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Parameter
downstream-end-bin
loop-back
bit-swapping
The upstream and downstream start and end bins define the frequency ranges for
upstream and downstream data. The frequency for a particular bin is defined as the
bin number multiplied by 4.3125kHz. You must also make sure to adjust the
max-bitrate and min-bitrate parameters to match the frequency range defined by
the start and end bin numbers. (For information on these parameters, see "Fast and
interleaved bit-rate parameters" on page 7-7.)
You can use the bit rate parameters to adjust the frequency content of the ADSL
signals. For example, splitterless ANSI DMT can be supported by appropriate
adjustment of the frequency range. Splitterless ANSI DMT eliminates the need for
splitters or filters at the subscriber location.
For optimum performance under most conditions, bit swapping can be turned on for
all interfaces. The following example shows how to enable bit swapping for the first
interface of a Stinger MRT:
admin> read al-dmt {1 1 1}
AL-DMT/{ shelf-1 slot-1 1 } read
admin> set line-config bit-swapping = yes
admin> write
Rate-adaptive mode parameters
The rate-adapt-mode-up and rate-adapt-mode-down parameters in the Line-Config
subprofile specify rate-adaptive operations from the subscriber (upstream) or to the
subscriber (downstream). Dynamic rate adaptation is not currently supported, so you
must choose between the values automatic-at-startup (the default) and
operator-controlled.
Automatic-at-startup rate adaptation means that the rate is selected during the training
(startup) process. The line initializes at a minimum specified bit rate and target noise
margin. If the line fails to achieve the minimum bit rate in either direction, it cannot
start, and it sends a message that the requested bit rate was too high. If the line can
support a bit rate that is higher than the minimum and not higher than the
maximum bit rate, it can train up to a higher rate within the acceptable noise margin.
Each direction can have a different minimum and maximum bit rate and use the fast
or interleaved ADSL channel. (Dual latency, which can use both the fast and
interleaved channels in both directions, is not currently supported.)
Operator-controlled rate adaptation means that the line must start at and maintain a
specific planned bit rate with an acceptable target noise margin. If the line fails to
achieve the planned bit rate in either direction, it fails to start, and reports that the
Stinger® MRT Getting Started Guide
Configuring the ADSL Line Interfaces
Setting
Specifies the ending frequency bin for downstream
transmission. The valid range is 32 to 255. The default
value is 255.
Provides a digital or analog loopback on the ADSL
interface when set to digital or analog. No loopback is
present when the default value of none is set.
Used as a noise compensation feature on Annex A
full-rate lines. For optimum performance under most
conditions, set this parameter to yes.
Configuring ATM ADSL-DMT interfaces
7-5
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