Cisco Systems uBR7200 Activating Upstream Differential Encoding, MC-553, Troubleshooting Tips

Configuring Headend Broadband Access Router Features

Configuring the Upstream Cable Interface

Activating Upstream Differential Encoding

To enable differential encoding on upstream traffic to a specified cable interface, use the following command in cable interface configuration mode:

Command	Purpose
CMTS01(config-if)# cable upstream usport	Enables differential encoding.
differential-encoding

Upstream differential encoding is disabled by default.

Verifying Upstream Differential Encoding

To verify whether or not upstream differential encoding is activated, enter the show running-configcommand and look for the cable interface configuration information. If upstream differential encoding is enabled, a differential encoding entry will be displayed in the show running-configoutput. If upstream differential encoding is disabled, no differential encoding entry will be displayed in the output.

Troubleshooting Tips

To troubleshoot the configuration, perform the following tasks:

•Make sure the cable connections are not loose or disconnected.

•Make sure the Cisco cable modem card is firmly seated in its chassis slot and the captive installation screws are tight.

•Make sure you entered the correct slot and port numbers when you typed the command.

•Make sure you entered the correct upstream port number:

–On the MC16C cable modem card, this can be u0 to u5.

–On the MC14C cable modem card, this can be u0 to u3.

–On the MC12C cable modem card, this can be u0 or u1.

–On the MC11C cable modem card, this can be u0 only.

Activating Upstream Rate Limiting

Upstream rate limiting allows upstream bandwidth requests from rate-exceeding cable modems to be buffered without incurring TCP-related timeouts and retransmits. The CMTS can thus enforce the peak upstream rate for each cable modem without degrading overall TCP performance for the subscriber CPE devices. Upstream grant shaping is per cable modem (SID).

Token bucket policing with shaping is the per-upstream default rate-limiting setting at the CMTS. Shaping can be enabled or disabled for the token bucket algorithm.

Cisco IOS Multiservice Applications Configuration Guide

MC-553