Introduction

Cable operators are interested in deploying high-speed data communications systems on cable television systems. A series of interface specifications has been prepared that will permit the early definition, design, development, and deployment of packet data over cable systems.
The data over cable service interface specification (DOCSIS) specifies the protocol for exchanging bidirectional transfer of Internet protocol (IP) traffic, between the cable system headend and customer locations.

When a cable company offers Internet access over the cable, Internet information can use the same cables. Putting both upstream and downstream data on the cable television system requires two types of equipment: a cable modem on the customer end and a cable modem termination system (CMTS) at the cable provider's end.
The CMTS takes the traffic coming in from a group of customers on a single channel and routes it to an Internet service provider (ISP) for connection to the Internet. At the head-end, the cable providers will have, or lease space for a third-party ISP to have, servers for accounting and logging, Dynamic Host Configuration Protocol (DHCP) for assigning and administering the IP addresses of all the cable system's users, and control servers.

RDK-B was designed to support any wide area network (WAN). Gateways using RDK-B may provide a DOCSIS interface, but that DOCSIS code is typically tied to a particular piece of silicon and may even be provided by that silicon vendor. And the core philosophy of RDK-B was to be hardware independent.

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