Wire speed
Encyclopedia
Wire speed or wirespeed is a non-formal language term referring to the hypothetical peak physical layer
net bitrate (useful information 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 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 physical layer
and the datalink layer..
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 typically is a couple of percent lower than the physical layer net bitrate in wired networks due to datalink layer protocol overhead, data packet gaps, etc., and much lower in wireless networks.
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
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.
Physical layer
The physical layer or layer 1 is the first and lowest layer in the seven-layer OSI model of computer networking. The implementation of this layer is often termed PHY....
net bitrate (useful information rate) of a cable
Cable
A cable is two or more wires running side by side and bonded, twisted or braided together to form a single assembly. In mechanics cables, otherwise known as wire ropes, are used for lifting, hauling and towing or conveying force through tension. In electrical engineering cables are used to carry...
(consisting of fiber-optical wires or copper wires) combined with a certain digital communication device/interface/port. The wire speed of fast Ethernet
Fast Ethernet
In computer networking, Fast Ethernet is a collective term for a number of Ethernet standards that carry traffic at the nominal rate of 100 Mbit/s, against the original Ethernet speed of 10 Mbit/s. Of the fast Ethernet standards 100BASE-TX is by far the most common and is supported by the...
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 physical layer
Physical layer
The physical layer or layer 1 is the first and lowest layer in the seven-layer OSI model of computer networking. The implementation of this layer is often termed PHY....
and the datalink layer..
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, 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 codes, the line bitrate is higher than the wire speed.Note also that the theoretical channel capacity
Channel capacity
In electrical engineering, computer science and information theory, channel capacity is the tightest upper bound on the amount of information that can be reliably transmitted over a communications channel...
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 typically is a couple of percent lower than the physical layer net bitrate in wired networks due to datalink 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., are sufficient. Network switchNetwork switch
A network switch or switching hub is a computer networking device that connects network segments.The term commonly refers to a multi-port network bridge that processes and routes data at the data link layer of the OSI model...
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
Central processing unit
The central processing unit is the portion of a computer system that carries out the instructions of a computer program, to perform the basic arithmetical, logical, and input/output operations of the system. The CPU plays a role somewhat analogous to the brain in the computer. The term has been in...
limitations, disk
Disk storage
Disk storage or disc storage is a general category of storage mechanisms, in which data are digitally recorded by various electronic, magnetic, optical, or mechanical methods on a surface layer deposited of one or more planar, round and rotating disks...
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.