Technical information

ADC Telecommunications, Inc.
434 C
HAPTER 16: 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 “DHCP and BOOTP
Policies” on page 449.
Gateway addresses are used by the DHCP Relay to request a specific subnet
for the host and cable modem. Configuring DHCP Relay involves:
■ Enabling or disabling DHCP Relay
■ Configuring 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 Host
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.
■ MTA Gateway Address — The MTA Gateway address that the DHCP
Relay requests on behalf of the MTA device. This is the same address
as the Gateway Address configured on the interface.When a DHCP