Cisco Systems uBR7200 manual Verifying Upstream Rate Limiting, MC-554

no cable upstream rate-limit

Configuring Headend Broadband Access Router Features

Configuring the Upstream Cable Interface

To enable upstream rate limiting for an upstream port on a Cisco cable modem card, use one of the following commands in cable interface configuration mode:

	Command	Purpose
Step 1
	CMTS01(config-if)#cable upstream usport rate-limit	Enables rate limiting for the specified upstream cable
	or	interface.
		Enables rate limiting for the upstream cable interface
	CMTS01(config-if)#cable upstream usport rate-limit	employing the token bucket policing algorithm. With
	token-bucket	this command the Cisco uBR7200 series will
	or	automatically drop packets in violation of allowable
		upstream bandwidth.
	CMTS01(config-if)#cable upstream usport rate-limit	Default. Enables rate limiting for the upstream cable
	token-bucket shaping
		interface employing the token bucket policing
		algorithm with traffic shaping.
Step 2
	CMTS01(config-if)# ^Z CMTS01#	Exits to EXEC mode so that you can verify upstream
		rate limiting.

To disable upstream traffic shaping for an upstream port, enter the following command in cable interface configuration mode:

CMTS01(config-if)#no cable upstream usport rate-limit

Verifying Upstream Rate Limiting

To verify whether or not upstream rate limiting has been configured and activated, enter the show running-configcommand and look for the cable interface configuration information. If upstream rate limiting has been configured and enabled, a rate limiting entry will be displayed in the show

running-configoutput. If upstream rate limiting is disabled,will be displayed in the output.

You can also perform the following tasks to verify that rate limiting is enabled on the upstream channel:

Step 1 Configure a low-peak upstream rate limit for the cable modem in its QoS profile. Either use the CLI to modify the QoS profile, or edit the TFTP configuration file.

Step 2 Use a regular rate-limiting algorithm on the upstream without rate shaping and see the drops of the excess bandwidth requests from this cable modem when it exceeds its peak upstream rate.

Use the show interface cx/y sid counters command to see the bandwidth request drops. See that the upstream rate received by that modem is in fact less than its configured peak rate due to the timeouts and backoffs produced by the drop in bandwidth requests. To see the input rate at the CMTS in bps, enter the show interface cx/y sid command.

Step 3 Enable grant shaping on the upstream channel by using the new shaping keyword extension to the token bucket algorithm CLI command.

Cisco IOS Multiservice Applications Configuration Guide

MC-554