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Configuring Subscriber-End Broadband Access Router Features
Subscriber-End Broadband Access Router Basic Troubleshooting
MC-632
Cisco IOS Multiservice Applications Configuration Guide
Figure 115 Cisco uBR900 Series Cable Access Router Provisioning Overview
Note For more detail on the provisioning process, see the DOCSIS 1.0 Radio Frequency
Interface (RFI) specification (SP-RFII01-990731 or later revision).
After the Cisco uBR900 series cable access router goes online, it begins transferring data between the
attached CPE devices and the network (Internet, intranet, VoIP). The cable service provider typically
uses DHCP to assign IP addresses to the CPE devices. The number of IP addresses each subscriber can
obtain depends on the services purchased from the provider.
Subscriber-End Broadband Access Router Basic
Troubleshooting
A MAC-layer circular log file is stored inside the Cisco uBR900 series cable access router. This file
contains a history of the log messages such as state event activities and time stamps. This is the most
valuable information for troubleshooting the cable interface.
The MAC log file is displayed when you enter the show controllers cable-modem 0 mac log command
in privileged EXEC mode.
The most useful display fields in this output are the reported state changes. These fields are preceded by
the message
CMAC_LOG_STATE_CHANGE. These fields show how the Cisco uBR900 series progresses
through the various processes involved in establishing communication and registration with the CMTS.
The normal operational state is
maintenance_state ; the normal state when the interface is shut down
is
wait_for_link_up_state.
Note Because the MAC log file holds only a snapshot of 1023 entries at a time, you should try
to display the file within 5 minutes after the reset or problem occurs.
CMTS Interface
Power on
Establish synch and wait for UCD
Obtain upstream parameters
Use temporary SID
Extract slot info and upstream
channel to use
Start ranging
Transmit ranging packet with SID
DHCP request/TFTP boot request
Now in allocated slots
ToD Request
Registration Request
Send QoS Parameters
Now in allocated slots
Cisco uBR900 series online
MAP Broadcast
Contains timesharing info
Send UCD
DHCP Response:
Contains IP addresses
Default gateway, TOD server
TFTP server address
TFTP boot config file name
ToD Response
Registration Response
Contains Assigned SID
Cisco uBR900 series registered
Fail if QoS not available
or authentication failed
Cisco uBR900 series Cable Access Router
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