Table of Contents

Feature Overview

Benefits
Restrictions
Related Features and Technologies
Related Documents

Supported Platforms
Supported Standards, MIBs, and RFCs
Prerequisites
Configuration Tasks

Preprovisioning the 8xDMT Line Card

Verifying the Preprovisioned Slot

Creating and Associating a DSL Profile with Each Port

Verifying the DSL Profiles

Modifying the DSL Profile
Troubleshooting Tips

Monitoring and Maintaining the 8xDMT Line Card
Configuration Examples
Command Reference
alarms
dmt bitrate
dmt check-bytes
dmt margin
dmt minrate-blocking
dmt overhead-framing
dmt rate-adaptation enable
dmt rate-adaptation interval
dmt rate-adaptation margin
slot
Glossary
A
C
D
F
G
H
I
L
M
N
P
R
S
T
U
V

Octal-Port DMT ATU-C Line Card

This feature module describes the Cisco IOS support for the octal-port DMT ATU-C (8xDMT) line card. It includes information on new and modified commands.

This document includes the following sections:

• Feature Overview

• Supported Platforms

• Supported Standards, MIBs, and RFCs

• Prerequisites

• Configuration Tasks

• Configuration Examples

• Command Reference

• Glossary

Feature Overview

The 8xDMT line card provides higher port density for the Cisco 6015, Cisco 6160, and Cisco 6260. This line card:

• Supports eight ADSL modem connections per card.

• Converts ADSL modulation from the line card into digital data streams to and from the NI-2 card.

• Negotiates the line rate with the customer premises equipment (CPE) when it trains and bases the rate on line quality and distance.

• Provides subscriber and port provisioning through DSL profiles.

  • Allows single latency—Fast or interleaved path selection.

  • Supports trellis encoding.

  • Supports bit swapping.

• Interoperates with certain CPE. For more detailed information, see the "Supported Platforms" section.

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  Note   Check with a Cisco customer representative to verify CPE compatibility with the 8xDMT.

  ---

Benefits

G.hs Support (ITU G.994.1)

G.hs support is provided through both the MIB and the CLI. Features from G.hs that are supported include:

• Enabling/disabling all or one of the following modes.

  • G.dmt

  • T1.413 Issue 2

  • G.lite

• Setting auto mode defers the mode selection to the ATU-R.

• Displaying current mode/capability.

Bit Swapping

Bit swapping is a mechanism that allows DMT transceivers to reallocate bits between carriers and adjust gain scaling based on the carrier SNR margin.

Fast or Interleaved Path Selection

The fast path feature allows you to configure either the fast or the interleave path via DSL profile configuration commands provided that the CPE also supports fast path. You can use either the interleave or fast path with the 8xDMT line card provided that the CPE also supports fast path. The fast path provides improved latency characteristics for applications that cannot tolerate latency (for example, voice).

The parameters for either path are configurable using the DSL profile configuration commands. Note that although you can configure both paths, only one path will actually be enabled (dual latency is not supported at this time). Thus the maximum bit rates for the unused path must be zero. For example, to configure and use the fast path, you must specify nonzero maximum bit rates for the fast path. Once you configure the maximum bit rates for the fast path, the rates for the interleave path must be zero. The IOS software ensures that only one path is enabled at a given time.

Trellis Encoding

Trellis encoding is a method of providing better performance in a noisy environment. The end result of using Trellis encoding is that you can transmit at faster line rates with lower error rates, thus providing a faster overall throughput in a moderately noisy environment. You can enable or disable trellis encoding for a specific DSL profile.

Enhanced Line Quality Monitoring and Management

The 8xDMT improves the manageability of DMT ports on supported DSLAMs. The following commands are used to configure this functionality:

• dmt minrate-blocking

DMT minrate-blocking customizes the DMT port reaction to lines that train below configured minimum bit rates. Formerly, if a line trained below the configured minimum bit rate threshold, it would generate a minor alarm, but the DMT port remained active. The dmt minrate-blocking prevents DMT ports from training when bit rates fall below the configured minimum threshold specified in the dmt bitrate minimum command.

