Cisco Systems UBR900 specifications Basic Troubleshooting

wait_for_link_up_state.

maintenance_state

Basic Troubleshooting

Figure 6 illustrates the traffic flow during the initialization process.

Figure 6 Cisco uBR900 Series Cable Access Router Provisioning Overview

CMTS Interface	Cisco uBR900 series Cable Access Router
MAP Broadcast	Power on
Contains timesharing info	Establish synch and wait for UCD
Send UCD
	Obtain upstream parameters
	Use temporary SID
	Extract slot info and upstream
	channel to use
	Start ranging

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

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	18195

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.

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 timestamps. This is the most valuable information for troubleshooting the cable interface.

The MAC log file is displayed by entering the show controllers cable-modem 0 mac log command from 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; the normal state when the interface is shut down is

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.

Configuring the Cisco uBR900 Series Cable Access Routers 23