Table of Contents
Advertisement
Chapter 2
Cisco CMTS Configuration Commands
cable upstream maintain-psd
To require DOCSIS 2.0 CMs on an A-TDMA-only upstream to maintain a constant power spectral
density (PSD) after a modulation rate change, use the cable upstream maintain-psd command in cable
interface configuration mode. To return to the default behavior, so that CMs do not need to maintain their
power spectral density, use the no form of this command.
Syntax Description
uport
Defaults
Cable modems are not required to maintain their power spectral density after a modulation rate change
(no cable upstream maintain-psd).
In Cisco IOS Release 12.2(15)BC2 and later releases, this command is automatically removed from the
Note
configuration when you configure an upstream for a TDMA-only or mixed TDMA/A-TDMA
configuration.
Command Modes
Interface configuration (cable interface only)
Command History
Release
12.2(15)CX
12.2(15)BC2
Usage Guidelines
Use this command to specify whether DOCSIS 2.0 CMs should maintain their power spectral density
when the Cisco CMTS changes their upstream modulation rate in an upstream channel descriptor (UCD)
message. When you configure an upstream with the cable upstream maintain-psd command, the
Cisco CMTS sets TLV 15 (Maintain Power Spectral Density) to ON in the UCD messages it sends to the
CMs on that upstream.
When TLV 15 is on, and when the new UCD specifies a new upstream modulation rate for the CM, the
CM must change its transmit power level to keep its power spectral density as close as possible to what
it was before the modulation rate change. The CM must maintain this power spectral density until the
CMTS sends a power adjustment command in a Ranging-Response (RNG-RSP) message.
OL-1581-08
cable upstream uport maintain-psd
no cable upstream uport maintain-psd
Specifies the upstream port to be configured. Upstream port values start
with 0 and end with a value that depends on the number of upstream ports
on the cable interface line card.
Modification
This command was introduced to support DOCSIS 2.0 operations on
the Cisco uBR-MC16U/X and Cisco uBR-MC28U/X cable interface
line card.
Support was added for DOCSIS 2.0 operations on the
Cisco uBR-MC5X20S/U cable interface line cards.
Cisco Broadband Cable Command Reference Guide
cable upstream maintain-psd
2-325
Advertisement
Table of Contents