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Note   The original option, which generates a minor alarm when configured minimum bit rates are not met, is configured by default in DSL profiles. The default configuration is no dmt minrate-blocking.

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• dmt rate-adaptation

The dmt rate-adaptation command monitors the signal-to-noise ratio (SNR) on DSL lines. When enabled, software monitors the upstream and downstream DMT ports for low SNR margins. When the actual upstream or downstream margin falls below the dmt rate-adaptation margin for the duration of the configured rate-adaptation interval, the line drops and attempts to retrain. If the line is able to retrain, it trains to a lower bit rate with improved SNR margins.

Restrictions

The 8xDMT card is not spectrally compatible with SDSL, G.shdsl, or IDSL. Place these cards in a separate chassis half when using them in the same chassis as 8xDMT line cards.

Related Features and Technologies

The 8xDMT line card is an upgrade of the 4xDMT (6260) and 4xFlexi (6160, 6260, 6015) line cards.

Related Documents

Hardware Documents

A complete list of all DSL hardware product related documentation is available on the World Wide Web at http://www.cisco.com/univercd/cc/td/doc/product/dsl_prod/index.htm.

Software Documents

A complete list of all DSL IOS software product related documentation is available on the World Wide Web at http://www.cisco.com/univercd/cc/td/doc/product/dsl_prod/ios_dsl/index.htm.

In the ATM software product related documentation, look for information pertaining to the Cisco LightStream 1010, which uses the same software base as the NI-2 DSL systems. This documentation is available on the World Wide Web at http://www.cisco.com/univercd/cc/td/doc/product/atm/index.htm.

Supported Platforms

DSLAMs

This feature supports the 8xDMT line card on the Cisco 6015, Cisco 6160, and Cisco 6260 platforms with NI-2. Table 1details the total available ADSL modem connections for each chassis.

Supported Standards, MIBs, and RFCs

Standards

• ANSI T1.413-Issue 2, Category 1 only

• ANSI T1.413-Issue 2, Annex F (Reduced NEXT)

• Universal Test & Operations PHY for ATM, Level 2; A standard for transport of ATM cells over a 16-bit parallel data bus. See ATM Forum document af-phy-0039.000.

• ITU G.992.1, Annex A (G.dmt)

• ITU G.992.2. (G.lite)

• ITU G.994.1. (G.hs)

Standard MIBS

To obtain lists of supported MIBs by platform and Cisco IOS release and to download MIB modules, go to the Cisco MIB web site on Cisco Connection Online (CCO) at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.

• IETF RFC 1695, Definitions of Managed Objects for ATM Management Version 8.0 using SMIv2

• IETF RFC 2662, Definitions of Managed Objects for the ADSL Line (obsoletes ADSL Forum TR- 006, SNMP-based ADSL Line MIB)

  • Objects not supported for 8xDMT:

  From AdslLineConfProfileEntry - adslAtucConfRateChanRatio, adslAtucConfMaxSnrMgn, adslAtucConfUpshiftSnrMgn, adslAturConfRateChanRatio, adslAturConfMaxSnrMgn, adslAturConfUpshiftSnrMgn,adslAturConfMinUpshiftTime.
  

  AdslLineAlarmConfProfileEntry
  

• ADSL Forum TR-014, DMT Line Code Specific MIB

  • Objects not supported for 8xDMT:

  From AdslLineDmtConfProfileEntry- adslAtucDmtConfFreqBins, adslAturDmtConfFreqBins, adslAtucDmtConfInterleavePath, adslAtucDmtConfFastPath, adslAturDmtConfInterleavePath, adslAturDmtConfFastPath.
  

