Troubleshooting guide

BSR Troubleshooting Guide
4-74
Provisioning Problems Cause CMs Not to Register
It is important to understand the basic communication process between the CM,
cable interface on the BSR, and the DHCP server to troubleshoot provisioning
problems.
The DHCP portion of the CM registration process works as follows:
1. The CM sends a broadcast discovery message to the DHCP server.
2. The DHCP server sends an offer message to the CM that identifies that the
DHCP server is “alive,” and presents connectivity information to the CM.
3. The CM sends a request message to use the information received in the offer
message, and asks for options such as the default gateway, TFTP,
configuraiton file, etc.
4. The DHCP server acknowledges the request, and provisions the CM with an
IP address so that the CM can use TFTP to continue the registration process
and returns options.
Follow these steps to identify CM registration problems associated with
provisioning:
1. To review information about a CM attempting to register with the cable
interface, use the show cable modem command in Privileged EXEC mode, as
shown in the following example:
RDN#show cable modem <MAC address>
2. View the Connectivity State column in the show cable modem command
output.
3. Determine whether the cable interface is receiving a DHCP discover message
from the CM. If the cable interface has received a DHCP discover message
from the CM, a range complete message displays in the connectivity state
column.
4. To show all DHCP traffic traversing the cable interface, use the debug ip udp
dhcp command in Privileged EXEC mode, as shown in the following
example:
RDN#debug ip udp dhcp