Input Power Levels; Spectrum Management Enhancements In Cisco Ios Release 12.3(9A)Bc; Upstream Traffic Shaping - Cisco 7246VXR - uBR Router Software Configuration Manual

cops tcp window-size

Input Power Levels

The input power level, power-level-dBmV, is an option in the cable spectrum-group command. The
option allows you to specify the expected U.S. input power levels on the upstream receivers on the
CMTS when the cable modems are hopping from one fixed frequency to another or from one band to
another. Each upstream frequency has an associated upstream input power level in dBmV. The power
level is the modem transmit power that each spectrum group can use when an upstream frequency change
is necessary. The input power level may be set at the time of the frequency hop.
Specifying an input power level is done so that the cable modems do not have to increase or decrease
their transmit power with every hop. The cable operator can perform minor power equalizations as a
function of frequency. The valid range is -10 to +10dBmV. The power level value should be changed
only if you want to change the power level as part of spectrum management. Some cable plants may want
to change only the input power level and not the frequency on a daily time schedule.
For information on how to configure input power levels, see the
the

Spectrum Management Enhancements in Cisco IOS Release 12.3(9a)BC

Cisco IOS Release 12.3(9a)BC introduces enhancements to spectrum management for the
Cisco uBR7246VXR router:
•
•
For additional information about CBT 3.2, spectrum management and STM 1.1, refer to the following
documents on Cisco.com:
•
•
•

Upstream Traffic Shaping

This feature allows the cable modem termination system (CMTS) to perform upstream rate shaping on
the DOCSIS (Data-Over-Cable Service Interface Specifications) upstream channel.
With traffic shaping, the CMTS can buffer the grants for rate exceeded modems. This grant buffering at
the CMTS avoids TCP-related timeouts and retransmits resulting in an improved TCP throughput
performance for the rate-exceeded modems. Thus, shaping enables the CMTS to enforce the peak
upstream rate for the modem without degrading overall TCP performance for the modem.
When users do not enable the shaping option for upstream rate limiting, the CMTS upstream-rate-policing
code drops bandwidth requests from CMs that are found to have exceeded their configured-peak-upstream
rate (using different local drop policies). The effect of bandwidth requests (eventually upstream packets)
being dropped causes degraded throughput performance of window-based protocols (like TCP) for these
rate-exceeded modems because of the timeouts and retransmits that follow.
For additional information about upstream traffic shaping, refer to the
Shaping" section on page 3-26
System
Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
1-122
Cisco Cable Modem Termination System Feature Guide
Supports the Cisco Broadband Troubleshooter (CBT) 3.2, page 1-123
Supports Subscriber Traffic Management (STM) Version 1.1, page 1-95
Release Notes for Cisco Broadband Troubleshooter Release 3.2
http://www.cisco.com/en/US/products/sw/netmgtsw/ps530/prod_release_note_chapter09186a0080
293344.html
Spectrum Management for the Cisco CMTS
http://www.cisco.com/en/US/docs/cable/cmts/feature/guide/ufg_spec.html
Subscriber Traffic Management for the Cisco CMTS
https://www.cisco.com/en/US/docs/cable/cmts/feature/ubsubmon.html
on Cisco.com.
and to Spectrum Management for the Cisco Cable Modem Termination
Chapter 1 Overview of Cisco uBR7200 Series Software
"Setting Input Power Level"
on Cisco.com.
(with caveats)
(with caveats)
"Setting Upstream Traffic
section in
OL-2239-05