the full-duplex and half-duplex command on a Cisco AS5300:
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:

interface fastethernet 0/1
 full-duplex

The following example specifies full-duplex binary synchronous communications (BSC) mode:

interface serial 0
  encapsulation bstun
  full-duplex

The following example enables full-duplex mode on FDDI interface 0:

interface fddi 0/1/0
  full-duplex

Related Commands

You can use the master indexes or search online to find documentation of related commands.

half-duplex
interface fastethernet
interface fddi
interface serial

half-duplex

Use the half-duplex interface configuration command to specify 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. Refer to the Cisco Product Catalog for specific model numbers of port adapters.

Use the no form of this command to reset the interface for full-duplex mode.

half-duplex
no half-duplex

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.1.

This command was modified in Cisco IOS Release 11.3 to include information on FDDI full-duplex, single-mode and multimode port adapters.


Note The half-duplex command replaces both the sdlc hdx and media-type half-duplex commands.
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.

Caution For the Cisco AS5300, the duplex {full | half | auto} command syntax replaces the full-duplex and half-duplex commands.You will get the following error messages if you try to use the full-duplex and half-duplex command on a Cisco AS5300:
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

Enable Full-Duplex Mode

To enable full-duplex mode, use the no half-duplex or full-duplex commands.


Note The media-type half-duplex command exists in Cisco IOS Release 11.0(5). As of Release  11.0(6), the keyword half-duplex was removed from the media-type command. In Release  11.0(6), the functionality for specifying half-duplex mode is provided by the half-duplex command.

Example

The following example configures an SDLC interface for half-duplex mode:

encapsulation sdlc-primary
half-duplex

Related Commands

You can use the master indexes or search online to find documentation of related commands.

full-duplex

half-duplex controlled-carrier

Use the half-duplex controlled-carrier interface configuration command to place a low-speed serial interface in controlled-carrier mode, instead of constant-carrier mode. Use the no form of this command to return the interface to constant-carrier mode.

half-duplex controlled-carrier
no half-duplex controlled-carrier

Syntax Description

This command has no arguments or keywords.

Default

Constant-carrier mode, where DCD is held constant and asserted by the DCE half-duplex interface.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.2.

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 media-type half-duplex command. These interfaces are available on Cisco 2520 through 2523 routers.

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.

Changing to controlled-carrier mode from the default of constant-carrier operation:

interface serial 2
  half-duplex controlled-carrier

Changing to constant-carrier operation from controlled-carrier mode:

interface serial 2
  no half-duplex controlled-carrier

Related Commands

You can use the master indexes or search online to find documentation of related commands.

half-duplex timer
physical-layer

half-duplex timer

To tune half-duplex timers, use the half-duplex timer interface configuration command. Use the no form of this command, along with the appropriate keyword, to return to the default value for that parameter.

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}

You can configure more than one of these options, but each option must be specified as a separate command.

Syntax Description

cts-delay value

Specifies the delay introduced by the DCE interface between the time it detects RTS to the time it asserts CTS in response. The range is dependent on the serial interface hardware. The default value is 0  milliseconds.

cts-drop-timeout value

Determines the amount of time a DTE interface waits for CTS to be deasserted after it has deasserted RTS. If CTS is not deasserted during this time, an error counter is incremented to note this event. The range is 0  to  1140000  milliseconds (1140 seconds). The default value is 250  milliseconds.

dcd-drop-delay value

Applies to DCE half-duplex interfaces operating in controlled-carrier mode (see the half-duplex controlled-carrier command). This timer determines the delay between the end of transmission by the DCE and the deassertion of DCD. The range is 0  to  4400  milliseconds (4.4  seconds). The default value is 100  milliseconds.

dcd-txstart-delay value

Applies to DCE half-duplex interfaces operating in controlled-carrier mode. This timer determines the time delay between the assertion of DCD and the start of data transmission by the DCE interface. The range is 0  to  1140000 ms (1140  seconds). The default value is 100  milliseconds.

rts-drop-delay value

Specifies the time delay between the end of transmission by the DTE interface and deassertion of RTS. The range is 0  to  1140000  milliseconds (1140  seconds). The default value is 3  milliseconds.

rts-timeout value

Determines the number of milliseconds the DTE waits for CTS to be asserted after the assertion of RTS before giving up on its transmission attempt. If CTS is not asserted in the specified amount of time, an error counter is incremented. The range is dependent on the serial interface hardware. The default value is 3  milliseconds.

transmit-delay value

Specifies the number of milliseconds a half-duplex interface will delay the start of transmission. In the case of a DTE interface, this delay specifies how long the interface waits after something shows up in the transmit queue before asserting RTS. For a DCE interface, this dictates how long the interface waits after data is placed in the transmit queue before starting transmission. If the DCE interface is in controlled-carrier mode, this delay shows up as a delayed assertion of DCD.

This timer enables the transmitter to be adjusted if the receiver is a little slow and is not able to keep up with the transmitter. The range is 0  to  4400  milliseconds (4.4 seconds). The default value is 0  milliseconds.

Default

The default cts-delay value is 0  milliseconds.

The default cts-drop-timeout value is 250  milliseconds.

The default dcd-drop-delay value is 100  milliseconds.

The default dcd-txstart-delay value is 100  milliseconds.

