Cisco Cisco IOS Software Release 12.2(10) Notas de publicación

This section describes the limitations and restrictions for Cisco IOS DSLAM releases.

The reported DMT aggregate bit rate is less than the true attainable bit rate.

Due to line condition variations between trains, the effect of trellis coding, interleave delay, FEC check 
bytes, and so forth, the attainable bit rate estimate is not always 100 percent accurate. A conservative 
approach was taken in making the estimate; therefore, in general, you can get a higher rate than what the 
estimate suggests. For a fast-path scenario, the results should track fairly closely for the downstream rate 
and err on the conservative side for the upstream rate. For an interleave path scenario, the results are 
highly dependent on configurations.

At a higher reach or where line conditions are not optimal, the effect of having trellis coding, interleave 
delay, and FEC check bytes can provide a much higher rate than was estimated (greater than 128 kbps).

There is no workaround. The aggregate bit rate calculation is an estimate, which does not accurately 
model all of the line conditions that affect the true attainable bit rate for a given profile. The calculations 
for aggregate bit rate are performed as follows:

The downstream capacity is obtained from the number of Reed-Solomon payload bytes per frame 
exchanged during line training, that is, the K value. The per-second estimate is then calculated from 
this K value. An extrapolated margin value is derived from the per-second estimate to make sure that 
if the line is trained at the estimated rate, it will still have an adequate margin.

For upstream, unlike downstream, the Reed-Solomon payload bytes per frame is not readily 
available. Furthermore, unlike downstream, which requires a CPE EOC response to know the 
downstream margin, the upstream margin is readily available at the CO (upstream margin is 

rommon> sync

Sync to save the state of rommon.

rommon> b

When the NI-2 boots, it uses 
ni2-dboot-mz.121-5da.bin as the bootstrap image.

DSLAM# configure terminal

Enter global configuration mode. You have entered 
global configuration mode when the prompt changes to 

DSLAM(config)#

.

DSLAM(config)# config-register value

Set the config-register to the value you recorded in 
Step 5.

DSLAM(config)# exit

Return to enable mode.

Go to the 

“Update the Image in Bootflash to the