SB5101 Cable Modem Overview
MOTOROLA BCS
CONFIDENTIAL
Page 11 of 34
The Cable Modem has three active interfaces, the HFC, the Ethernet and the USB and each
interface has both a MAC and an IP address associated with it. When operating normally it is the
IP address of the HFC interface that is used for diagnostic access to the modem. However the IP
address associated with the Ethernet interface is always available to the client side network,
unless it has been disabled by management command. This means that a PC on the client side
can access the WEB pages within the modem using the reserved address 192.168.100.1. This is
a non-routed address so it cannot be reached from the Internet (routed) side of the network
The SB5100 family of modems contain an internal DHCP server, which is active until the modem
registers with the CMTS. In the case of a problem that prevents the modem from completing its
registration, the modem can still give an IP address to the client PC to enable diagnostics access.
This address is given with a very short lease (around 10 seconds) so that as soon as the
registration does complete the client PC obtains its proper IP address from the core network
DHCP server.
The WEB interface consists of the following pages:
7 WEB Page Diagnostic Tool.
