Data Over Cable Service Interface Specification (DOCSIS) is an international telecommunications standard that permits the addition of high-speed data transfer to an existing cable TV (CATV) system. It is employed by many cable television operators to provide Internet access (the cable Internet) over their existing hybrid fiber-coaxial (HFC) infrastructure.

DOCSIS was developed by CableLabs and contributing companies including ARRIS, BigBand Networks, Broadcom, Cisco, Conexant, Correlant, Harmonic, Intel, Motorola, Netgear, Technicolor, Terayon, and Texas Instruments.

DOCSIS® Specifications — DOCSIS® 2.0 Interface

The first specification, version 1.0, was issued in March 1997. In April 1999, the revision 1.1 specification added full standardization, quality of service (QoS) capabilities). Because of increased demand for symmetric services such as IP telephony, DOCSIS was revised to enhance upstream transmission speeds; DOCSIS 2.0 was released in December 2001.

Most recently, the specification was revised to significantly increase transmission speeds (this time both upstream and downstream) and introduce support for Internet Protocol version 6 (IPv6). This version, DOCSIS 3.0, was released in August 2006. Cross-version compatibility has been maintained across all versions of DOCSIS, with the devices falling back to the highest supported version in common between both endpoints: cable modem and cable modem termination system (CMTS). For example, if one has a cable modem that only supports DOCSIS 1.0, and the system is running 2.0, the connection will be established at DOCSIS 1.0 speeds.

As of the end of 2011, the fastest deployments in North America are expected to be Shaw Cable's announced 250 Mbit/s download 15 Mbit/s upload, which will be implemented in phases, and Videotron's 200 Mbit/s download / 30 Mbit/s upload service in Quebec City,[2] followed closely by existing 107 Mbit/s deployments in the USA. The U.S. Federal Communications Commission (FCC) urged U.S. providers to make 100 Mbit/s a standard speed available to 100 million households before 2020.[3] Of wired technologies, only DOCSIS, FIOS, E-line (advanced powerline networking with bandwidth equivalent to fiber) and Ethernet in the first mile are likely to achieve this speed on a large scale in that time frame.

In the UK, broadband provider Virgin Media announced on 20 April 2011 an intention to start trials with download speeds of 1.5 Gbit/s and upload of 150 Mbit/s based on DOCSIS3.0.

DOCSIS 1.0 was preceded by numerous proprietary cable modem products. The DOCSIS standard included functional elements from the LANcity provisioning process (DHCP/TFTP/TOD), the Motorola 64 QAM set top boxes with Broadcom chipsets, and the Motorola Proprietary cable modem system (elements of the upstream MAC/PHY layer). These choices were made to enhance the product success as a result of field proven technology.


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