Technical information

Cuda 12000 IP Access Switch CudaView Administration Guide
DHCP and BOOTP Policies 447
DHCP and BOOTP Policies
You can use Dynamic Host Configuration Protocol (DHCP) policies to control
which devices obtain IP addresses and which servers allocate those
addresses.
A DOCSIS-compliant network uses DHCP for dynamic assignment of IP
addresses. A DHCP server allocates addresses and other IP operational
parameters to requesting cable modems and CPE devices. DOCSIS and
EuroDOCSIS modules serve as Cable Modem Termination Systems (CMTS)
and, as such, also function as DHCP relay agents. As relay agents, these
cable interfaces relay DHCP requests and responses between the DHCP
server, cable modems, and CPE devices.
DHCP policies allow you to control and restrict the forwarding of DHCP
requests. Specifically, DHCP policies allow matching on several parameters in
the DHCP packet. It then uses the result of this matching to determine which
list of servers to forward the packet to; or it can reject (drop) the packet to
deny the requesting client an address. The relay agent on the CMTS can also
forward Bootstrap Protocol (BOOTP) requests. You can create similar policies
to control the servers to which the interface forwards BOOTP requests.
DHCP and BOOTP policies allow you to:
■ Prevent selected cable modems and CPE devices from obtaining IP
addresses.
■ Direct DHCP requests to particular DHCP servers based on whether the
request originated from a cable modem or CPE device.
■ Direct DHCP requests to particular DHCP servers based on the cable
modem’s or CPE’s MAC address.
■ Direct DHCP requests to particular servers based on which interface it was
received.
For example, you can configure the system to match on the DHCP packet to
determine whether the request originated from a cable modem, a CPE, a
specific interface, or a specific MAC address; wildcards can be used to match
portions of a MAC address. In the event of a match, you can configure the
DHCP relay agent to forward the request to a list of up to three DHCP
servers, or configure the agent to drop the request.