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Ter info. Is wel in engels Maar als chello dit ook gaat invoeren wordt het zeer leuk in kabeltjesland
Overview
With more than 25 million high-speed Internet access customers in North America, the cable modem has become the broadband connection of choice for many Internet users. In fact, cable modem deployments have outstripped the nearest rival broadband technology, Digital Subscriber Line (DSL), by a significant margin. Yet, there is still room for growth since the total penetration of broadband access technologies in the U.S. is currently only 33 percent. (All statistics as of Q1 2005, Kinetic Strategies, Inc.)
Furthermore, the cable Internet Protocol (IP) realm is at the brink of an explosion of new services, fueled by new specifications including: DOCSIS® 3.0, PacketCable™ Multimedia (PCMM™) and PacketCable™ 2.0, the integration of Universal Plug & Play (UPnP) support in CableHome®, and the DOCSIS® Set-top Gateway (DSG).
For several years, cable television operators have been transitioning from a traditional core business of entertainment programming to a position as full-service providers of video, voice, and data telecommunications services. DOCSIS cable modems are among the fundamental elements making this transition possible. To date, the most successful and cost-effective method for providing high-speed data services is via cable modems compliant with the DOCSIS specifications.
DOCSIS® Specifications
The four successive versions of the DOCSIS cable modem specifications: DOCSIS 1.0, DOCSIS 1.1, and DOCSIS 2.0, and, now in development, DOCSIS 3.0, provide increasing levels of capabilities and functionality, while maintaining multi-vendor interoperability and full backward and forward compatibility of DOCSIS.
DOCSIS 1.0 specifications include technology that was available in the 1995–1996 timeframe, and have become very widely deployed around the world.
DOCSIS 1.1 specifications provide improved operational flexibility, security, and Quality-of-Service (QoS) features that enable real-time services.
DOCSIS 2.0 specifications provide dramatically increased upstream throughput for symmetric services.
DOCSIS 3.0 specifications are currently in development at CableLabs and will include a number of enhancements, most notably, channel bonding and support for IPv6. Channel bonding provides cable operators with a flexible way to increase upstream and downstream throughput to customers, with data rates in the hundreds of megabits and potentially gigabits per second.
Standardization of DOCSIS Specifications
All three published versions of the DOCSIS specifications have been formally approved by national, regional, and international standards development organizations such as the Society for Cable Telecommunications Engineers (SCTE), the European Telecommunications Standards Institute (ETSI), and the International Telecommunications Union (ITU).
Services
DOCSIS 1.0 provides delivery of high-speed data on cable modems to the cable industry platform.
DOCSIS 1.1 enables provision of Voice-over-IP telephony (VoIP), interactive gaming, and tier-based services.
DOCSIS 2.0 increases upstream throughput to 30 Mbps, resulting in an increase in the capacity to deliver high-speed data.
DOCSIS 3.0 will increase the capacity to a minimum of 160 Mbps downstream to customers and by a minimum of 120 Mbps upstream.
Cable Modems
Digital data signals are transmitted over radio frequency (RF) carrier signals on a cable system. For two-way communication, there is one carrier signal that carries data in the “downstream” direction (from the cable network to the customer), and another that carries data in the “upstream” direction (from the customer to the cable network). Cable modems are devices at the subscriber premises that convert digital information into a modulated RF signal in the upstream direction, and convert the RF signals to digital information in the downstream direction. Another piece of equipment, called a cable modem termination system (CMTS), performs the converse operation for multiple subscribers at the cable operator's headend.
Typically, a few hundred users may share a 6-MHz downstream channel and one or more upstream channels. The downstream channel occupies the space of a single television transmission channel in the cable operator's channel lineup. It is compatible with digital set-top MPEG transport stream modulation (64 or 256 QAM), and can provide up to 40 Mbps. In DOCSIS 1.0 and 1.1, the upstream channels can be up to 3.2-MHz wide, and can deliver up to 10 Mbps-per-channel. In DOCSIS 2.0, upstream channels can deliver up to 30 Mbps over channels as wide as 6.4 MHz. A media access control (MAC) layer coordinates shared access to the upstream bandwidth. In DOCSIS 3.0, several downstream and several upstream channels will be “bonded” together to multiply the bandwidth delivered to each customer.
Shared Bandwidth
Because the bandwidth on the upstream and downstream channels is shared over a number of customers, the usage of that bandwidth is much more efficient than the alternative of a point-to-point dedicated link. Since most communication links are idle for a significant period of time, aggregating and sharing bandwidth allows the otherwise unused capacity available from idle users to be taken advantage of by users who have data to send. For packetized data services, the term “statistical multiplexing” is often used to describe the efficiency gains realized by sharing bandwidth. Through proper traffic engineering and capacity planning, operators can ensure that network bottlenecks don't occur during peak usage times.
Security and Privacy
Although the physical layout and shared medium of the cable plant means that the data for each user passes by every other user on that section of the plant, the DOCSIS specifications ensure that every user's data is kept private through the use of encryption technology. Furthermore, DOCSIS 1.1, 2.0, and 3.0 provide additional security tools, including a mechanism for the operator to prevent theft of service by requiring that each modem authenticate itself using a digital certificate, a secure method to download new operational software to a modem, and a way to encrypt high-value “multicast” traffic and provide decryption keys only to those customers who are authorized for the service.
