Cable modem - Wikipedia, the free encyclopedia. Motorola SURFboard SBV6. E Euro. DOCSIS 3. A cable modem is a type of network bridge and modem that provides bi- directional data communication via radio frequency channels on a hybrid fibre- coaxial (HFC) and radio frequency over glass (RFo. G) infrastructure.
99 5.1 COMPUTER NETWORKS (Common with Information Technology) L T P 3 - 3 RATIONALE The future of computer technology is in computer networks. Global connectivity can be achieved through computer networks. Cable modems are primarily used to deliver broadband Internet access in the form of cable Internet, taking advantage of the high bandwidth of a HFC and RFo. G network. They are commonly deployed in Australia, Europe, Asia and the Americas. History[edit]MITRE Cablenet[edit]Internet Experiment Note (IEN) 9. RF cable modem system. From pages 2 and 3 of IEN 9. The Cable- Bus System. The MITRE/Washington Cablenet system is based on a technology developed at MITRE/Bedford. Similar cable- bus systems are in operation at a number of government sites, e. Walter Reed Army Hospital, and the NASAJohnson Space Center, but these are all standalone, local- only networks. The system uses standard Community Antenna Television (CATV) coaxial cable and microprocessor based Bus Interface Units (BIUs) to connect subscriber computers and terminals to the cable. The cable bus consists of two parallel coaxial cables, one inbound and the other outbound. In the late 1990s, a consortium of US cable operators, known as 'MCNS' formed to quickly develop an open and interoperable cable modem specification. The group essentially combined technologies from the two dominant.The inbound cable and outbound cable are connected at one end, the headend, and electrically terminated at their other ends. This architecture takes advantage of the well developed unidirectional CATV components.[2] The topology is dendritic (i. The BIUs contain Radio Frequency (RF) modems which modulate a carriersignal to transmit digitalinformation using 1 MHz of the available bandwidth in the 2. MHz frequency range. The remainder of the 2. MHz bandwidth can be used to carry other information channels, such as off- the- air. TV, FM, closed circuit TV, or a voicetelephone system, or, other digital channels. The data rate of our test- bed system is 3. IEEE 8. 02. 3b (1. BROAD3. 6)[edit]The IEEE8. Committee defined 1. BROAD3. 6 in 8. 02. Mbps. IEEE 8. 02. Ethernet broadband system to run up to 3,6. CATV coax network cabling. The word broadband as used in the original IEEE 8. FDM) channel bands as opposed to digital basebandsquare- waveformmodulations (also known as line coding), which begin near zero Hz and theoretically consume infinitefrequency bandwidth. In real- world systems, higher- order signalcomponents become indistinguishable from background noise.) In the market 1. BROAD3. 6 equipment was not developed by many vendors nor deployed in many user networks as compared to equipment for IEEE 8. Ethernetbaseband standards such as 1. BASE5 (1. 98. 3), 1. BASE2 (1. 98. 5), 1. BASE- T (1. 99. 0), etc. IEEE 8. 02. 7[edit]The IEEE 8. Committee also specified a broadband CATV digital networking standard in 1. However, like 1. 0BROAD3. Hybrid networks[edit]Hybrid Networks developed, demonstrated and patented the first high- speed, asymmetrical cable modem system in 1. A key Hybrid Networks insight was that in the nascent days of the Internet, data downloading constitutes the majority of the data traffic, and this can be served adequately with a highly asymmetrical data network (i. This allowed CATV operators to offer high speed data services immediately without first requiring an expensive system upgrade. Also key was that it saw that the upstream and downstream communications could be on the same or different communications media using different protocols working in each direction to establish a closed loop communications system. The speeds and protocols used in each direction would be very different. The earliest systems used the public switched telephone network (PSTN) for the return path since very few cable systems were bi- directional. Later systems used CATV for the upstream as well as the downstream path. Hybrid's system architecture is used for most cable modem systems today. LANcity[edit]LANcity was an early pioneer in cable modems, developing a proprietary system that was widely deployed in the U. S. LANcity, which was led by the Iranian- American engineer Rouzbeh Yassini, was then acquired by Nortel, which eventually spun the cable modem business off as ARRIS. ARRIS continues to make cable modems and CMTS equipment compliant with the DOCSIS standard. Zenith homeworks[edit]Zenith offered a cable modem technology using its own protocol which it introduced in 1. The Zenith Cable Modem technology was used by several cable television systems in the United States and other countries, including Cox Communications San Diego, Knology in the Southeast United States, Ameritech's Americast service (later to be sold off to Wide Open West after the SBC / Ameritech merger), and Cogeco in Hamilton Ontario.[5] Zenith Homeworks used BPSK (Bi- Phase Shift Keyed) modulation to achieve 5. Kbit/sec in 6. 00 k. Hz, or 4 Mbit/sec in 6 MHz.