Cisco Octal-Port DMT ATU-C Line Card Technical manual

1
Cisco IOS Release 12.1(6)DA
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, page 1
•Supported Platforms, page 4
•Supported Standards, MIBs, and RFCs, page 5
•Prerequisites, page 6
•Configuration Tasks, page 6
•Configuration Examples, page 9
•Command Reference, page 10
•Glossary, page 27
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 on page 4.
Note Check with a Cisco customer representative to verify CPE compatibility with
the 8xDMT.

Octal-Port DMT ATU-C Line Card
Feature Overview
2
Cisco IOS Release 12.1(6)DA
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.

Octal-Port DMT ATU-C Line Card Feature Overview
3
Cisco IOS Release 12.1(6)DA
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.
•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.

Octal-Port DMT ATU-C Line Card
Supported Platforms
4
Cisco IOS Release 12.1(6)DA
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.
The 8xDMT is designed for use with the Cisco 6015, Cisco 6160, or Cisco 6260 chassis in one of the
following configurations:
•Cisco 6015, Cisco 6160, or Cisco 6260 with a POTS splitter chassis—Provisions one modem
directly and is physically connected to one specific subscriber line through the POTS
splitter chassis.
•Cisco 6015, Cisco 6160, or Cisco 6260 without a POTS splitter chassis—Provisions one modem
directly and is physically connected to one specific subscriber line through the main distribution
frame (MDF) connections.
CPE
•Cisco 677
•Cisco 678
•Cisco Soho 77
•Cisco 827
•Cisco IAD 2423
•Cisco 1700, Cisco 2600, and Cisco 3600 series with ADSL WIC
•Alcatel Speed Touch Home
•Alcatel Speed Touch Pro
•Efficient Networks 5260 and 5262
•Westell modems based on Alcatel Microelectronics firmware version 1.4.1
•CPE using ADI chipsets with firmware versions 0X3019BE70 (Version 3.0),
0X2219BE04 (Version 2.2), or 0X2019BE2D (Version 2.0) should operate similar to the Cisco 677
Note A correct firmware version does not guarantee interoperation with third-party CPE. Some
hardware variations can affect performance and error rates. Test the interoperation of CPE
with the 8xDMT in the targeted deployment model before provisioning service.
Table 1 Number of Available Modem Connections for Each Chassis
Chassis Number of Available 8xDMT Slots Total ADSL Modem Connections
Cisco 6015 6 48
Cisco 6160 32 256
Cisco 6260 30 240

Octal-Port DMT ATU-C Line Card Supported Standards, MIBs, and RFCs
5
Cisco IOS Release 12.1(6)DA
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:
FromAdslLineDmtConfProfileEntry- 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.

Octal-Port DMT ATU-C Line Card
Prerequisites
6
Cisco IOS Release 12.1(6)DA
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, page 6 (optional)
•Creating and Associating a DSL Profile with Each Port, page 7 (required)
•Modifying the DSL Profile, page 7 (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:
Tips 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.
Command Purpose
Step 1 DSLAM(config)# slot 1 ATUC-1-DMT8 This command associates the 8xDMT line card with
the specified slot.
Step 2 DSLAM(config)# dsl-profile 8xDMT Creates and names the DSL profile, 8xDMT in
this example.
Step 3 DSLAM(config-dsl-prof)# exit Return to the global configuration prompt.
Step 4 DSLAM(config)# interface atm1/1 Enter interface configuration mode on the port
where you will associate the 8xDMT DSL profile.
Repeat this process on each port that you wish to
associate with a DSL profile.
Step 5 DSLAM(config-if)# dsl profile 8xDMT Associates the DSL profile named 8xDMT with
atm interface 1/1.
Step 6 DSLAM(config-if)# exit Return to the global configuration prompt.

Octal-Port DMT ATU-C Line Card Configuration Tasks
7
Cisco IOS Release 12.1(6)DA
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.
Tips If no DSL profile appears in the show running-configuration command output, the default
DSL profile is enabled. See the “Command Reference” section on page 10 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.
Command Purpose
Step 1 DSLAM(config)# dsl-profile 8xDMT Select the profile that you want to attach to the
selected port. The profile name 8xDMT is used as
an example.
Step 2 DSLAM(config-dsl-prof)# exit Return to the global configuration prompt.
Step 3 DSLAM(config)# interface atm1/1 Enter interface configuration mode on the port
where you will associate the 8xDMT DSL profile.
Repeat this process on each port that you wish to
associate with a DSL profile.
Step 4 DSLAM(config-if)# dsl-profile 8xDMT Associate the DSL profile 8xDMT with
atm interface 1/1.
Step 5 DSLAM(config-if)# exit Return to the global configuration prompt.
Command Purpose
Step 1 DSLAM(config)# dsl-profile 8xDMT Enter DSL profile configuration mode.
Step 2 DSLAM(config-dsl-profile)# dmt bitrate
maximum fast downstream 3200 upstream 640 Set a DMT bit rate of 3200 kbps downstream and 640 kbps
upstream on the fast path. Automatically configures the
interleaved path to 0 kbps.

