Bandwidth (computing): Difference between revisions

Revision as of 23:48, 3 December 2023

Revision as of 23:48, 3 December 2023

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The ''consumed bandwidth'' in bit/s, corresponds to achieved [[throughput]] or [[goodput]], i.e., the average rate of successful data transfer through a communication path. The consumed bandwidth can be affected by technologies 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.

''Channel bandwidth'' may be confused with useful data throughput (or goodput). For example, a channel with ''x'' bit/s may not necessarily transmit data at ''x'' rate, since protocols, encryption, and other factors can add appreciable overhead. For instance, much internet traffic uses the [[transmission control protocol]] (TCP), which requires a three-way handshake for each transaction. Although in many modern implementations the protocol is efficient, it does add significant overhead compared to simpler protocols. Also, data packets may be lost, which further reduces the useful data throughput. In general, for any effective digital communication, a framing protocol is needed; overhead and effective throughput depends on implementation. Useful throughput is less than or equal to the actual channel capacity minus implementation overhead.aja

==Maximum throughput==

* The [[asymptotic bandwidth]] (formally ''asymptotic throughput'') for a network is the measure of maximum throughput for a [[greedy source]], for example when the message size (the number of packets per second from a source) approaches close to the maximum amount.<ref>{{cite book |chapter=Modeling Message Passing Overhead |first=C. Y. |last=Chou |year=2006 |title=Advances in Grid and Pervasive Computing: First International Conference, GPC 2006 |editor1-first=Yeh-Ching |editor1-last=Chung |editor2-first=José E. |editor2-last=Moreira |isbn=3540338098 |pages=299–307 |publisher=Springer |display-authors=etal}}</ref>

Asymptotic bandwidths are usually estimated by sending a number of very large messages through the network, measuring the end-to-end throughput. As with other bandwidths, the asymptotic bandwidth is measured in multiples of bits per seconds. Since bandwidth spikes can skew the measurement, carriers often use the 95th [[percentile]] method. This method continuously measures bandwidth usage and then removes the top 5 percent.<ref>{{Cite web|url=https://www.paessler.com/it-explained/bandwidth|title=What is Bandwidth? - Definition and Details|website=www.paessler.com|language=en|access-date=2019-04-18}}</ref>