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Chapter 2
Cisco CMTS Configuration Commands
cable upstream equalization-coefficient
To enable the use of a DOCSIS 1.1 pre-equalization coefficient on an upstream, use the cable upstream
equalization-coefficient command in cable interface configuration mode. To disable the use of the pre-
equalization coefficient, use the no form of this command.
Syntax Description
n
Defaults
Pre-equalization is disabled.
Command Modes
Interface configuration (cable interface only)
Command History
Release
12.2(4)BC1
12.2(15)CX
12.2(15)BC2
Usage Guidelines
The DOCSIS 1.1 specification allows a CM to specify a pre-equalization coefficient so that the CMTS
can engage in adaptive equalization to mitigate the effects of echoes in the cable plant, ingress on the
upstream, in-channel tilt issues, and group delay. This can be needed when the upstream is operating in
16-QAM mode.
The cable upstream equalization-coefficient command enables the use of this adaptive equalization on
an upstream. When pre-equalization is disabled, the Cisco CMTS uses the spectrum adjustments given
in section 4.2, Upstream, of the DOCSIS 1.1 specification.
The CMTS uses an equalization scheme that matches the configuration of the upstream. When the
upstream is configured for DOCSIS 1.0 and DOCSIS 1.1 modulation profiles, the CMTS enables and
uses 8 complex taps. When the upstream is configured for DOCSIS 1.x/2.0 mixed mode, the CMTS uses
24 taps by default, but truncates to 8 taps for DOCSIS 1.x CMs. In DOCSIS 2.0 A-TDMA-only mode,
the CMTS uses 24 taps all the time.
For more information about the use of pre-equalization, see section 6.3, MAC Management Messages,
Note
in the DOCSIS 1.1 specification.
OL-1581-08
cable upstream n equalization-coefficient
no cable upstream n equalization-coefficient
Specifies the upstream port number. Valid values start with 0 for the first
upstream port on the cable interface line card.
Modification
This command was introduced.
Support was added for the Cisco uBR-MC16U/X and Cisco uBR-MC28U/X
cable interface line card, including DOCSIS 2.0 A-TDMA and mixed
modulation profiles.
Support was added for DOCSIS 2.0 A-TDMA and mixed modulation
profiles on the Cisco uBR-MC5X20S/U cable interface line cards.
cable upstream equalization-coefficient
Cisco Broadband Cable Command Reference Guide
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