Troubleshooting guide

5-8
Cisco Broadband Local Integrated Services Solution Troubleshooting Guide
OL-5169-01
Chapter 5 Troubleshooting DOCSIS Networks
Understanding Initialization States
Configuration File State
The main configuration and administration interface to the MTA is the configuration file downloaded
from the provisioning server. This configuration file contains downstream channel and upstream channel
identification and characteristics, as well as Class of Service settings, Baseline Privacy settings, general
operational settings, network management information, software upgrade fields, filters, and vendor
specific settings.
Common reasons for failure at this state are missing file, wrong file permissions, TFTP server is
unreachable, file is wrong format, file has missing required options, misconfigured required options, or
incorrect options - unknown or invalid TLVs. For a description of the required parameters and guidelines
for their values, see Appendix C of [DOCSIS].
A debug command for configuration file transactions and parsing is:
-> cmAddLogValues (“SEV_ALL FAC_CONFIGFILE”)
Registration State
MAC State --->>> 'registration_state'
After configuration, the modem sends a registration request (REG-REQ) with a required subset of the
configuration settings, as well as the CM and CMTS message integrity checks (MIC). The CM MIC is
a hashed calculation over the configuration file settings which provides a method for the modem to be
sure the configuration file was not tampered with in transit. The CMTS MIC is much the same thing
except it also includes a setting for a shared-secret authentication string. This shared secret is known by
the CMTS and the provisioning server, and ensures that only modems configured by authenticated
provisioning servers will be allowed to register with the CMTS.
Problems with registration state almost always point to a configuration file error. Make sure the modem
and the CMTS both support the settings in the configuration file. Make sure the CMTS allows the
creation of class of service profiles or use a profile created by the CMTS. Check the authentication
strings in the CMTS cable interface configuration and the configuration file.
Establish Privacy State
MAC State --->>> 'establish_privacy_state'
The modem must negotiate baseline privacy with the CMTS through the Baseline Privacy Key
Management protocol, if all of the following are true:
• the modem software supports baseline privacy,
• the class of service is a privacy enabled profile, and
• baseline privacy settings are present in the configuration file.
If errors occur in this state, the likely causes are configuration file misconfigurations. Be certain that
both the CM and the CMTS support baseline privacy and are enabled in the interface configuration for
the CMTS and the configuration file for the CM. Also check Appendix A of [BPKM] for valid option
values.
Another possible error that can be encountered is that due to encryption export restrictions, some vendor
modems may require the following command on the uBR in the interface configuration:
uBR(config-if)# cable privacy 40-bit-des