In computer networking, wire speed or wirespeed refers to the hypothetical peak

physical layer In the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer; The layer most closely associated with the physical connection between devices. This layer may be implemented by a PHY chip. The ...

net bit rate In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction w ...

(useful information rate) of a cable (consisting of fiber-optical wires or copper wires) combined with a certain digital communication device, interface, or port. For example, the wire speed of Fast Ethernet is 100 Mbit/s also known as the ''peak bitrate'', ''connection speed'', ''useful bit rate'', ''information rate'', or

digital bandwidth In computing, bandwidth is the maximum rate of data transfer across a given path. Bandwidth may be characterized as network bandwidth, data bandwidth, or digital bandwidth. This definition of ''bandwidth'' is in contrast to the field of signal p ...

capacity. The wire speed is the data transfer rate that a telecommunications standard provides at a reference point between the

and the data link layer.Atlantic
Encyclopaedia of Information Technology
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Related terms

The wire speed should not be confused with the

line bitrate In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction w ...

, also known as ''gross bit rate'', ''raw bitrate'' or

data signalling rate In telecommunication, data signaling rate (DSR), also known as gross bit rate, is the aggregate rate at which data passes a point in the transmission path of a data transmission system. # The DSR is usually expressed in bits per second. # The d ...

, which is 125 Mbit/s in fast Ethernet. In case there is a physical layer overhead, for example due to line coding or

error-correcting code In computing, telecommunication, information theory, and coding theory, an error correction code, sometimes error correcting code, (ECC) is used for controlling errors in data over unreliable or noisy communication channels. The central idea is ...

s, the line bitrate is higher than the wire speed. 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 Network throughput (or just throughput, when in context) refers to the rate of message delivery over a communication channel, such as Ethernet or packet radio, in a communication network. The data that these messages contain may be delivered ove ...

, which typically is a couple of percent lower than the physical layer net bit rate in wired networks due to data-link-layer protocol overhead, data packet gaps, etc., and much lower in wireless networks.

Communicating "at wire speed"

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., be sufficient. 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 A central processing unit (CPU), also called a central processor, main processor or just processor, is the electronic circuitry that executes instructions comprising a computer program. The CPU performs basic arithmetic, logic, controlling, and ...

limitations,

disk Disk or disc may refer to: * Disk (mathematics), a geometric shape * Disk storage Music * Disc (band), an American experimental music band * ''Disk'' (album), a 1995 EP by Moby Other uses * Disk (functional analysis), a subset of a vector sp ...

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. The term wire speed (or wirespeed) is considered a non-formal language term.

References

{{DEFAULTSORT:Wire Speed Data transmission