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To enable upstream or downstream baud (symbol) rates, use the cap baud command in profile configuration mode. Use the no form of the command to disable a previously set baud rate.
cap baud {downstream cap-baudrate | upstream cap-baudrate}
downstream cap-baudrate | Enable a downstream baud rate. The valid value is 136K. |
upstream cap-baudrate | Enable an upstream baud rate. The valid values are 17K and 68K. |
Downstream: 136 kbaud is enabled
Upstream: 68 kbaud and 17 kbaud are disabled
The following baud rates are always enabled and cannot be disabled:
Downstream: 340 kbaud, 680 kbaud, 952 kbaud
Upstream: 136 kbaud
Profile configuration
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Baud rates affect bit rates. Enabling more baud rates causes more bit rates to become available on the affected lines (see cap bitrate). However, the baud rates legally available to you may be determined by tariffs. Consult your organization's legal department before setting the baud rate.
The baud rate settings are mutually independent; you can enable or disable any baud rate without affecting the others. If you disable all configurable baud rates, the affected interfaces will still be able to pass data because there are unconfigurable baud rates that you cannot disable (see the "Defaults" section).
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Note The 17k and 68k upstream baud rates are not available on the dual-port CAP line card. Use the upstream keyword with the Flexi card only. |
The commands in this example disable the 136 kbaud rate downstream and enable the 68 kbaud rate upstream for the profile named issis:
DSLAM# configure terminal DSLAM(config)# dsl-profile issis DSLAM(config-dsl-prof)# no cap baud downstream 136k DSLAM(config-dsl-prof)# cap baud upstream 68k DSLAM(config-dsl-prof)# end
To set the downstream and upstream minimum or maximum bit rates, use the profile configuration command cap bitrate. Use the no form of the command to set bit rates to default values.
cap bitrate minimum downstream min-cap-bitrate upstream min-cap-bitrate
min-cap-bitrate | If the line trains below this rate, the system generates an alarm. See the "Usage Guidelines" below for available values and for more information on alarms. |
max-cap-bitrate | The rate at which the line attempts to train. If the line cannot train at the configured maximum rate, the modems attempt to train at the closest rate possible without exceeding the configured maximum. See the "Usage Guidelines" below for available values. |
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Profile configuration
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Only the alarm subsystem uses the minimum bitrate settings. Cisco IOS asserts an alarm if the line card trains at a rate below the configured minimum bitrate. However, no alarm is generated when alarms are disabled for the profile. See alarms, for more information on enabling and disabling alarms.
Before you use the cap bitrate command, use the cap baud command to enable and disable baud rates. When you use the cap bitrate command, set the maximum bitrates, both downstream and upstream, before you set the minimum bitrates.
It is important to set baud and bit rate parameters in the order specified above because the baud rates that you enable or disable affect the bit rates that are available to you. Also, the maximum bit rates you select affect the minimum bit rates that are available.
Table 2-1 shows bit rate values. In the Valid Values column, values that are always available are shown in bold. Values not shown in bold are not available under certain circumstances:
| Parameter | Direction | Valid Values (kbps)1 | Default Value (kbps) |
|---|---|---|---|
max-cap-bitrate | Downstream | 256, 384, 512, 640, 768, 896, 960, 1024, 1280, 1600, 1920, 2240, 2560, 2688, 3200, 4480, 5120, 6272, 7168 | 640 |
Upstream | 12, 34, 46, 51, 68, 85, 91, 102, 119, 136, 204, 272, 340, 408, 476, 544, 680, 816, 952, 1088 | 91 | |
min-cap-bitrate | Downstream | Minimum: 0 | 0 |
Upstream | Minimum: 0 | 0 |
| 1Values printed in bold are always available. |
The commands in this example set the maximum downstream and upstream bitrates to 7168 kbps and 1088 kbps respectively:
DSLAM# configure terminal DSLAM(config)# dsl-profile issis DSLAM(config-dsl-prof)# cap bitrate maximum downstream 7168 upstream 1088 DSLAM(config-dsl-prof)# end
The CPE signature indicates the CPE equipment's supported feature set. To set the CPE signature value for each configuration profile, use the cap cpe-signature command in profile configuration mode. Use the no form of the command to set the CPE signature to the default value.
cap cpe-signature cpe-signature
cpe-signature | The range of CPE signature values is 0 to 127. |
The default value is 0 (zero).
Profile configuration
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If the CPE signature value returned by the CPE is less than the value configured on the DSLAM, the two devices do not train. When the CPE signature is set to its default value of 0 on the DSLAM, the feature is disabled; the DSLAM attempts to train with the CPE regardless of the signature value returned by the CPE.
