Cisco Systems uBR7200 Series manual Blind Strategies and Time Scheduled Combined, Token-bucket

Chapter 4 Troubleshooting the System

Managing Cable Modems on the HFC Network

To configure this, use the following command in cable interface configuration mode.

Table 4-12 Instructions to Configure Upstream Shaping

Command	Purpose
CMTS01(config-if)#[no]cable upstream <n1> rate-limit	Enables or disables DOCSIS rate limiting or
[token-bucket]	shaping on an upstream channel. <n1> depends on
	the number of upstream channels on the specific
	cable modem card.

Using Cisco IOS Release 12.0(5)T1 or higher, the software supports:

•Generic calendar queuing routines

•New token bucket policing function

•Grant shaping application of the calendar queues

•Upstream rate shaping option to the token-bucket keyword

•A default state change from 1 second burst policing to token-bucket with shaping

Tips Upstream grant shaping is per CM (SID). Shaping can be enabled or disabled for the token-bucket algorithm.

Note Before the introduction of this feature, the CMTS would drop bandwidth requests from a CM it detected as exceeding its configured peak upstream rate. Such request dropping affects the throughput performance of IP-based protocols such as FTP, TCP, and SMTP. With this feature, the CMTS can shape (buffer) the grants for a CM that is exceeding its upstream rate, rather than dropping the bandwidth requests.

CMTS01# show interface c3/0 sid 1 counters

Sid	Inpackets	Inoctets	Outpackets Outoctets		Ratelimit	Ratelimit
					BWReqDrop	DSPktDrop
1	67859	99158800	67570	98734862	2579	0

Configure Spectrum Management (without the Cisco MC16S Cable Modem Card)

Blind Strategies and Time Scheduled Combined

The Cisco uBR7200 series software supports combined blind and time scheduled spectrum management using Cisco IOS Release 12.0(5)T1 images or higher:

•Using blind spectrum management, the number of lost station management messages exceeding a configured threshold (default = 10) initiates an upstream channel frequency reassignment. The Cisco uBR7200 series moves all cable modems on the upstream port by sending UCD messages that contain the next frequency and input power level defined in the spectrum management group. The frequency change occurs rapidly without data loss and minimal latency.

Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide

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