Cisco Systems UBR924 manual Benefits, Restrictions

Troubleshooting Tips for the

Cisco uBR924 Cable Access Router

Feature Summary

This document describes the Cisco IOS troubleshooting commands that may be used by cable service providers to verify communication between a Cisco uBR924 cable access router and other peripheral devices installed in the HFC headend such as a Cisco uBR7200 series universal broadband router, a DHCP server, and a TFTP server.

Benefits

The Cisco uBR924 cable access router troubleshooting system provides the following benefits:

•A MAC-layer system log file that provides a snapshot of detailed reasons why an interface might reset, along with all the negotiations that occurred between the Cisco uBR924 cable access router and the CMTS. Over 220 possible description fields exist in this log, which is displayed using the show controllers cable-modem 0 mac log command from privileged EXEC mode.

•Debug does not need to be turned on in order to troubleshoot a Cisco uBR924 cable access router.

•The progression of normal data-over-cable communication events is clearly explained, simplifying the resolution of faulty system connections.

•Troubleshooting and diagnostic tasks can be performed on the Cisco uBR924 from a remote location using TELNET.

Restrictions

When using the Cisco uBR924 cable access router, keep the following restrictions and limitations in mind:

•The Cisco uBR924 is able to implement multiple classes of service (CoS) on the cable interface; however, separate CoS streams are only available when the cable access router is connected to a headend that supports multiple CoS per cable access router. In addition, the configuration file downloaded to the cable access router must specify the use of multiple classes of service.

•If the Cisco uBR924 cable access router is connected to a DOCSIS 1.0 headend that does not support multiple CoS per cable access router, voice and data will be mixed, and voice traffic will be transmitted on a best effort basis. This may cause poorer voice quality and lower data throughput when calls are being made from the cable access router’s telephone ports. Voice quality may also be affected when transmitting or downloading large files, or at other times when network traffic is heavy.

Troubleshooting Tips for the Cisco uBR924 Cable Access Router 1