The default rts-drop-delay value is 3  milliseconds.

The default rts-timeout value is 3  milliseconds.

The default transmit-delay value is 0  milliseconds.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.3.

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.


Note The half-duplex timer cts-delay command replaces the sdlc cts-delay command. The half-duplex timer rts-timeout command replaces the sdlc rts-timeout command.
Value Ranges

The range of values for the cts-delay and rts-timeout keywords are dependent on the serial interface hardware.

Example

The following example set the cts-delay timer to 10 ms and the transmit-delay timer to 50  milliseconds:

interface serial 2
  half-duplex timer cts-delay 10
  half-duplex timer transmit-delay 50

Related Commands

You can use the master indexes or search online to find documentation of related commands.

half-duplex controlled-carrier
physical-layer

hold-queue

To specify the hold-queue limit of an interface, use the hold-queue interface configuration command. Use the no form of this command with the appropriate keyword to restore the default values for an interface.

hold-queue length {in | out}
no hold-queue {in | out}

Syntax Description

length

Integer that specifies the maximum number of packets in the queue.

in

Specifies the input queue.

out

Specifies the output queue.

Default

The default input hold-queue limit is 75 packets. The default output hold-queue limit is 40 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 Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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 EXEC command show interfaces.


Note Increasing the hold queue can have detrimental effects on network routing and response times. For protocols that use seq/ack packets to determine round trip times, do not increase the output queue. Dropping packets instead informs hosts to slow down transmissions to match available bandwidth. This is generally better than having duplicate copies of the same packet within the network (which can happen with large hold queues).

Example

The following example sets a small input queue on a slow serial line:

interface serial 0
 hold-queue 30 in

Related Commands

You can use the master indexes or search online to find documentation of related commands.

show interfaces


hssi external-loop-request

Use the hssi external-loop-request interface configuration command to allow the router to support a CSU/DSU that uses the LC signal to request a loopback from the router. Use the no form of this command to disable the feature.

hssi external-loop-request
no hssi external-loop-request

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

The HSA applique (on the 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.


Note If your CSU/DSU does not support this feature, it should not be enabled in the router. Not enabling this feature prevents spurious line noise from accidentally tripping the external loopback request line, which would interrupt the normal data flow.

Example

The following example enables a CSU/DSU to use the LC signal to request a loopback from the  router:

hssi external-loop-request

hssi internal-clock

To convert the HSSI interface into a clock master, use the hssi internal-clock interface configuration command. Use the no form of this command to disable the clock master mode.

hssi internal-clock
no hssi internal-clock

Syntax Description

This command has no arguments or keywords.

Default

Disabled

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.0.

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 HSSI network module provides full-duplex connectivity at Synchronous Optical Network (SONET) OC-1/STS-1 (51.840 Mhz), T3 (44.736 MHz), and E3 (34.368 MHz) rates in conformance with the EIA/TIA-612 and EIA/TIA-613 specifications. The actual rate of the interface depends on the external data service unit (DSU) and the type of service to which it is connected.

Example

The following example converts the HSSI interface into a 45 MHz clock master:

hssi internal-clock 45 MHz

hub

To enable and configure a port on an Ethernet hub of a Cisco 2505 or Cisco 2507, use the hub global configuration command.

hub ethernet number port [end-port]

ethernet

Indicates that the hub is in front of an Ethernet interface.

number

Hub number, starting with 0. Since there is currently only one hub, this number is 0.

port

Port number on the hub. On the Cisco 2505, port numbers range from 1 to 8. On the Cisco 2507, port numbers range from 1 to 16. If a second port number follows, then the first port number indicates the beginning of a port range.

end-port

(Optional) Last port number of a range.

Syntax Description

Default

No hub ports are configured.

Command Mode

Global configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 10.3.

Examples

The following example enables port 1 on hub 0:

hub ethernet 0 1
no shutdown

The following example enables ports 1 through 8 on hub 0:

hub ethernet 0 1 8
no shutdown

Related Commands

You can use the master indexes or search online to find documentation of related commands.

shutdown

ignore-dcd

Use the ignore-dcd interface configuration command to configure the serial interface to monitor the DSR signal (instead of the DCD signal) as the line up/down indicator. Use the no form of this command to restore the default.

ignore-dcd
no ignore-dcd

Syntax Description

This command has no arguments or keywords.

Default

The serial interface, operating in DTE mode, monitors the DCD signal as the line up/down indicator.

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.0.

This command applies to Quad Serial NIM interfaces on the Cisco 4000 series routers and Hitachi-based serial interfaces on the Cisco  2500 and 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 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.

Example

The following example configures serial interface 0 to monitor the DSR signal as the line up/down indicator:

interface serial 0
  ignore-dcd

ignore-hw local-loopback

To disable the monitoring of the LL pin when in DCE mode, enable the ingnore-hw local-loopback interface configuration command. 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.

Default

Enable

Command Mode

Interface configuration

Usage Guidelines

This command first appeared in Cisco IOS Release 11.3.

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 flapping and the loss of SDLLC sessions.


Note This command only works with the low-speed serial interfaces.

Example

The following example displays how to disable the monitoring of the LL pin when in DCE mode:

Router#conf term
Router(config)#interface serial 2


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