Contents:
Web Diagnostic Interface Reference
Troubleshooting
USRobotics Regulatory Information
Troubleshooting
In the event that a cable modem does not appear to be functioning properly, use the following troubleshooting tips to assist in solving the problem.
CPE Connection
- Ensure the cable modem is properly connected to the CPE via a functioning USB or Ethernet cable and that the cable modem is powered on. The RF cable should NOT be attached.
- Check the IP address of the attached CPE. It should be 192.168.100.3 if it is properly connected to the cable modem.
- PING the cable modem CPE interface at 192.168.100.1 to verify that it is properly connected to the CPE.
- Open a Web browser and attempt to load the Web diagnostic pages from the cable modem at http://192.168.100.1 or http://cablemodem.web. The user ID is "cablemodem" and the password is "robotics."
Downstream
Make sure that the RF cable is securely attached to the coaxial port of the cable modem. You may also want to make sure that the other end of the RF cable is securely attached to the coaxial jack provided for the cable modem's location.
Check the status of the LEDs to determine if the cable modem is scanning for the downstream. During the scanning process, the LEDs of the cable modem will appear like this:
| Legend | |
 |
LED On |
 |
LED Off |
 |
LED Blink |
|
PWR
|
TST
|
PC
|
SD
|
RD
|
CBL
|
RDY
|
|
|
|
|
|
|
|
|
Once the downstream has been determined, and the cable modem has established QAM lock, the LEDS will appear like this:
|
PWR
|
TST
|
PC
|
SD
|
RD
|
CBL
|
RDY
|
|
|
|
|
|
|
|
|
Check the Downstream Status page of the Web diagnostic pages in the cable modem to determine if QAM lock has been achieved.
Upstream ranging will not occur until a downstream signal has been successfully acquired and QAM locked.
- Once the downstream lock has been activated and the modem begins ranging, the LEDS will appear like this:
|
PWR
|
TST
|
PC
|
SD
|
RD
|
CBL
|
RDY
|
|
|
|
|
|
|
|
|
Once the upstream has been fully ranged and the cable modem has registered itself, the LEDs will appear like this:
|
PWR
|
TST
|
PC
|
SD
|
RD
|
CBL
|
RDY
|
|
|
|
|
|
|
|
|
Check the Status page of the Web diagnostic pages in the cable modem to determine if it has properly ranged an upstream channel.
DHCP
Make sure that the cable modem has properly registered with the CMTS. Refer to the Downstream and Upstream pages earlier in this section for troubleshooting tips.
- Check the IP address of the CPE. It should NOT be 192.168.100.3.
- Check the IP address of the cable modem. It should NOT be 192.168.100.1.
- Provided that the MSO has not established an IP Filter that restricts the cable modem from responding to a ping, ping the IP address assigned to the cable modem from the CPE.
TFTP/DOCSIS Configuration
Verify that the cable modem has properly downloaded the DOCSIS configuration file using the Web Diagnostic Interface. This can be determined by checking the Cable Modem Status page or the Operation Configuration page.
In the event that the Transfer Operational Parameters indicator on the Cable Modem Status page of the Web interface does not indicate "DONE," consider the following:
- Does the configuration file shared-secret (md5 key) match the CMTS configuration?
- Does the configuration file enable network access?
- Does the configuration file define at least one class of service?
Use the Web Diagnostic Interface to determine if a DOCSIS configuration file was properly downloaded and processed.
