Cisco Systems uBR7200 Series Configure Traffic Shaping

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Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide

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Chapter4 Troubleshooting the System

Managing Cable Modems on the HFC Network

To verify whether or not the counters in the Station Maintenance List are cleared, enter thefollowing

command. The station maintenance list counter will be 0.

Configure Traffic Shaping

Toconfigure downstreamrate limiting or shape downstream traffic, use the following command in cable

interface configuration mode.

Note Using Cisco IOS Release 12.0(5)T1 or higher, the software adds downstream calendar

queuing routines and grant shaping application of the calendar queues.

Key command usage is elaborated below:

•To enable rate limiting on the given downstream port using the token bucket policing algorithm,

issue the cable downstream rate-limit token-bucket command.

•To enable rate limiting on the given downstream port using the token bucket policing algorithm

with traffic shaping, issue thecable downstream rate-limit token-bucket shaping command.

•To enable rate limiting on the given downstream port using the token bucket policing algorithm

witha specific traffic shaping time granularity,issue the cable downstream rate-limit token-bucket

shaping granularity 8command. Acceptable values are 1, 2, 4, 8, or 16 msecs.

•To enable rate limiting on the given downstream port using the token bucket policing algorithm

with a specific maximum traffic shaping buffering delay, issue thecable downstream rate-limit

token-bucket shaping granularity 8command. Acceptable values are 128, 256, 512, or

1028 msecs.

•To remove rate limiting on the given downstream port, issue thecable downstream rate-limit

token-bucket command.

��To enable rate limiting on the given downstream port using a weighted packet discard policing

algorithm and to assign a weight for the exponential moving average of loss rate value, issue the

cable downstream rate-limit weighted-discard 3command. Acceptable values are 1 to 4.

Youcan rate limit and shape traffic on a DOCSIS upstream channel. This delays the scheduling of the

upstream packet, which in turn causes the packet to be buffered on the cable CPE device, instead of

being dropped. This allows the user’s TCP/IP stack to pace the application traffic appropriately and

approach throughput commensurate with the subscriber’s defined QoS levels.

Table4-11 Instructions to Conﬁgure Downstream Shaping

Command Purpose

CMTS01(config-if)#

[no]

cable downstream rate-limit

token-bucket

[shaping]

weighted-discard

[expwt <n>]

Enables or disables rate limiting and traffic

shaping on the downstream of a cable interface.