Cisco-Derived MIBS

• CISCO-ADSL-LINE-MIB

  • Objects not supported for DMT8:

• CISCO-ADSL-DMT-LINE-MIB

  • Objects not supported for DMT8:

  From the cAdslDmtLineConfProfileGroup cAdslAtucDmtConfBitSwapEnabled, cAdslAtucDmtConfBitSwapFrom, cAdslAtucDmtConfBitSwapTo. You can set these objects via SNMP, however, the 8xDMT cards will ignore these objects when provisioning ports for service.
  

To obtain lists of supported MIBs by platform and Cisco IOS release and to download MIB modules, go to the Cisco MIB web site on Cisco Connection Online (CCO) at http://www.cisco.com/public/sw-center/netmgmt/cmtk/mibs.shtml.

Prerequisites

To use the 8xDMT feature, you must have one of the following DSLAMs with the 8xDMT line card, and IOS 12.1(6) or above installed:

• Cisco 6015

• Cisco 6160

• Cisco 6260

Configuration Tasks

See the following sections for configuration tasks for the 8xDMT feature. Each task in the list indicates if the task is optional or required.

• Preprovisioning the 8xDMT Line Card (optional)

• Creating and Associating a DSL Profile with Each Port (required)

• Modifying the DSL Profile (optional)

Preprovisioning the 8xDMT Line Card

Starting at the global configuration prompt, use the following commands to preprovision a slot for use with the 8xDMT line card:

Tip After you have completed these steps, insert the 8xDMT line card to activate the card with your preprovisioned configuration.

Verifying the Preprovisioned Slot

Use the show running-configuration command to verify that you preprovisioned the slot correctly.

Creating and Associating a DSL Profile with Each Port

Before starting this configuration task, install the 8xDMT line card. Refer to the Octal-Port DMT ATU-C Line Card FRU Installation and Configuration Notes for information on installing the 8xDMT line card.

Starting at the global configuration prompt, use the following procedure to associate a DSL profile with a port:

Verifying the DSL Profiles

You can use the show dsl profile profile-name command to verify that a DSL profile is attached to a port. You can also use the show running-configuration command to verify that the DSL profile is associated with a port.

Tip If no DSL profile appears in the show running-configuration command output, the default DSL profile is enabled. See the "Command Reference" section for the default configuration values.

Modifying the DSL Profile

Starting at the global configuration prompt, use the following procedure to modify the default bit rate, signal-to-noise ratio, DMT check bytes, and overhead framing parameters in your DSL profile:

Caution   Before migrating from interleave mode to fast path, determine whether the deployed CPEs offer support for the feature. The Cisco 600 series CPEs currently do not support fast path.

Troubleshooting Tips

Cisco provides Cisco.com as a starting point for all technical assistance. Customers and partners can obtain documentation, troubleshooting tips, and sample configurations from online tools.

For Cisco.com registered users, additional troubleshooting tools are available from the TAC website. To obtain troubleshooting help, go to the Cisco Troubleshooting Assistant web site on Cisco Connection Online (CCO) at:

http://www.cisco.com/kobayashi/support/tac/tsa/dslstep.html

Also see the "Monitoring and Maintaining the 8xDMT Line Card" section.

Monitoring and Maintaining the 8xDMT Line Card

Use the following commands to monitor and maintain the 8xDMT line card:

Configuration Examples

The following example shows a profile named 8xDMT2 being created. The profile uses the default profile values for any parameters not specified.

Command Reference

This section documents the new and modified commands that are specific to the8xDMT feature. All other commands used with this feature are documented in the Command Reference for Cisco DSLAMS with NI-2. For information on other Cisco IOS commands that can be used on the NI-2 DSL systems, see the Cisco ATM Switch Router Command Reference Guide.

alarms

To enable alarms in profile command mode, use the alarms command. To disable alarms, use the no form of the command.

Syntax Description

This command has no keywords or arguments.

Defaults

Disabled.

Command Modes

Profile configuration.