Overview
With more than 25 million high-speed Internet access customers in North America, the cable modem has become the broadband connection of choice for many Internet users. In fact, cable modem deployments have outstripped the nearest rival broadband technology, Digital Subscriber Line (DSL), by a significant margin. Yet, there is still room for growth since the total penetration of broadband access technologies in the U.S. is currently only 33 percent. (All statistics as of Q1 2005, Kinetic Strategies, Inc.)
Furthermore, the cable Internet Protocol (IP) realm is at the brink of an explosion of new services, fueled by new specifications including: DOCSIS® 3.0, PacketCable™ Multimedia (PCMM™) and PacketCable™ 2.0, the integration of Universal Plug & Play (UPnP) support in CableHome®, and the DOCSIS® Set-top Gateway (DSG).
For several years, cable television operators have been transitioning from a traditional core business of entertainment programming to a position as full-service providers of video, voice, and data telecommunications services. DOCSIS cable modems are among the fundamental elements making this transition possible. To date, the most successful and cost-effective method for providing high-speed data services is via cable modems compliant with the DOCSIS specifications.
DOCSIS® Specifications
The four successive versions of the DOCSIS cable modem specifications: DOCSIS 1.0, DOCSIS 1.1, and DOCSIS 2.0, and, now in development, DOCSIS 3.0, provide increasing levels of capabilities and functionality, while maintaining multi-vendor interoperability and full backward and forward compatibility of DOCSIS.
DOCSIS 1.0 specifications include technology that was available in the 1995–1996 timeframe, and have become very widely deployed around the world.
DOCSIS 1.1 specifications provide improved operational flexibility, security, and Quality-of-Service (QoS) features that enable real-time services.
DOCSIS 2.0 specifications provide dramatically increased upstream throughput for symmetric services.
DOCSIS 3.0 specifications are currently in development at CableLabs and will include a number of enhancements, most notably, channel bonding and support for IPv6. Channel bonding provides cable operators with a flexible way to increase upstream and downstream throughput to customers, with data rates in the hundreds of megabits and potentially gigabits per second.
Standardization of DOCSIS Specifications
All three published versions of the DOCSIS specifications have been formally approved by national, regional, and international standards development organizations such as the Society for Cable Telecommunications Engineers (SCTE), the European Telecommunications Standards Institute (ETSI), and the International Telecommunications Union (ITU).
Services
DOCSIS 1.0 provides delivery of high-speed data on cable modems to the cable industry platform.
DOCSIS 1.1 enables provision of Voice-over-IP telephony (VoIP), interactive gaming, and tier-based services.
DOCSIS 2.0 increases upstream throughput to 30 Mbps, resulting in an increase in the capacity to deliver high-speed data.
DOCSIS 3.0 will increase the capacity to a minimum of 160 Mbps downstream to customers and by a minimum of 120 Mbps upstream.
Cable Modems
Digital data signals are transmitted over radio frequency (RF) carrier signals on a cable system. For two-way communication, there is one carrier signal that carries data in the “downstream” direction (from the cable network to the customer), and another that carries data in the “upstream” direction (from the customer to the cable network). Cable modems are devices at the subscriber premises that convert digital information into a modulated RF signal in the upstream direction, and convert the RF signals to digital information in the downstream direction. Another piece of equipment, called a cable modem termination system (CMTS), performs the converse operation for multiple subscribers at the cable operator's headend.
Typically, a few hundred users may share a 6-MHz downstream channel and one or more upstream channels. The downstream channel occupies the space of a single television transmission channel in the cable operator's channel lineup. It is compatible with digital set-top MPEG transport stream modulation (64 or 256 QAM), and can provide up to 40 Mbps. In DOCSIS 1.0 and 1.1, the upstream channels can be up to 3.2-MHz wide, and can deliver up to 10 Mbps-per-channel. In DOCSIS 2.0, upstream channels can deliver up to 30 Mbps over channels as wide as 6.4 MHz. A media access control (MAC) layer coordinates shared access to the upstream bandwidth. In DOCSIS 3.0, several downstream and several upstream channels will be “bonded” together to multiply the bandwidth delivered to each customer.
Shared Bandwidth
Because the bandwidth on the upstream and downstream channels is shared over a number of customers, the usage of that bandwidth is much more efficient than the alternative of a point-to-point dedicated link. Since most communication links are idle for a significant period of time, aggregating and sharing bandwidth allows the otherwise unused capacity available from idle users to be taken advantage of by users who have data to send. For packetized data services, the term “statistical multiplexing” is often used to describe the efficiency gains realized by sharing bandwidth. Through proper traffic engineering and capacity planning, operators can ensure that network bottlenecks don't occur during peak usage times.
Security and Privacy
Although the physical layout and shared medium of the cable plant means that the data for each user passes by every other user on that section of the plant, the DOCSIS specifications ensure that every user's data is kept private through the use of encryption technology. Furthermore, DOCSIS 1.1, 2.0, and 3.0 provide additional security tools, including a mechanism for the operator to prevent theft of service by requiring that each modem authenticate itself using a digital certificate, a secure method to download new operational software to a modem, and a way to encrypt high-value “multicast” traffic and provide decryption keys only to those customers who are authorized for the service.