DHCP and Broadband Subscriber Management Overview

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You use DHCP in broadband networks to provide IP address configuration and service provisioning. DHCP, historically a popular protocol in LANs, works well with Ethernet connectivity and is becoming increasingly popular in broadband networks as a simple, scalable solution for assigning IP addresses to subscriber home PCs, set-top boxes (STBs), and other devices.

The JUNOS broadband subscriber management solution currently supports the following DHCP allocation models:

DHCP Local Server
DHCP Relay

DHCP uses address assignment pools from which to allocate subscriber addresses. Address-assignment pools support both dynamic and static address assignment:

Dynamic address assignment—A subscriber is automatically assigned an address from the address-assignment pool.
Static address assignment—Addresses are reserved and always used by a particular subscriber.

Note: Addresses that are reserved for static assignment are removed from the dynamic address pool and cannot be assigned to other clients.

Extended DHCP Local Server and Broadband Subscriber Management Overview

You can enable the services router to function as an extended DHCP local server. As an extended DHCP local server the services router, and not an external DHCP server, provides an IP address and other configuration information in response to a client request. The extended DHCP local server supports the use of external AAA authentication services, such as RADIUS, to authenticate DHCP clients.

Extended DHCP Relay and Broadband Subscriber Management Overview

You can configure extended DHCP relay options on the router and enable the router to function as a DHCP relay agent. A DHCP relay agent forwards DHCP request and reply packets between a DHCP client and a DHCP server. You can use DHCP relay in carrier edge applications such as video and IPTV to obtain configuration parameters, including an IP address, for your subscribers. The extended DHCP relay agent supports the use of external AAA authentication services, such as RADIUS, to authenticate DHCP clients.