Broadband Access: Wireline and Wireless - Alternatives for Internet Services

11The DOCSIS (Data-Over-Cable Service Interface Specification) Protocol

11.1 General Introduction

Cable television companies, commonly known as Multiple System Operators (MSOs), have traditionally specialized in delivering video signals to subscribers. In order to compete with telephone network operators for triple-play services, MSOs have upgraded their networks to support broadband data and voice service. A key element of this upgrade is the deployment of an IP-based core data network. This network enables high-speed data access, which has become the “killer” service for the MSOs. The customer applications making use of their high-speed IP networks include online gaming, the acquisition and sharing of music, instant messaging, and video delivery. IPTV (Internet Protocol Television) on-demand video delivery is a service pioneered by the MSOs. Voice over IP (VoIP) has also become an important MSO application. The Data-Over-Cable Service Interface Specification (DOCSIS) is the heart of providing IP-based services over the access network to the subscribers. This chapter focuses on DOCSIS, especially its physical [1] and data link layers [2], and briefly mentions other related companion protocols.

11.2 Introduction to MSO Networks

From its inception, the community antenna television (CATV) network, also commonly known as the cable television network, was designed for broadcast service delivery. The network was constructed with a head end office feeding the broadcast TV signals ...