DOCSIS

Data Over Cable Service Interface Specification (DOCSIS /ˈdɒksɪs/) is an international telecommunications standard that permits the addition of high-bandwidth data transfer to an existing cable television (CATV) system. It is used by many cable television operators to provide Internet access (see cable Internet) over their existing hybrid fiber-coaxial (HFC) infrastructure. The version numbers are sometimes prefixed with simply 'D' instead of 'DOCSIS' (e.g. D3 for DOCSIS 3). Data Over Cable Service Interface Specification (DOCSIS /ˈdɒksɪs/) is an international telecommunications standard that permits the addition of high-bandwidth data transfer to an existing cable television (CATV) system. It is used by many cable television operators to provide Internet access (see cable Internet) over their existing hybrid fiber-coaxial (HFC) infrastructure. The version numbers are sometimes prefixed with simply 'D' instead of 'DOCSIS' (e.g. D3 for DOCSIS 3). DOCSIS was developed by CableLabs and contributing companies, including 3Com, ARRIS, BigBand Networks, Broadcom, Cisco, Comcast, Conexant, Correlant, Cox, Harmonic, Hitron Technologies, Intel, Motorola, Netgear, Technicolor, Terayon, Time Warner Cable, and Texas Instruments. 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 (CM) 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 data rates. In 2010, the U.S. Federal Communications Commission (FCC) urged U.S. providers to make 100 Mbit/s a standard bandwidth available to 100 million households before 2020. In 1994, 802.14 was chartered to develop a media access control over an HFC. In 1995, Multimedia Cable Network System (MCNS) was formed. The original partners were: TCI, Time Warner, Comcast, COX. Later, Continental and Rogers joined the group. In June 1996, SCTE formed the Data Standards Subcommittee to begin work on establishing national standards for high-speed data over cable plant. July 1997: SCTE DSS voted in the affirmative on document DSS 97-2. This standard is based on the well-known DOCSIS specification. The standard was also submitted to International Telecommunications Union Telecommunications Standardization Sector (ITU-T) and has been adopted as ITU-T J.112 Annex B. As frequency allocation bandwidth plans differ between United States and European CATV systems, DOCSIS standards earlier than 3.1 have been modified for use in Europe. These modifications were published under the name EuroDOCSIS. The differences between the bandwidths exist because European cable TV conforms to PAL/DVB-C standards of 8 MHz RF channel bandwidth and North American cable TV conforms to NTSC/ATSC standards which specify 6 MHz per channel. The wider channel bandwidth in EuroDOCSIS architectures permits more bandwidth to be allocated to the downstream data path (toward the user). EuroDOCSIS certification testing is executed by Belgian company Excentis (formerly known as tComLabs), while DOCSIS certification testing is executed by CableLabs. Typically, customer premises equipment receives 'certification', while CMTS equipment receives 'qualification'. The ITU Telecommunication Standardization Sector (ITU-T) has approved the various versions of DOCSIS as international standards. DOCSIS 1.0 was ratified as ITU-T Recommendation J.112 Annex B (1998), but it was superseded by DOCSIS 1.1 which was ratified as ITU-T Recommendation J.112 Annex B (2001). Subsequently, DOCSIS 2.0 was ratified as ITU-T Recommendation J.122. Most recently, DOCSIS 3.0 was ratified as ITU-T Recommendation J.222 (J.222.0, J.222.1, J.222.2, J.222.3). Note: While ITU-T Recommendation J.112 Annex B corresponds to DOCSIS/EuroDOCSIS 1.1, Annex A describes an earlier European cable modem system ('DVB EuroModem') based on ATM transmission standards. Annex C describes a variant of DOCSIS 1.1 that is designed to operate in Japanese cable systems. The ITU-T Recommendation J.122 main body corresponds to DOCSIS 2.0, J.122 Annex F corresponds to EuroDOCSIS 2.0, and J.122 Annex J describes the Japanese variant of DOCSIS 2.0 (analogous to Annex C of J.112). DOCSIS provides great variety in options available at Open Systems Interconnection (OSI) layers 1 and 2, the physical and data link layers.