Command History

Usage Guidelines

The command affects minor alarms for DSL subscriber ports only. The alarms this command controls apply to these event classes:

• Near End LOS

• Near End interleaved LOCD

• Near End fast LOCD

• Near End LOF

• No CPE detected

• Bit rates below configured minimum

• Subscriber port failure

• Upstream or downstream bit rate not above minimum bit rate

Enabling or disabling alarms affects the specified profile only. For example, if you disable alarms on the default profile, other profiles are unaffected.

Use alarms and no alarms to enable and disable minor alarms related to DSL subscriber ports. When these alarms are disabled, you receive no notification when alarm conditions exist. (Notification methods include console messages, LEDs, the output of the show facility-alarm command, and relay alarm signals to external systems for audible or visible alarms.) However, you can track the condition of DSL ports on which alarms are disabled, including conditions that ordinarily trigger alarms, using the command show dsl interface atm slot#/port#.

You can suppress minimum bit rate alarms without disabling other alarms for the profile.

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Note   The alarms command has no effect on critical alarms, major alarms, or minor alarms related to subsystems other than the DSL subscriber ports.

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Examples

In this example, the command enables alarms for the default profile:

DSLAM# configure terminal DSLAM(config)# dsl-profile default DSLAM(config-dsl-prof)# alarms

Related Commands

Command	Description
dsl-profile profile name	Select an existing DSL profile for modification.
show dsl interface atm slot#/port#	Display DSL, DMT, and ATM status for a port.
show dsl profile	Display a specific profile, all ports to which the profile is currently attached, and those port settings.
show facility-alarm status	Display the current major and minor alarm status, if any, and display the configuration of the alarm thresholds.

dmt bitrate

To set the maximum and minimum allowed bit rates for the fast or interleaved DMT profile parameters, use the dmt bitrate profile configuration command. To reset this command to the default value, use the no form of this command.

Syntax Description

Defaults

• The default no dmt bitrate maximum interleaved sets the maximum downstream and upstream interleaved bit rate to 640 and 128 kbps respectively. This command causes the port to retrain.

• The default no dmt bitrate maximum fast sets both the maximum downstream and upstream fastpath bit rates to zero. This command causes the port to retrain.

• The default no dmt bitrate minimum interleaved sets both the minimum downstream and upstream interleaved bit rates to zero. This command does not cause the port to retrain.

• The default no dmt bitrate minimum fast sets both the minimum downstream and upstream fastpath bit rates to zero. This command does not cause the port to retrain.

Command Modes

Profile configuration.

Command History

Usage Guidelines

Only the alarm subsystem uses the minimum bit rate settings. Cisco IOS asserts an alarm if the line card trains at a rate below the configured minimum bit rate. However, no alarm occurs when you disable alarms. See alarms in the Command Reference for Cisco DSLAMS with NI-2, for more information on enabling and disabling alarms.

Table 2 lists the allowable DMT bit rate ranges and default values.

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Caution   This command causes the port to retrain when you change the value of the bit rate parameter.

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Setting a parameter to its current value does not cause a retrain. If a port is training when you change the parameter, the port stops training and retrains to the new parameter.

Examples

In this example, the command sets the maximum interleaved bit rate of the default profile to 3200 kbps downstream and 640 kbps upstream:

DSLAM# configure terminal DSLAM(config)# dsl-profile default DSLAM(config-dsl-prof)# dmt bitrate maximum interleaved downstream 3200 upstream 640

Related Commands

Command	Description
show dsl profile	Display a specific profile, all ports to which the profile is currently attached, and those port settings.

dmt check-bytes

To set upstream and downstream FEC check (redundancy) bytes, use the dmt-checkbytes profile configuration command. To reset this command to the default value, use the no form of this command.

Syntax Description

Defaults

Downstream: 16

Upstream: 16

Command Modes

Profile configuration.

Command History

Usage Guidelines

Caution   This command causes the port to retrain when you change the check-bytes parameter.

Setting a parameter to its current value does not cause a retrain. If a port is training when you change the parameter, the port untrains and retrains to the new parameter.

