Contention ratio

Last updated

In computer networking, the contention ratio is the ratio of the potential maximum demand to the actual bandwidth. The higher the contention ratio, the greater the number of users that may be trying to use the actual bandwidth at any one time and, therefore, the lower the effective bandwidth offered, especially at peak times. [1] A contended service is a service which offers the users of the network a minimum statistically guaranteed contention ratio, while typically offering peaks of usage of up to the maximum bandwidth supplied to the user. Contended services are usually much cheaper to provide than uncontended services, although they only reduce the backbone traffic costs for the users, and do not reduce the costs of providing and maintaining equipment for connecting to the network.

Contents

Examples by country

In the United Kingdom, a Rate Adaptive Digital Subscriber Line (RADSL) connection used to be marketed with a contention ratio between 20:1 and 50:1 within the British Telecom network, meaning that 20 to 50 subscribers, each assigned or sold a bandwidth of up to 8 Mbit/s for instance, may be sharing 8 Mbit/s of downlink bandwidth. [n 1] With the advent of ADSL2+ (up to 20 Mbit/s service, though in theory, ADSL2+ provides up to 24 Mbit/s), FTTC (Fibre to the Cabinet) offering 40 Mbit/s services and even FTTP (Fibre to the Premises) offering 100 Mbit/s, BT no longer work on "contention ratio" as a planning rule.

In the United States and on satellite internet connections, the contention ratio is often higher, and other formulas are used, such as counting only those users who are actually online at a particular time.[ citation needed ] It is also less often divulged by internet service providers elsewhere than it is in the UK.[ citation needed ] The connection speed for each user will therefore differ depending on the number of computers using the uplink connection at the same time because the uplink (where all the low bandwidth connections join) will only handle the speed that has been implemented on that line.

Issues

One of the issues with a stated contention ratio is that it is not, on its own, adequate for comparing services. There is a huge difference between 1000 users each on a 2 Mbit/s service sharing a 40 Mbit/s pipe, and 50 users each on a 2 Mbit/s service sharing a 2 Mbit/s pipe. In the latter case two users trying to download at the same time means each get 50% of the speed. When there are 1000 users it would take 20 users using their entire 2 Mbit/s link at the same time to show any congestion. However, both of these would be quoted as 50:1 contention.

If there are a small number of users of a contended service, then the peaks and troughs in usage will be very visible to each user, but if the same contention ratio applies to a large number of users then the probability of being affected by the contention can be much smaller. In telephony, 20 users each likely to make a call 10% of the time need 8 lines to ensure that there is less than 0.1% chance of being blocked. With 200 users, the number of lines required is only 35, so that less than five times the number of lines are required for the same probability of being blocked. The same issue applies to broadband service.

See also

Notes

  1. An account of the state of the issue in the UK is found in an OFCOM 2004 report on wireless internet. Archived September 30, 2007, at the Wayback Machine

Related Research Articles

Digital subscriber line is a family of technologies that are used to transmit digital data over telephone lines. In telecommunications marketing, the term DSL is widely understood to mean asymmetric digital subscriber line (ADSL), the most commonly installed DSL technology, for Internet access.

<span class="mw-page-title-main">Broadband</span> Data transmission concept

In telecommunications, broadband or high speed is the wide-bandwidth data transmission that exploits signals at a wide spread of frequencies or several different simultaneous frequencies, and is used in fast Internet access. The transmission medium can be coaxial cable, optical fiber, wireless Internet (radio), twisted pair cable, or satellite.

Very high-speed digital subscriber line (VDSL) and very high-speed digital subscriber line 2 (VDSL2) are digital subscriber line (DSL) technologies providing data transmission faster than the earlier standards of asymmetric digital subscriber line (ADSL) G.992.1, G.992.3 (ADSL2) and G.992.5 (ADSL2+).

<span class="mw-page-title-main">Satellite Internet access</span> Satellite-provided Internet

Satellite Internet access is Internet access provided through communication satellites; if it can sustain high speeds, it is termed satellite broadband. Modern consumer grade satellite Internet service is typically provided to individual users through geostationary satellites that can offer relatively high data speeds, with newer satellites using the Ku band to achieve downstream data speeds up to 506 Mbit/s. In addition, new satellite internet constellations are being developed in low-earth orbit to enable low-latency internet access from space.

Telkom SA SOC Limited is a South African wireline and wireless telecommunications provider, operating in more than 38 countries across the African continent. Telkom is majority state-owned (55.3%) with the South African government owning 40.5% of Telkom, while another 14.8% is owned by another state-owned company - the Public Investment Corporation (PIC), which is closely linked to the South African government.

<span class="mw-page-title-main">Internet Protocol television</span> Television transmitted over a computer network

Internet Protocol television (IPTV) is the delivery of television content over Internet Protocol (IP) networks. This is in contrast to delivery through traditional terrestrial, satellite, and cable television formats. Unlike downloaded media, IPTV offers the ability to stream the source media continuously. As a result, a client media player can begin playing the content almost immediately. This is known as streaming media.

Datastream is a type of broadband network connection in the United Kingdom. Datastream is a wholesale product in which the wholesale customer can purchase connectivity between their own point of presence and a number of end users. Some authors use the term "datastream" for replacing the term dataflow to avoid confusion with dataflow computing or dataflow architecture, based on an indeterministic machine paradigm.

<span class="mw-page-title-main">G.992.5</span> ITU-T Recommendation

G.992.5 is an ITU-T standard for asymmetric digital subscriber line (ADSL) broadband Internet access. The standard has a maximum theoretical downstream sync speed of 24 megabits per second (Mbit/s). Utilizing G.992.5 Annex M upstream sync speeds of 3.3 Mbit/s can be achieved.

