The Data Over Cable Service Interface Specification (DOCSIS) is the potential CATVstandard of the USA, which is supported by all well-known UScable modem manufacturers. In 1997, the first version of DOCSIS was published by CableLab, in which basic functionalities for quality of service(QoS) were already implemented. \nAlready in 1999, the enhanced version of DOCSIS V1.1 was released, which especially considered enhancements for the transmission of Internettelephony and for other time-critical services, e.g. standardized IP multicast, upstreamfragmentationvia the head-end station and complete QoS features including Available Bit Rate(ABR), Variable Bit Rate(VBR) and Constant Bit Rate(CBR). In addition, privacy is protected with digitalsignatures through a public keyprocess. Each user can be authenticated and receives only the data assigned to him. In the DOCSIS 2.0 version, a transmission channel is permanently assigned to the subscriber. This means that the bandwidth is not scalable or expandable. A single channel has a data rate of approximately 50 Mbps. In practical use, one or two subscribers making downloads at high data rates can restrict the data rate of other subscribers. DOCSIS protocol layers in relation to the OSI layer modelVersion 3.0 of DOCSIS \nIn the more recent DOCSIS 3.0 version, channel bundling is supported, as are IPv6, quality of service (QoS), Internet television(IPTV) and IP multicast. Channel bundling works dynamically and distributes the data over the available channels. A total of 16 channels are available for the downstream in this version, and even more if necessary, onto which the data can be distributed. This should not result in any bottlenecks, since the data rate of 400 Mbit\/s is distributed among the subscribers for 8 channels and 800 Mbit\/s for 16 channels. For upstream, the DOCSIS standard provides for three 7 MHz wide channels, namely in the lower VHF range on TV channels 2, 3 and 4 in the frequency range between 47 MHz and 68 MHz. The data rate can be 100 Mbit\/s and higher. The 16 channels for downstream are in the mid UHF range between 630 MHz and 862 MHz. \nSince the specifications of the European cable distribution networks differ from those of the U.S., specifications for European cable networks were presented in 1998, the EuroDOCSIS. \nIn the U.S. DOCSIS, which is standardized by the International Telecommunication Union(ITU) under Recommendation J.112, the forward channel has a bandwidth of 6 MHz, and the return channel is in the frequency range between 5 MHz and 42 MHz and has selectable bandwidths. All changes of EuroDOCSIS compared to the American version refer exclusively to the physical layer of the OSI reference model, all other layers, especially the MAC layer, remain unchanged.