Conditions on the line, the configured bit rate, and the capabilities of the ATU-R CPE affect the achievable value for this parameter. As a result, the check-bytes value to which the line trains may be smaller than the value you configure. If you want to use more check bytes than the system is allowing you, use the dmt bitrate command to reduce the bit rate.

Use the command show dsl interface atm slot#/port# to display the configured and actual check-bytes values for the connection.

Examples

In this example, the command sets the interleaved FEC check-bytes for the default profile to 12 downstream and 6 upstream.

Related Commands

None.

dmt margin

To set upstream and downstream signal-to-noise ratio (SNR) margins for a DMT profile, use the dmt margin command. To reset this command to the default value, use the no form of this command.

Syntax Description

Defaults

Downstream: 6 dB

Upstream: 6 dB

Command Modes

Profile configuration.

Command History

Usage Guidelines

Caution   This command causes the port to retrain when you change the parameter.

Setting a parameter to its current value does not cause a retrain. If a port is training when you change this value, the port untrains and retrains to the new value.

Examples

In this example, the command sets the SNR margins of the default profile to 12 dB downstream and 6 dB upstream:

Related Commands

None.

dmt minrate-blocking

To force a port not to retrain when actual bit rates fall below the values configured in the dmt bitrate minimum command, use the dmt minrate-blocking command. To disable dmt minrate-blocking, use the no form of the command.

Syntax Description

This command has no arguments or keywords.

Defaults

The default configuration, no dmt minrate-blocking, generates a minor alarm when the bit rates on a DMT port violate the minimum allowed bit rates specified in the dmt bitrate minimum command (if alarms are enabled in the DSL profile).

Command Modes

DSL profile configuration.

Command History

Usage Guidelines

To specify the bit rate below which a DMT port will not retrain, use the dmt bitrate minimum command.

Examples

The following example describes how to enable dmt minrate-blocking:

dmt overhead-framing

To set the overhead framing mode, use the dmt overhead-framing command.To reset this command to the default value, use the no form of this command.

dmt overhead-framing {mode0 | mode1 | mode2 | mode3}

Syntax Description

mode0	Full overhead framing with asynchronous bit-to-modem timing.
mode1	Full overhead framing with synchronous bit-to-modem timing.
mode2	Reduced overhead framing with separate fast and sync bytes in the fast and interleaved latency buffers respectively.
mode3	Reduced overhead framing with merged fast and sync bytes, using either the fast or interleaved latency buffer.

Defaults

Mode3.

Command Modes

Profile configuration.

Command History

Release	Modification
12.0(5)DA	This command was introduced.
12.1(6)DA	Mode 0 was added.

Usage Guidelines

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Note   Conditions on the line and the capabilities of the ATU-R CPE affect the achievable value for this parameter. As a result, the overhead framing value to which the line trains may not be the same as the value you configure.

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There are two types of ADSL framing:

• Full overhead

• Reduced overhead

There are also two versions of full overhead:

• Asynchronous

• Synchronous

You select the type of ADSL framing by choosing one of four modes:

• Mode 0—Full overhead framing with asynchronous bit-to-modem timing (an enabled synchronization control mechanism).

• Mode 1—Full overhead framing with synchronous bit-to-modem timing (a disabled synchronization control mechanism).

• Mode 2—Reduced overhead framing with separate fast and sync bytes in the fast and interleaved latency buffers respectively.

• Mode 3—Reduced overhead framing with merged fast and sync bytes using either the fast or interleaved latency buffer.

  ---

  Note   Mode 3 is recommended for use on DMT interfaces adhering to the ANSI T1.413 Issue 2 standard. Mode 3 is required for flexi line card DMT interfaces.

  ---

The number of overhead bytes per frame varies according to the overhead framing mode and the operating mode, as shown in Table 3.

dmt rate-adaptation enable

DMT rate adaptation monitors upstream and downstream DMT ports for signal-to-noise ratio (SNR) margins during specified time intervals. If an unacceptable SNR margin is detected, the port is retrained at a lower bit rate to improve the SNR margins. To enable rate adaptation on a DMT port, use the dmt rate-adaptation enable command at the DSL profile configuration prompt. To disable dmt rate adaptation, use the no form of the command.

