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'''Wire speed!''' or '''wirespeed''' is a non-formal language term referring to the hypothetical peak [[data transmission]] [[bit rate]] of a [[cable]] (consisting of fiber-optical wires or [[copper wire]]s) combined with a certain digital communication device/interface/port. The wire speed of [[fast Ethernet]] is 100 Mbps<ref>Robert Breyer, Sean Riley, Switched and fast Ethernet: how it works and how to use it, 1995</ref> also known as the [[physical layer]] [[net bitrate]], ''peak bitrate'', ''connection speed'', ''useful bit rate'', ''information rate'' or [[digital bandwidth]] capacity. The wire speed is the data transfer rate that a telecommunications standard provides at a reference point between the [[physical layer]] and the [[datalink layer]].<ref>Atlantic, [http://books.google.com/books?id=4cKg4B4YgvUC&pg=PA556&dq=%22wire+speed%22+microships&ei=YZRYS53BDYmuzQSm3JGqCQ&hl=sv&cd=1#v=onepage&q=&f=false Encyclopaedia of Information Technology] </ref>.
'''Wire speed''' or '''wirespeed''' is a non-formal language term referring to the hypothetical peak [[data transmission]] [[bit rate]] of a [[cable]] (consisting of fiber-optical wires or [[copper wire]]s) combined with a certain digital communication device/interface/port. The wire speed of [[fast Ethernet]] is 100 Mbps<ref>Robert Breyer, Sean Riley, Switched and fast Ethernet: how it works and how to use it, 1995</ref> also known as the [[physical layer]] [[net bitrate]], ''peak bitrate'', ''connection speed'', ''useful bit rate'', ''information rate'' or [[digital bandwidth]] capacity. The wire speed is the data transfer rate that a telecommunications standard provides at a reference point between the [[physical layer]] and the [[datalink layer]].<ref>Atlantic, [http://books.google.com/books?id=4cKg4B4YgvUC&pg=PA556&dq=%22wire+speed%22+microships&ei=YZRYS53BDYmuzQSm3JGqCQ&hl=sv&cd=1#v=onepage&q=&f=false Encyclopaedia of Information Technology] </ref>.


The wire speed should not be confused with the [[line bitrate]], also known as ''gross bit rate'', ''raw bitrate'' or [[data signalling rate]], which is 125 Mbps in fast Ethernet. In case there is a physical layer overhead, for example due to [[line coding]] or [[error-correcting code]]s, the line bitrate is higher than the wire speed.
The wire speed should not be confused with the [[line bitrate]], also known as ''gross bit rate'', ''raw bitrate'' or [[data signalling rate]], which is 125 Mbps in fast Ethernet. In case there is a physical layer overhead, for example due to [[line coding]] or [[error-correcting code]]s, the line bitrate is higher than the wire speed.

Revision as of 09:35, 22 April 2010

Wire speed or wirespeed is a non-formal language term referring to the hypothetical peak data transmission bit rate of a cable (consisting of fiber-optical wires or copper wires) combined with a certain digital communication device/interface/port. The wire speed of fast Ethernet is 100 Mbps[1] also known as the physical layer net bitrate, peak bitrate, connection speed, useful bit rate, information rate or digital bandwidth capacity. The wire speed is the data transfer rate that a telecommunications standard provides at a reference point between the physical layer and the datalink layer.[2].

The wire speed should not be confused with the line bitrate, also known as gross bit rate, raw bitrate or data signalling rate, which is 125 Mbps in fast Ethernet. In case there is a physical layer overhead, for example due to line coding or error-correcting codes, the line bitrate is higher than the wire speed.

Note also that the theoretical channel capacity of the cable may be much higher, especially if the cable is short, but this is not utilized in the communication standard. The channel capacity depends on the physical and electrical properties of the cable, while the wire speed also depends on the connection protocols.

The wire speed may also refer to maximum throughput, which is a couple of percent lower than the physical layer net bitrate in Ethernet due to datalink layer protocol overhead, data packet gaps, etc, and much lower in wireless networks.

The term at wire speed, or the adjective wire speed, describes any computer system or hardware device that is able to achieve a throughput equal to the maximum throughput of the communication standard. This requires that the CPU capacity, bus capacity, network switching capacity, etc, is sufficient. It is common to refer to functions embedded in microchips as working at wire speed, especially when compared to those implemented in software.[clarification needed] Network switches, routers, and similar devices are sometimes described as operating at wire speed. Data encryption and decryption and hardware emulation are software functions that might run at wire speed (or close to it) when embedded in a microchip.

The wire speed is rarely achieved in connections between computers due to CPU limitations, disk read/write overhead, or contention for resources. However, it is still a useful concept for estimating the theoretical best throughput, and how far the real-life performance falls short of the maximum.

References

  1. ^ Robert Breyer, Sean Riley, Switched and fast Ethernet: how it works and how to use it, 1995
  2. ^ Atlantic, Encyclopaedia of Information Technology

For the corporation WireSpeed see WireSpeed Telecommunications