User guide

4-33
Configuration Guide for Cisco DSLAMs with NI-2
OL-2074-03
Chapter 4 Configuring Digital Subscriber Lines
Setting DSL Profile Parameters
chooses an actual symbols-per-codeword value that is closest (numerically) to the configured symbols
per codeword. Table 4-6 lists the values of symbols per codeword that are allowable for various bit
rate ranges.
When the training mode is set to quick, the modem DSP automatically chooses the codeword size. The one
exception is that if check bytes is set to 0 and the training mode is quick, the codeword size is always 1.
To set the number of symbols per Reed-Solomon codeword, follow these steps:
If you set the codeword size to auto, the number of symbols per codeword depends upon the actual
DMT bit rate. The default codeword size is auto.
This command retrains the port if you change the parameter value. Setting a parameter to its previous
value does not cause a retrain. If a port is training when you change this parameter, the port untrains and
retrains to the new parameter value.
Example
This example sets the number of symbols per Reed-Solomon codeword to 8 upstream and
16 downstream and displays the results:
DSLAM# configure terminal
DSLAM(config)# dsl-profile default
DSLAM(cfg-dsl-profile)# dmt codeword-size downstream 16 upstream 8
DSLAM(cfg-dsl-profile)# end
DSLAM# show dsl profile default
dsl profile default:
Link Traps Enabled: NO
Alarms Enabled: NO
ATM Payload Scrambling: Enabled
Table 4-6 Symbols-per-Codeword Values for Different Bit Rate Ranges
Bit Rate Range (kbps) Symbols per RS Codeword for Auto Symbols per RS Codeword Allowed
8032 to 3616 1 1
3584 to 3168 2 1 or 2
3136 to 1760 2 2
1728 to 1568 4 2 or 4
1536 to 832 4 4
800 to 768 8 4 or 8
736 to 384 8 8
352 to 0 16 16
Command Task
Step 1
DSLAM# configure terminal
Go to the global configuration mode.
Step 2
DSLAM(config)# dsl-profile default
Go to the profile mode.
Step 3
DSLAM(cfg-dsl-profile)# dmt codeword-size
downstream
{symbols | auto} upstream {symbols |
auto
}
Set codeword size. The allowable values for codeword
size (in symbols per RS codeword) are 1, 2, 4, 8, 16,
or auto.
Step 4
DSLAM(cfg-dsl-profile)# end
Exit from profile configuration mode.