Installation guide

5-10
Cisco uBR7100 Series Universal Broadband Router Software Configuration Guide
OL-2238-03
Chapter 5 Troubleshooting the System
Managing Cable Modems on the HFC Network
• To enable rate limiting on the given downstream port using the token bucket policing algorithm,
enter 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, enter the cable downstream rate-limit token-bucket shaping
command.
• To enable rate limiting on the given downstream port using the token bucket policing algorithm with
a specific traffic shaping time granularity, enter the
cable downstream rate-limit token-bucket shaping granularity 8 command.
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, enter the cable downstream rate-limit
token-bucket shaping granularity 8 command. Acceptable values are 128, 256, 512, or 1028 msecs.
• To remove rate limiting on the given downstream port, enter the
cable 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, enter the
cable downstream rate-limit weighted-discard 3 command. Acceptable values are 1, 2, 3, or 4.
Configuring Upstream Rate Limiting and Shaping
You can 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.
To configure upstream rate limiting and shaping, use the following command in cable interface
configuration mode.
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
Tip Upstream grant shaping is per CM (SID). Shaping can be enabled or disabled for the token bucket
algorithm.
Command Purpose
CMTS01(config-if)# [no] cable
upstream n1 rate-limit
[token-bucket]
Enables or disables DOCSIS rate limiting or shaping on an
upstream channel. The
n1 argument depends on the number
of upstream channels on the specific cable modem card.