Bandwidth (computing)
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Look up Bandwidth in Wiktionary, the free dictionary. |
In computer networking and computer science, bandwidth[1], network bandwidth[2], data bandwidth[3] or digital bandwidth[4][5] is a bit rate measure of available or consumed data communication resources expressed in bits/second or multiples of it (kilobits/s, megabits/s etc.).
Note that in textbooks on data transmission, digital communications, wireless communications, electronics, etc., bandwidth refers to analog signal bandwidth measured in hertz - the original meaning of the term. Some computer networking authors prefer less ambiguous terms such as bit rate, channel capacity and throughput rather than bandwidth in bit/s, to avoid this confusion.
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[edit] Network bandwidth capacity
In computer networking, bandwidth in bit/s sometimes means the net bit rate (also known as peak bit rate, information rate or physical layer useful bit rate), channel capacity, or the maximum throughput of a logical or physical communication path in a digital communication system. For example, bandwidth tests measure the maximum throughput of a computer network. The reason for this usage is that according to Hartley's law, the maximum data rate of a physical communication link is proportional to its bandwidth in hertz, which is sometimes called frequency bandwidth, spectral bandwidth, RF bandwidth, signal bandwidth or analog bandwidth.
[edit] Network bandwidth consumption
In computer networking, bandwidth in bit/s may also refer to consumed bandwidth, corresponding to achieved throughput or goodput, i.e., the average rate of successful data transfer through a communication path. This sense applies to expressions such as bandwidth shaping, bandwidth management, bandwidth throttling, bandwidth cap, bandwidth allocation (for example bandwidth allocation protocol and dynamic bandwidth allocation), etc. A bit stream's bandwidth is proportional to the average consumed signal bandwidth in Hertz (the average spectral bandwidth of the analog signal representing the bit stream) during a studied time interval.
[edit] Multimedia bandwidth
Digital bandwidth may also refer to: multimedia bit rate or average bitrate after multimedia data compression (source coding), defined as the total amount of data divided by the playback time.
[edit] Bandwidth in web hosting
In website hosting, the term "bandwidth" is often incorrectly used to describe the amount of data transferred to or from the website or server within a prescribed period of time, for example bandwidth consumption accumulated over a month measured in gigabytes per month. The more accurate phrase used for this meaning of a maximum amount of data transfer each month or given period is monthly data transfer..
[edit] Internet connection bandwidths
This table shows the maximum bandwidth (the physical layer net bitrate) of common Internet access technologies. For a more detailed list see list of device bandwidths, bit rate progress trends and list of bitrates in multimedia.
| 56 kbit/s | Modem / Dialup |
| 1.5 Mbit/s | ADSL Lite |
| 1.544 Mbit/s | T1/DS1 |
| 10 Mbit/s | Ethernet |
| 11 Mbit/s | Wireless 802.11b |
| 44.736 Mbit/s | T3/DS3 |
| 54 Mbit/s | Wireless 802.11g |
| 100 Mbit/s | Fast Ethernet |
| 155 Mbit/s | OC3 |
| 600 Mbit/s | Wireless 802.11n |
| 622 Mbit/s | OC12 |
| 1 Gbit/s | Gigabit Ethernet |
| 2.5 Gbit/s | OC48 |
| 9.6 Gbit/s | OC192 |
| 10 Gbit/s | 10 Gigabit Ethernet |
| 100 Gbit/s | 100 Gigabit Ethernet |
[edit] See also
[edit] References
- ^ Andrew S. Tanenbaum Computer networks, Prentice Hall PTR, 2003
- ^ Douglas Comer, Computer Networks and Internets , page 99 ff, Prentice Hall 2008.
- ^ Fred Halsall, Introduction to data communications and computer networks, page 108, Addison-Wesley, 1985.
- ^ Cisco Networking Academy Program: CCNA 1 and 2 companion guide, Volym 1–2, Cisco Academy 2003
- ^ Behrouz A. Forouzan, Data communications and networking, McGraw-Hill, 2007
