Cisco Cisco 6015 IP DSL Switch
2
Cisco IOS Release 12.2(12)DA
Feature Overview
Benefits
G.dmt Support (ITU G.922.1), Annex B/ETSI
G.dmt support is provided through both the Management Information Base (MIB) and the command line
interface (CLI).
interface (CLI).
G.hs Support (ITU G.994.1)
G.hs support is provided through both the MIB and the CLI.
Fast or Interleaved Path Selection
You can configure the parameters for either the fast or interleaved path using the DSL profile
configuration commands. 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 rate 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. After you configure the maximum bit rates for the fast path, the rates for the interleave path must
be zero. Cisco IOS software ensures that only one path is enabled at a given time.
configuration commands. 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 rate 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. After you configure the maximum bit rates for the fast path, the rates for the interleave path must
be zero. Cisco IOS software ensures that only one path is enabled at a given time.
The fast path provides improved latency characteristics for applications that cannot tolerate latency (for
example, voice). Before you migrate from interleaved mode to fast path, determine if the deployed CPEs
offer support for the feature.
example, voice). Before you migrate from interleaved mode to fast path, determine if the deployed CPEs
offer support for the feature.
Trellis Encoding
Trellis encoding improves performance in a noisy environment. It enables you to transmit at faster line rates
with lower error rates, thus providing faster overall throughput in a moderately noisy environment.
with lower error rates, thus providing faster overall throughput in a moderately noisy environment.
By default, the 8xDMT over ISDN line card automatically configures itself for the type of trellis encoding
supported on the CPE. It is no longer necessary to enable trellis encoding in the DSL profile.
supported on the CPE. It is no longer necessary to enable trellis encoding in the DSL profile.
Enhanced Line Quality Monitoring and Management
The 8xDMT over ISDN line card improves the manageability of Discrete Multi-Tone (DMT) ports on
supported DSLAMs. The following commands are used to configure this functionality:
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, a line that trained below the configured minimum bit rate generated a
minor alarm, but the DMT port remained active. The dmt minrate-blocking command prevents
DMT ports from training when bit rates fall below the configured minimum threshold specified in
the dmt bitrate minimum command.
minimum bit rates. Formerly, a line that trained below the configured minimum bit rate generated a
minor alarm, but the DMT port remained active. The dmt minrate-blocking command prevents
DMT ports from training when bit rates fall below the configured minimum threshold specified in
the dmt bitrate minimum command.
Note
If the bit rates on a DMT port violate the minimum allowed bit rates specified in the
dmt bitrate minimum command, the default configuration (DMT minrate-blocking turned off)
generates a minor alarm (if alarms are enabled in the DSL profile).
dmt bitrate minimum command, the default configuration (DMT minrate-blocking turned off)
generates a minor alarm (if alarms are enabled in the DSL profile).
•
dmt rate-adaptation
The dmt rate-adaptation command causes the signal-to-noise ratio (SNR) to be monitored 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.
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.