Hello,
can you track down the MAC address of the cable modem ? If you are using a DHCP server, this message could be caused by a security breach, read the explanation below:
´To prevent this type of theft, Cisco Systems has developed a feature that uses the IETF draft standard (5) DHCP LEASEQUERY to validate IP and MAC address pairs. In conjunction with a DHCP server, the Cisco CMTS can determine the MAC address of each cable modem and the IP address each modem was assigned during initialisation. When a modem attempts to connect to the CMTS, the CMTS compares the MAC address and IP address of the modem and if they do not match the DHCP server information, the modem is denied registration. If a user attempts to clone an unassigned IP address the CMTS will be unable to determine a MAC-IP pair and will deny the modem registration´
This is from an article discussing security risks on cable IP networks, here is the link:
COMBATING SECURITY RISKS ON THE CABLE IP NETWORK
http://www.broadcastpapers.com/broadband/IBCCiscoSecurityCableIP02.htm
By the way, here is the explanation from CCO for this error message:
Error Message
%UBR7200-5-UNREGSIDTIMEOUT : CMTS deleted unregistered Cable Modem [enet]
Explanation An unregistered cable modem has been deleted to avoid unaccounted bandwidth usage.
Recommended Action Check the cable modem interface configuration for registration bypass, or check for errors in the TFTP configuration file.
Regards,
GP
