8-3
Cisco uBR7200 Series Universal Broadband Router Software Configuration Guide
OL-2239-03
Chapter 8 Troubleshooting the System
Understanding show Command Responses
show cable modem
To display all Data-over-Cable Service Interface Specification (DOCSIS)
states, and other useful troubleshooting information, such as last received
upstream radio frequency (RF) power level and maximum number of
provisioned customer premises equipment (CPE), use the
show cable modem
command in privileged EXEC mode.
Note
DOCSIS CMs are required to pass through successive states during
registration and provisioning. Using this information, you can isolate
why a CM is offline or unavailable.
The
show cable flap-list
and
show cable modem
commands indicate when the
Cisco uBR7200 series CMTS has detected an unstable return path for a
particular modem and has compensated with a power adjustment. An asterisk
(*) appears in the power-adjustment field for a modem when a power
adjustment has been made; an exclamation point appears when the modem has
reached its maximum power transmit level and cannot increase its power level
any further.
The
show cable modem
command displays a list of options for a single modem
to be specified by entering either the RF CPE device IP address or MAC
address:
•
Signal-to-noise ratio (SNR) information for each CM on each interface
•
Summary display of the total number of modems connected for each
upstream channel
•
Total number of registered and unregistered modems for the specified
interface or upstream
•
Total number of offline modems for the specified interface or upstream, and
status for each offline modem before it went offline
show cable modem
maintenance
To display station maintenance error statistics, use the
show cable modem maintenance
command in privileged EXEC mode.
When a CM is detected to be offline by the CMTS—no reply after 16 retries of
station maintenance requests—the CM is marked offline. Besides marking the
CM and service identifier (SID) state offline, the SID is removed immediately
from the CMTS ranging list, and an aging timer is started to clean up the SID
completely if the CM does not attempt to come online within the next 24 hours.
Output fields are described below:
•
The
SM Exhausted Count
value refers to the number of times a CM was
dropped because it did not reply to station maintenance requests. A CM is
removed from the station maintenance list after 16 times of periodic
ranging opportunity without seeing the RNG_REQ from the modem.
•
The
SM Aborted Count
value refers to the number of times the CM was
dropped because its operational parameters were unacceptable. This
includes such reasons as the power level is outside the acceptable range, or
the timing offset keeps changing. The respective times in the command
output indicate when this happened.
Command
Purpose
