Configuring Headend Broadband Access Router Features
Configuring Cable Profiles
MC-581
Cisco IOS Multiservice Applications Configuration Guide
The following modulation profile values can be changed:
• Interval usage code (iuc)—Valid values are initial, long, reqdata, request, short, and station.
• Fec-tbytes—The number of bytes that can be corrected per FEC codeword. Valid range is
0 to 10 bytes, where 0 means no FEC.
• Fec-len—FEC codeword length. Valid range is 8 to 254 bits.
• Burst-len—Maximum burst length in bytes. A value of 0 means no limit on burst length.
• Guard-t—Guard time in symbols. This is the time between successive bursts.
• Mod—Modulation. Valid values are 16qam and qpsk.
• Scrambler—Enable or disable scrambler. Valid values are scrambler and no-scrambler.
• Seed—Scrambler seed in hexadecimal format. Valid range is 0x0000 to 0x7FFF.
• Diff—Enable or disable differential encoding. Valid values are diff and no-diff.
• Pre-len—Preamble length in bits. Valid range is 2 to 128 bits.
• Last-cw—Handling of FEC for last codeword. Valid values are fixed for fixed codeword length, and
shortened for shortened last code word.
• Uw-len—Upstream unique word length. Enter uw8 for 8-bit unique words or uw16 for 16-bit unique
code words.
To create or change a cable modulation profile, use the following command in global configuration
mode:
In the following example, the request burst for cable modulation profile 2 is defined to have 0 fec-tbytes,
16 KB fec-len, a burst-len of 1, a guard time of 8, a mod value of qpsk, scrambler enabled with a seed
value of 152, differential encoding disabled, a preamble length of 64 bits, a fixed code-word length, and
8-bit unique words for upstream unique word length.
CMTS01(config)# cable modulation-profile 2 request 0 16 1 8 qpsk scrambler 152 no-diff 64
fixed uw8
To remove a cable modulation profile, use the no cable modulation-profile profile command in global
configuration mode. You can use this command to remove all modulation profiles except for modulation
profile 1. Entering the no cable modulation-profile 1 command sets all of the parameters in profile 1
to the default values.
Command Purpose
CMTS01(config)# cable modulation-profile profile iuc
fec-tbytes fec-len burst-len guard-t mod scrambler seed
diff pre-len last-cw uw-len
Creates a new cable modulation profile with a profile
number of
profile, or modifies the existing profile having
the number
profile.