In this example, the command sets the CPE signature to 103 for the DSL profile named issis:
DSLAM# configure terminal DSLAM(config)# dsl-profile issis DSLAM(config-dsl-prof)# cap cpe-signature 103 DSLAM(config-dsl-prof)# end
To set the interleaving delay for a profile, use the cap interleaving-delay command in profile configuration mode. Use the no form of the command to set interleaving delay to the default value.
cap interleaving-delay {short | long | none}
short | Configures a small amount of delay and turns on Reed-Solomon error correction. See the "Usage Guidelines" below for details. |
long | Configures a larger amount of delay and turns on Reed-Solomon error correction. See the "Usage Guidelines" below for details. |
none | Configures no delay and turns off Reed-Solomon error correction. This value is valid only when the downstream baud 136k is enabled, and for bit-rate settings that uses 136K. See the "Usage Guidelines" below for details. Note: If you set interleaving delay to none, the subscriber's line may provide service at a higher bit rate than the one configured. This can happen because setting interleaving delay to none turns off Reed-Solomon error correction, and turning off error correction reduces the overhead on the line, leaving more bandwidth available to the subscriber. |
long
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This command changes the amount of delay by setting interleaving depth. It affects downstream traffic only.
Table 2-2 shows the amount of delay (in milliseconds) that results from various combinations of baud rate, constellation, and interleaving delay settings (short or long), in the downstream direction. Interleaving is not used on upstream traffic.
| Constellation | Short or Long Delay | 136 Kbaud | 340 Kbaud | 680 Kbaud | 952 Kbaud |
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8 | short | 4.4 ms | 4.4 ms | - | - |
long | 49 ms | 49 ms | - | - | |
16 | short | 3.0 ms | 3.0 ms | 3.0 ms | 2.7 ms |
long | 31 ms | 31 ms | 16 ms | 11 ms | |
32 | short | 2.3 ms | 2.3 ms | - | - |
long | 24 ms | 24 ms | - | - | |
64 | short | 1.9 ms | 1.9 ms | 1.8 ms | 1.7 ms |
long | 19 ms | 19 ms | 9.6 ms | 6.8 ms | |
128 | short | 1.6 ms | 1.6 ms | - | - |
long | 16 ms | 16 ms | - | - | |
256 | short | 1.4 ms | 1.4 ms | 1.4 ms | 1.2 ms |
long | 14 ms | 14 ms | 6.8 ms | 5.0 ms | |
256 uncorrected | short | 1.3 ms | 1.3 ms | 1.2 ms | 1.0 ms |
long | 12 ms | 12 ms | 6.0 ms | 4.3 ms |
You can choose the interleaving-delay option none only when 136k downstream baud rate is enabled.
If you configure the interleaving-delay to none but the line card trains at a downstream bit rate that uses a baud rate that is other than 136k, the actual interleaving-delay value the system uses is short.
Table 2-3 lists, in the left column, the downstream maximum bit rates for which the interleaving delay setting none is valid. Because the none setting turns off Reed-Solomon error correction, the actual bit rate on the line will be higher than the configured bit rate, as shown in the right column. The actual bit rate exceeds the configured bit rate because turning off Reed-Solomon error correction reduces the overhead on the line, leaving more bandwidth available to the subscriber.
| Configured Downstream Maximum Bit Rate | Actual Downstream Maximum Bit Rate |
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256 kbps | 272 kbps |
384 kbps | 408 kbps |
512 kbps | 544 kbps |
640 kbps | 680 kbps |
768 kbps | 816 kbps |
896 kbps | 952 kbps |
1024 kbps | 1088 kbps |
In this example, the command sets the interleaving-delay value to none:
DSLAM# configure terminal DSLAM(config)# dsl-profile issis DSLAM(config-dsl-prof)# cap interleaving-delay none DSLAM(config-dsl-prof)# end
To set the upstream and downstream signal-to-noise ratio (SNR) margin values for a CAP profile, use the cap margin command. Use the no form of the command to set the margins to the default values.
cap margin downstream cap-margin upstream cap-margin
cap-margin | Enter the upstream and downstream SNR margins in decibels. The range of values is 0 to 12. |
Downstream: 6 dB
Upstream: 6 dB
Profile configuration
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SNR margin values are in decibels.
In this example, the command sets the SNR margin at 8 dB downstream and 5 dB upstream for the DSL profile issis:
DSLAM# configure terminal DSLAM(config)# dsl-profile issis DSLAM(config-dsl-prof)# cap margin downstream 8 upstream 5 DSLAM(config-dsl-prof)# end
To set the CAP power spectral density mask (PSDM) upstream and downstream values, use the cap psdm command in profile configuration mode. Use the no form of the command to set PSDM to default values.
cap psdm downstream psdm-value upstream psdm-value
psdm-value | Downstream values: -37, -40, -43, -46, -49, -52 Upstream values: -38, -41, -44, -47, -50, -53 |
Downstream: -40 dB
Upstream: -38 dB
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PSDM values are in decibels.
In this example, the command sets the CAP PSDM value to -37 dB downstream and -41 dB upstream:
DSLAM# configure terminal DSLAM(config)# dsl-profile issis DSLAM(config-dsl-prof)# cap psdm downstream -37 upstream -41 DSLAM(config-dsl-prof)# end
Posted: Tue Sep 19 14:27:15 PDT 2000
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