This command has no arguments or keywords.

Defaults

Enabling dmt rate-adaptation configures the commands dmt rate-adaptation interval and dmt rate-adaptation margin with their default values. For information on the default values of dmt rate-adaptation interval and dmt rate-adaptation margin see the "dmt rate-adaptation interval" section and the "dmt rate-adaptation margin" section.

Command Modes

DSL profile configuration

Command History

Usage Guidelines

If you wish to modify the default configuration of the dmt rate-adaptation interval and dmt rate-adaptation margin see the "dmt rate-adaptation interval" section and the "dmt rate-adaptation margin" section.

Examples

The following example enables dmt rate-adaptation with default interval and margin values:

Related Commands

dmt rate-adaptation interval

To change the intervals during which a DMT port is monitored for signal-to-noise ratio (SNR) margins, use the dmt rate adaptation interval command in DSL profile configuration mode. To disable dmt rate adaptation interval, use the no form of this command.

Syntax Description

Defaults

Following are the default settings for the dmt rate adaptation interval:

• downstream—10

  ---

  Note   Remember, a downstream value of 10 can yield a monitoring interval between 1 minute to 2.5 minutes in length.

  ---

• upstream—10

Command Modes

DSL profile configuration

Command History

Usage Guidelines

Use the dmt rate-adaptation interval to specify the frequency at which line margins are checked on a DMT port. The dmt rate-adaptation interval command works in conjunction with the dmt rate-adaptation margin command. If the actual SNR margins on a port remain lower than the margins configured in the dmt rate-adaptation margin command, for the duration of time specified in the dmt rate-adaptation interval command, the line drops and retrains to a lower bit rate, to improve SNR margin quality on the line.

Note   If line conditions improve, the line does not automatically drop and retrain to a higher bit rate. If the line conditions improve, the administrator must execute a shut then a no shut on the port to retrain to a higher bit rate.

Examples

The following example configures a downstream monitoring interval of roughly 60 to 150 seconds. The upstream monitoring interval is 20 seconds.

Related Commands

dmt rate-adaptation margin

To configure the minimum acceptable SNR margins on a DMT port, which force the port to retrain when bad margins exist for the duration of the dmt rate-adaptation interval, use the dmt rate adaptation margin command in DSL profile configuration mode. To disable dmt rate adaptation margin use the no form of this command.

Syntax Description

Defaults

The default configuration is derived from the no dmt rate-adaptation enable command. This specifies minimum upstream and downstream SNR margins of 0 dB.

Command Modes

DSL profile configuration

Command History

Usage Guidelines

Use the dmt rate-adaptation margin command to configure the acceptable SNR margin thresholds on a specified port. The dmt rate-adaptation margin command works in conjunction with the dmt rate-adaptation interval command. If the actual SNR margins on a port remain lower than the margins configured in the dmt rate-adaptation margin command, for the duration of time specified in the dmt rate-adaptation interval command, the line drops and retrains to a lower bit rate, to improve SNR margin quality on the line.

Note   If line conditions improve, the line does not automatically drop and retrain to a higher bit rate. If the line conditions improve, the administrator must execute a shut then a no shut on the affected port to retrain to a higher bit rate.

slot

To provision a slot for a specific card type, or to change the line coding for a flexi line card, use the slot command.

The 8xDMT line card is spectrally incompatible with both the 8-port IDSL line card and the 4-port SDSL (STU-C) line card. If you install spectrally incompatible cards in the same chassis, the lines served by those cards can suffer reduced performance. For best performance in a chassis with a mixture of line card types, always install 8xDMT line cards on one side of the chassis and install IDSL and SDSL cards on the opposite side.

Glossary

Posted: Wed Jul 17 08:18:37 PDT 2002
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