Octal-Port DMT ATU-C Line Card
Monitoring and Maintaining the 8xDMT Line Card
8
Cisco IOS Release 12.1(6)DA
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 on page 8.
Monitoring and Maintaining the 8xDMT Line Card
Use the following commands to monitor and maintain the 8xDMT line card:
Step 3 DSLAM(config-dsl-profile)# dmt
check-bytes fast downstream 0 upstream 0 Set the upstream and downstream FEC check (redundancy) bytes
to 0.
Step 4 DSLAM(config-dsl-profile)# dmt margin
downstream 12 upstream 6 Set the downstream and upstream signal-to-noise ratio (SNR)
margins for a DSL profile.
Step 5 DSLAM(config-dsl-profile)# dmt
overhead-framing mode1 Set the overhead framing mode, in this example to 1.
Step 6 DSLAM(config-dsl-profile)# exit Return to the global configuration prompt.
Command Purpose
Command Purpose
DSLAM# show dsl interface atm s lot/port
DSLAM# show dsl status DMT
These commands display basic information about the DSL link,
including port status, dsl statistics, line errors, and cards detected.
DSLAM# show facility-alarm status The show facility-alarm status command displays all of the current
major and minor alarms and the user-configurable alarm thresholds
for temperature. After an alarm condition is indicated (by LEDs or
bells), you can use the show facility-alarm status command to
determine the cause of the alarm.
Note You must turn on the alarms in the profile for alarms to
be displayed.
DSLAM# show hardware The show hardware command shows information on each of the
slots in your chassis. It tells whether line cards, fan trays, and PEMs
are present.

Octal-Port DMT ATU-C Line Card Configuration Examples
9
Cisco IOS Release 12.1(6)DA
Configuration Examples
The following example shows a profile named 8xDMT2 being created. The profile uses the default
profile values for any parameters not specified.
Current configuration : 7019 bytes
!
version 12.1
no service pad
service timestamps debug uptime
service timestamps log uptime
no service password-encryption
!
hostname DSLAM
!
boot system flash:ni2-dsl-mz.121-6.DA.bin
slot 1 ATUC-4FLEXIDMT
slot 2 ATUC-1-DMT8
slot 3 ATUC-4FLEXIDMT
slot 4 ATUC-4FLEXIDMT
slot 5 ATUC-4FLEXIDMT
slot 6 ATUC-4FLEXIDMT
enable password cisco
!
!
!
!
!
!
dsl-profile default
dmt bitrate maximum interleaved downstream 8032 upstream 864
cap bitrate maximum downstream 7168 upstream 1088
!
dsl-profile 8xdmt
!
dsl-profile 8xDMT2
dmt overhead-framing mode1
dmt check-bytes fast downstream 12 upstream 6
dmt margin downstream 12 upstream 6
dmt bitrate maximum fast downstream 3200 upstream 640
dmt bitrate maximum interleaved downstream 0 upstream 0
network-clock-select 1 system
ip subnet-zero
ip host-routing
no ip finger

Octal-Port DMT ATU-C Line Card
Command Reference
10
Cisco IOS Release 12.1(6)DA
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.

Octal-Port DMT ATU-C Line Card alarms
11
Cisco IOS Release 12.1(6)DA
alarms
To enable alarms in profile command mode, use the alarms command. To disable alarms, use the no
form of the command.
alarms
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.
Release Modification
12.0(5)DA This command was introduced in a previous release.
12.1(6)DA Conditions that cause alarms were added.

Octal-Port DMT ATU-C Line Card
alarms
12
Cisco IOS Release 12.1(6)DA
Note The alarms command has no effect on critical alarms, major alarms, or minor alarms related to
subsystems other than the DSL subscriber ports.
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.

Octal-Port DMT ATU-C Line Card dmt bitrate
13
Cisco IOS Release 12.1(6)DA
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.
dmt bitrate maximum {fast | interleaved} downstream dmt-bitrate upstream dmt-bitrate
dmt bitrate minimum {fast | interleaved} downstream dmt-bitrate upstream dmt-bitrate
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.
If alarms are enabled for the profile, setting the DMT bit rate to 0 disables the associated minimum DMT
bit rate alarm.
Table 2 lists the allowable DMT bit rate ranges and default values.
dmt-bitrate The DMT bit rate is given as a multiple of 32 kbps. If you enter a
nonmultiple of 32 kbps, the system rejects and aborts the command. See the
allowed ranges and default values in Usage Guidelines.
fast Specify the DMT fast latency path.
interleaved Specify the DMT interleaved latency path.
Release Modification
12.0(5)DA This command was introduced in a previous release.
12.1(5)DA The fast keyword was added.