[6]Com. DOCSIS standardization. The Com. 21 system used a Com. Controller as central bridge in CATV network head- ends, the Com. Port cable modem in various models and the NMAPS management system using HP Open. View as platform. Later they also introduced a return path multiplexer to overcome noise problems when combining return path signals from multiple areas. The proprietary protocol was based on Asynchronous Transfer Mode (ATM). The central Com. Controller switch was a modular system offering one downstream channel (transmitter) and one management module. The remaining slots could be used for upstream receivers (2 per card), dual Ethernet 1. Base. T and later also Fast- Ethernet and ATM interfaces. The ATM interface became the most popular, as it supported the increasing bandwidth demands and also supported VLANs. Com. 21 developed a DOCSIS modem, but the company filed for bankruptcy in 2. The DOCSIS CMTS assets of COM2. ARRIS. CDLP was a proprietary system manufactured by Motorola. CDLP customer premises equipment (CPE) was capable of both PSTN (telephone network) and radio frequency (cable network) return paths. The PSTN- based service was considered 'one- way cable' and had many of the same drawbacks as satellite Internet service; as a result, it quickly gave way to "two- way cable." Cable modems that used the RF cable network for the return path were considered 'two- way cable', and were better able to compete with the bi- directional digital subscriber line (DSL) service. The standard is in little use now while new providers use, and existing providers having changed to the DOCSIS standard. The Motorola CDLP proprietary Cyber. SURFR is an example of a device that was built to the CDLP standard, capable of a peak 1. Mbit/s downstream and 1. Mbit/s upstream. CDLP supported a maximum downstream bandwidth of 3. Mbit/s which could be reached by using several cable modems. The Australian ISP Big. Pond employed this system when it started cable modem tests in 1. For a number of years cable Internet access was only available in Sydney, Melbourne and Brisbane via CDLP. This network ran parallel to the newer DOCSIS system for several years. In 2. 00. 4, the CDLP network was terminated and replaced by DOCSIS. CDLP has been also rolled out at the French cable operator Numericable before upgrading its IP broadband network using DOCSIS. DVB/DAVIC[edit]Digital Video Broadcasting (DVB) and Digital Audio Visual Council (DAVIC) are European- formed organizations that developed some cable modem standards. However, these standards have not been as widely adopted as DOCSIS. IEEE 8. 02. 1. 4[edit]In the mid- 1. IEEE 8. 02 committee formed a subcommittee (8. IEEE 8. 02. 1. 4 developed a draft standard, which was ATM- based. However, the 8. 02. North American multi system operators (MSOs) instead backed the then- fledgling DOCSIS 1. IP- based (with extension codepoints to support ATM[8] for Qo. S in the future). MSOs were interested in quickly deploying service to compete for broadband Internet access customers instead of waiting on the slower, iterative, and deliberative processes of standards development committees. Albert A. Azzam was Secretary of the IEEE 8. Working Group,[9] and his book, High- Speed Cable Modems,[1. Although the Internet Engineering Task Force (IETF) generally does not generate complete cable modem standards, the IETF chartered Working Groups (WGs) that produced various standards related to cable modem technologies (including 8. DOCSIS, Packet. Cable, and others). In particular, the IETF WGs on IP over Cable Data Network (IPCDN)[1. IP over Digital Video Broadcasting (DVB)[1. Simple Network Management Protocol (SNMP) Management Information Bases (MIBs) for cable modems and other networking equipment that operates over CATV networks. In the late 1. 99. US cable operators, known as "MCNS" formed to quickly develop an open and interoperable cable modem specification. The group essentially combined technologies from the two dominant proprietary systems at the time, taking the physical layer from the Motorola. CDLP system and the MAC layer from the LANcity system. When the initial specification had been drafted, the MCNS consortium handed over control of it to Cable. Labs which maintained the specification, promoted it in various standards organizations (notably SCTE and ITU), developed a certification testing program for cable modem equipment, and has since drafted multiple extensions to the original specification. While deployed DOCSIS RFI 1. DOCSIS RFI 1. 0 Interim- 0. Qo. S extensions and mechanisms using Int. Serv, RSVP, RTP, and Synchronous Transfer Mode (STM) telephony (as opposed to ATM).[8]DOCSIS RFI 1. Qo. S mechanisms to DOCSIS. DOCSIS 2. 0 added support for S- CDMAPHY, while DOCSIS 3. IPv. 6 support and channel bonding to allow a single cable modem to use concurrently more than one upstream channel and more than one downstream channel in parallel. Virtually all cable modems operating in the field today are compliant with one of the DOCSIS versions. Because of the differences in the European PAL and USA's NTSC systems two main versions of DOCSIS exist, DOCSIS and Euro.
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