computer networking A computer network is a collection of communicating computers and other devices, such as printers and smart phones. In order to communicate, the computers and devices must be connected by wired media like copper cables, optical fibers, or b ...

, 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. The physical layer provides an electrical, mechani ...

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 ...

(useful information rate) of a

cable Cable may refer to: Mechanical * Nautical cable, an assembly of three or more ropes woven against the weave of the ropes, rendering it virtually waterproof * Wire rope, a type of rope that consists of several strands of metal wire laid into a hel ...

(consisting of fiber-optical wires or

copper wire Copper has been used in electrical wiring since the invention of the electromagnet and the telegraph in the 1820s. The invention of the telephone in 1876 created further demand for copper wire as an electrical conductor. Copper is the electri ...

s) combined with a certain digital communication device, interface, or port. For example, the wire speed of

Fast Ethernet In computer networking, Fast Ethernet Ethernet physical layer, physical layers carry traffic at the nominal rate of . The Classic Ethernet, prior Ethernet speed was . Of the Fast Ethernet physical layers, 100BASE-TX is by far the most common. ...

is 100 Mbit/s also known as the ''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

and the

data link layer The data link layer, or layer 2, is the second layer of the seven-layer OSI model of computer networking. This layer is the protocol layer that transfers data between nodes on a network segment across the physical layer. The data link layer p ...

.Atlantic
Encyclopaedia of Information Technology
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Related terms

The wire speed should not be confused with the line bitrate, also known as ''gross bit rate'', ''raw bitrate'' or

data signalling rate In telecommunications, 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. Properties # The DSR is usually expressed in bits per s ...

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

line coding In telecommunications, a line code is a pattern of voltage, current, or photons used to represent digital data transmitted down a communication channel or written to a storage medium. This repertoire of signals is usually called a constrained ...

error-correcting code In computing, telecommunication, information theory, and coding theory, forward error correction (FEC) or channel coding is a technique used for controlling errors in data transmission over unreliable or noisy communication channels. The centra ...

s, the line bitrate is higher than the wire speed. The theoretical

channel capacity Channel capacity, in electrical engineering, computer science, and information theory, is the theoretical maximum rate at which information can be reliably transmitted over a communication channel. Following the terms of the noisy-channel coding ...

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 Protocol may refer to: Sociology and politics * Protocol (politics), a formal agreement between nation states * Protocol (diplomacy), the etiquette of diplomacy and affairs of state * Etiquette, a code of personal behavior Science and technology ...

. 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 in a communication network, such as Ethernet or packet radio. 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 switch A network switch (also called switching hub, bridging hub, Ethernet switch, and, by the IEEE, MAC bridge) is networking hardware that connects devices on a computer network by using packet switching to receive and forward data to the destinat ...

es, 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 primary processor in a given computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, log ...

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

References

{{DEFAULTSORT:Wire Speed Data transmission