Cisco CloudCenter: Get the Hybrid IT Advantage

Data Over Cable Service Interface Specification (DOCSIS)

Definition - What does Data Over Cable Service Interface Specification (DOCSIS) mean?

Data over cable service interface specification (DOCSIS) is an internationally recognized standard allowing high speed data transfer on existing cable TV systems (CATVSs) used by many cable operators to provide Internet access to their customers through a cable modem. The latest version of the standard also supports high definition televisions (HDTVs).

The standard was approved by the International Telecommunication Union (ITU) in 1998.

Techopedia explains Data Over Cable Service Interface Specification (DOCSIS)

The first version of DOCSIS was issued in March 1997. Later it was enhanced in response to increased demand for symmetric services such as IP telephony. Version 2.0 was released in December 2001. In August 2006 version 3.0 was released with significantly increased transmission speeds, both upstream and downstream. This version also included support for Internet protocol version 6 (IPv6). Cross-version compatibility has been maintained. However, the transmission speed will only be at the speed of the oldest version. As of late 2010, the fastest downloads were 120 Mbit/s (and 20 Mbit/s upload) in Canada, with the next fastest 107 Mbits/s in the US.

All cable modems today are in compliance with DOCSIS, which exists in two versions named DOCSIS for the USA and EuroDOCSIS for Europe. These were required because of the differences between the two systems: the European PAL (phase alternating line), which is an analog color television encoding system; and the USA’s analog NTSC (National Television System Committee), which is the first widely adopted broadcast color system. In June 2009, NTSC switched to the digital ATSC (Advanced Television Systems Committee) in the USA. Each operates on different radio frequency (RF) channels, 6 MHz in the USA and 8 MHz for Europe. Except for some systems in Japan, nearly all today’s cable modem systems use a version of DOCSIS.

Using layers 1 and 2 of the Open Systems Interconnection (OSI) layers, DOCSIS enables upstream transmission speeds of 30.72 Mbits/s per 6 MHz channel and 10.24 Mbits/s per 3 MHz channel. All three versions (USA, Europe and Japan) enable downstream speeds of up to 42.88 Mbit/s per 6 MHz channel (USA) or 55.62 Mbit/s per 8 MHz channel (Europe). However, with hardware to support the minimum number of four coupled channels, DOCSIS 3.0 has maximum possible downstream/upstream speeds of 160/120 Mbit/s.

Share this:

Connect with us

Email Newsletter

Join thousands of others with our weekly newsletter

The 4th Era of IT Infrastructure: Superconverged Systems
The 4th Era of IT Infrastructure: Superconverged Systems:
Learn the benefits and limitations of the 3 generations of IT infrastructure – siloed, converged and hyperconverged – and discover how the 4th...
Approaches and Benefits of Network Virtualization
Approaches and Benefits of Network Virtualization:
Businesses today aspire to achieve a software-defined datacenter (SDDC) to enhance business agility and reduce operational complexity. However, the...
Free E-Book: Public Cloud Guide
Free E-Book: Public Cloud Guide:
This white paper is for leaders of Operations, Engineering, or Infrastructure teams who are creating or executing an IT roadmap.
Free Tool: Virtual Health Monitor
Free Tool: Virtual Health Monitor:
Virtual Health Monitor is a free virtualization monitoring and reporting tool for VMware, Hyper-V, RHEV, and XenServer environments.
Free 30 Day Trial – Turbonomic
Free 30 Day Trial – Turbonomic:
Turbonomic delivers an autonomic platform where virtual and cloud environments self-manage in real-time to assure application performance.