<span class="mw-page-title-main">Be Un Limited</span> Internet service provider in the UK

Be Unlimited was an Internet service provider in the United Kingdom between 2004 and 2014. Initially founded as an independent company by Boris Ivanovic and Dana Tobak in 2005, it was bought by Spanish group Telefónica Europe in 2006 before being sold on to BSkyB in March 2013 in an agreement which saw BSkyB buy the fixed telephone line and broadband business of Telefónica Europe which at the time traded under the O2 and BE brands. The deal saw BSkyB agree to pay £180 million initially, followed by a further £20 million after all customers had been transferred to Sky's existing business. The sale was subject to regulatory approval in April 2013, and was subsequently approved by the Office of Fair Trading on 16 May 2013.

<span class="mw-page-title-main">Exetel</span> Australian internet service provider

Exetel is an Australian ISP which provides ADSL, web hosting, VoIP, and other internet services to customers across Australia. Exetel's headquarters are in offices in Sydney, and its switching centres are distributed in capital city secure data centre facilities around mainland Australia.

<span class="mw-page-title-main">Virgin Media</span> British television and telecommunications company

Virgin Media is a telecommunications company from England, founded in 2007, which provides telephone, television and internet services in the United Kingdom. Its headquarters are at Green Park in Reading, England. It is owned by Virgin Media O2, a 50:50 joint venture between Liberty Global and Telefónica.

In telecommunications, cable Internet access, shortened to cable Internet, is a form of broadband internet access which uses the same infrastructure as cable television. Like digital subscriber line and fiber to the premises services, cable Internet access provides network edge connectivity from the Internet service provider to an end user. It is integrated into the cable television infrastructure analogously to DSL which uses the existing telephone network. Cable TV networks and telecommunications networks are the two predominant forms of residential Internet access. Recently, both have seen increased competition from fiber deployments, wireless, mobile networks and satellite internet access.

Fiber to the <i>x</i> Broadband network architecture term

Fiber to the x or fiber in the loop is a generic term for any broadband network architecture using optical fiber to provide all or part of the local loop used for last mile telecommunications. As fiber optic cables are able to carry much more data than copper cables, especially over long distances, copper telephone networks built in the 20th century are being replaced by fiber.

<span class="mw-page-title-main">High Speed Packet Access</span> Communications protocols

High Speed Packet Access (HSPA) is an amalgamation of two mobile protocols—High Speed Downlink Packet Access (HSDPA) and High Speed Uplink Packet Access (HSUPA)—that extends and improves the performance of existing 3G mobile telecommunication networks using the WCDMA protocols. A further-improved 3GPP standard called Evolved High Speed Packet Access was released late in 2008, with subsequent worldwide adoption beginning in 2010. The newer standard allows bit rates to reach as high as 337 Mbit/s in the downlink and 34 Mbit/s in the uplink; however, these speeds are rarely achieved in practice.

Internet in Australia first became available on a permanent basis to universities in Australia in May 1989, via AARNet. Pegasus Networks was Australia's first public Internet provider in June 1989. The first commercial dial-up Internet Service Provider (ISP) appeared in capital cities soon after, and by the mid-1990s almost the entire country had a range of choices of dial-up ISPs. Today, Internet access is available through a range of technologies, i.e. hybrid fibre coaxial cable, digital subscriber line (DSL), Integrated Services Digital Network (ISDN) and satellite Internet. In July 2009, the federal government, in partnership with the industrial sector, began rolling out a nationwide fibre-to-the-premises (FTTP) and improved fixed wireless and satellite access through the National Broadband Network. Subsequently, the roll out was downgraded to a Multi-Technology Mix on the promise of it being less expensive and with earlier completion. In October 2020, the federal government announced an upgrade by 2023 of NBN fibre-to-the-node (FTTN) services to FTTP for 2 million households, at a cost of A$3.5 billion.

Internet access is widely available in New Zealand, with 94% of New Zealanders having access to the internet as of January 2021. It first became accessible to university students in the country in 1989. As of June 2018, there are 1,867,000 broadband connections, of which 1,524,000 are residential and 361,000 are business or government.

The prevalent means of connecting to the Internet in Germany is DSL, introduced by Deutsche Telekom in 1999. Other technologies such as Cable, FTTH and FTTB (fiber), Satellite, UMTS/HSDPA (mobile) and LTE are available as alternatives.

<span class="mw-page-title-main">Internet in the United Kingdom</span> Overview of the Internet in the United Kingdom

The United Kingdom has been involved with the Internet throughout its origins and development. The telecommunications infrastructure in the United Kingdom provides Internet access to homes and businesses mainly through fibre, cable, mobile and fixed wireless networks, with the UK's 140-year-old copper network, maintained by Openreach, set to be withdrawn by December 2025.

<span class="mw-page-title-main">Internet in India</span> Overview of the internet in India

Internet in India began in 1986 and was initially available only to the educational and research community. General public access to the internet in India began on 15 August 1995. By 2023, India had more than 900 million Internet users. It is reported that in 2022 an average mobile Internet consumption in India was 19.5 GB per month and the mobile data usage per month rose from 4.5 exabytes in 2018 to 14.4 exabytes in 2022.

<span class="mw-page-title-main">TekSavvy</span>

TekSavvy Solutions Inc. (TSI) is a Canadian residential, business, and wholesale telecommunications company based in Chatham, Ontario. In most of the country, it is a wholesale-network-access-based service provider and voice reseller, connecting its service to existing last mile networks from telecom carriers Bell Canada and Telus Communications, and cable carriers Rogers Communications, Cogeco Cable, Shaw and Vidéotron. However, in parts of rural southwestern Ontario, the service is provided over TekSavvy's own fixed wireless network. Recently they have also rolled out their own fibre optic network in parts of southwestern Ontario.

References

  1. UK OFCOM research report annex on broadband