IPTV via DOCSIS

Data over Cable Service Interface Specification (DOCSIS)
EuroDOCSIS, were originally designed to carry high speed Internet traffic over wide area networks. The specifications have evolved over the years and the latest version of DOCSIS provides enough capacity to support the delivery
of IPTV services across HFC networks. Both DOCSIS and EuroDOCSIS are discussed in the following sections.

Understanding DOCSIS Two-way cable TV networks deployed in the United States that support high speed broadband services are likely to use aspecification called DOCSIS. CableLabs, a research and development consortium of cable television system operators representing the Americas, developed thistechnology. The specification defines the protocols and modulation formats used fordelivering IP broadband services over a cable TV network.
The first revision of the technology, known as DOCSIS 1.0, was approved as astandard by the ITU in 1998 and there has been a family of DOCSIS specifications issued over the past 8 years. An overview of the technical features supported by each generation of DOCSIS technology is presented in Table 2.3. The DOCSIS versions through to DOCSIS 2.0 support a data rate of approximately 40 Mbps on the downstream. This bandwidth capacity is typically used to service a number of high speed Internet access subscribers. If this bandwidth was to be utilized for delivering IPTV multicast TV channels, then 10 or possibly 15 IPTV streams could be simultaneously provided on any individual downstream channel. This calculation is based on streaming 10 15 standard definition IPTV channels that each occupy between 2.5 and 4 Mbps of bandwidth.
Once the channels are configured, cable operators use a networking technique called multicasting (described in Chapter 3) to assign multiple users to each IPTVstream.
The latest release of the specification, DOCSIS 3.0, enhances cable TVoperator’s capacity for delivering IP-VoD and multicast IPTV services to theircustomers. DOCSIS 3.0 is a next generation wideband technology that allows cableoperators to bond multiple channels together to form high speed IP pipes capable ofoperating at hundreds of megabits per second. In North America 6 MHz channelsare bonded together whereas in Europe the channels bonded together have acapacity of 8 MHz. Note that the bonding feature applies to both upstream and downstream channels. Other features of DOCSIS 3.0 include its in-built support for next generation IPv6 management addresses. Advanced support for improved network security, IP multicasting and associated QoS mechanisms are all major features of DOCSIS 3.0.
Inside the DOCSIS 3.0 Technical Specification Before discussing the DOCSIS technical specification, it is first helpful to gain a high level understandingof how an end-to-end DOCSIS 3.0 system operates. A highly simplified graphical view of an end-to-end DOCSIS 3.0 system.
As illustrated the cable modem communicates via a two-way HFC network to adevice located in the headend called a Cable Modem Termination System (CMTS).
DOCSIS defines two variants of CMTSs an integrated CMTS and a modularCMTS. An integrated CMTS consists of a single unit with RF interfaces and upstream network interface(s). A modular CMTS (M-CMTS) implements the upstream RF interfaces and the network interface(s); however, the downstream traffic is processed separately via cable modulators. also includes a connection from the CMTS to network management system (NMS) and provisioning systems. The provisioning system comprises of a number of servers that provide different types of functionality including dynamic host configuration protocol (DHCP) IP address allocation, cable modem configuration parameters, and providing time services. The NMS provides monitoring andmanagement services to the end-to-end networking architecture. A connection to the Internet is also provided to facilitate subscriber’s access to high speed Internet access service. The DOCSIS 3.0 technology itself is a significant standard, which is broken down into four specifications.