ADC Telecommunications, Inc.
244 CHAPTER 12: CONFIGURING DHCP RELAY
About DHCP Relay
DHCP is used within a DOCSIS- or EuroDOCSIS-compliant network to
allocate IP addresses and to configure cable modems with other IP
parameters.
DHCP Relay support on DOCSIS or EuroDOCSIS modules enables a cable
interface (CMTS) to forward DHCP Requests from cable modems, CPE
devices, MTA devices, and other IP hosts to a DHCP server. The DHCP server
may reside:
■Externally, on a system other than the Cuda 12000 that has the cable
interface you are configuring.
■Internally, on the same Cuda 12000 that has the cable interface that you
are configuring.
Note: You may configure the CMTS to forward DHCP Requests to up to 32
servers using DHCP Policies. For more information, see “Configuring D HCP
and BOOTP Policies” on page253.
Gateway addresses are used by the DHCP Relay to request a specific subnet
for the host and cable modem.
Configuration is accomplished within interface cable <c/s/i> mode using the
dhcp-relay command. Using this command, you can configure the
following functions:
■Enable or disable DHCP Relay
■Configure the following gateway addresses:
■CPE/IP Host Gateway Address — The Host Gateway address that
the DHCP Relay requests on behalf of the host. This is the same
address as the Gateway Address configured on the interface. When a
DHCP request is received and it is from the host, then the Hos t
Gateway Address is used by the DHCP Relay.
■Cable Modem (CM) Gateway Address — The CM Gateway address
that the DHCP Relay requests on behalf of the cable modem. This is
the same address as the Gateway Address configured on the
interface. When a DHCP Request is received and it is from the cable
modem, then the CM Gateway Address is used by the DHCP Relay.