Octal-Port DMT ATU-C Line Card
dmt bitrate
14
Cisco IOS Release 12.1(6)DA
Caution This command causes the port to retrain when you change the value of the bit rate 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 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
Table 2 Allowable Ranges and Default Values for DMT Bit Rates
Downstream Upstream
Configuration
Parameter Data Path
Aggregate
Range
(kbps)
Path
Range
(kbps)
Path
Default
(kbps)
Aggregate
Range
(kbps)
Path
Range
(kbps)
Path
Default
(kbps)
DMT bit rate max Fast 8064 to 32 8064 to 32 0 864 to 32 864 to 0 0
DMT bit rate min Fast 8064 to 32 8064 to 0 0 864 to 32 864 to 0 0
DMT bit rate max Interleaved 8064 to 32 8064 to 32 640 864 to 32 864 to 0 128
DMT bit rate min Interleaved 8064 to 32 8064 to 0 128 864 to 0 864 to 0 0
Command Description
show dsl profile Display a specific profile, all ports to which the profile is currently attached,
and those port settings.

Octal-Port DMT ATU-C Line Card dmt check-bytes
15
Cisco IOS Release 12.1(6)DA
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.
dmt check-bytes {fast | interleaved} downstream bytes upstream bytes
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.
DSLAM# configure terminal
DSLAM(config)# dsl-profile default
DSLAM(config-dsl-prof)# dmt check-bytes interleaved downstream 12 upstream 6
bytes Enter the upstream and downstream FEC check bytes. The allowed values
are 0, 2, 4, 6, 8, 10, 12, 14, and 16.
fast Specify the DMT fast latency path.
interleaved Specify the DMT interleaved latency path.
Release Modification
12.0(5)DA This command was introduced.
12.1(6)DA The fast keyword was added.

Octal-Port DMT ATU-C Line Card
dmt check-bytes
16
Cisco IOS Release 12.1(6)DA
Related Commands None.

Octal-Port DMT ATU-C Line Card dmt margin
17
Cisco IOS Release 12.1(6)DA
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.
dmt margin downstream dmt-margin upstream dmt-margin
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:
DSLAM# configure terminal
DSLAM(config)# dsl-profile default
DSLAM(config-dsl-prof)# dmt margin downstream 12 upstream 6
Related Commands None.
dmt-margin Enter the upstream and downstream SNR margins in decibels. The range is
0 to 15.
Release Modification
12.0(5)DA This command was introduced.

Octal-Port DMT ATU-C Line Card
dmt minrate-blocking
18
Cisco IOS Release 12.1(6)DA
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.
dmt minrate-blocking
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:
configure terminal
dsl-profile 8xDMT
dmt minrate-blocking
Release Modification
IOS 12.1(6)DA This command was introduced.

Octal-Port DMT ATU-C Line Card dmt overhead-framing
19
Cisco IOS Release 12.1(6)DA
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
Defaults Mode3.
Command Modes Profile configuration.
Command History
Usage Guidelines
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.
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).
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.
Release Modification
12.0(5)DA This command was introduced.
12.1(6)DA Mode 0 was added.

Octal-Port DMT ATU-C Line Card
dmt overhead-framing
20
Cisco IOS Release 12.1(6)DA
•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.
If, during the training sequence, the ATU-R indicates a lower framing structure than that specified by the
ATU-C, the ATU-C falls back to the framing structure number indicated by the ATU-R.
Management requirements drive the determination of overhead, full or reduced. Full overhead provides
more bandwidth to the embedded operations channel (EOC), enabling higher polling rates. However,
reduced overhead provides enough EOC bandwidth to satisfy typical applications.
The dmt overhead-framing command does not cause port retrain when you change the parameter.
Examples In this example, the command sets the overhead framing mode in the profile named 8xDMT.
DSLAM# configure terminal
DSLAM(config)# dsl-profile 8xDMT
DSLAM(config-dsl-prof)# dmt overhead-framing mode2
Related Commands
Table 3 Overhead Bytes per Frame
Framing Mode
Overhead Bytes
T1.413 and G992.1 G992.2
Downstream Upstream Downstream Upstream
Mode 0 4 3 N/A N/A
Mode 1 3 3 N/A N/A
Mode 2 2 2 N/A N/A
Mode 3 1 1 1 1
Command Description
show dsl profile Display a specific profile, all ports to which the profile is currently attached,
and those port settings.