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 100 megabit Ethernet standards 100baseTX is by far the most common and is supported by the vast majority of Ethernet hardware currently produced. Full duplex fast Ethernet is sometimes referred to as "200 Mbit/s" though this is somewhat misleading as that level of improvement will only be achieved if traffic patterns are symmetrical. Fast Ethernet was introduced in 1995^[1] and remained the fastest version of Ethernet for three years before being superseded by gigabit Ethernet.^[2] Computer networks redirects here. ... Ethernet is a large, diverse family of frame-based computer networking technologies that operates at many speeds for local area networks (LANs). ... Gigabit Ethernet (GbE) is a term describing various technologies for transmitting Ethernet packets at a rate of a gigabit per second, as defined by the IEEE 802. ...

A fast Ethernet adaptor can be logically divided into a medium access controller (MAC) which deals with the higher level issues of medium availiblity and a physical layer interface (PHY). The MAC may be linked to the PHY by a 4 bit 25 MHz synchronous parallel interface known as MII. Repeaters (hubs) are also allowed and connect to multiple PHYs for their different interfaces. MAC or Medium Access Controller is the hardware or rarely software which provides data link layer connectivity for local area network protocols, most commonly Ethernet. ... The Media Independent Interface (MII) is a chip commonly found on Ethernet devices, together with the PHY. The standard MII features a small set of registers: Basic Mode Configuration (#0) Status Word (#1) PHY Identification (#2, #3) Ability Advertisement (#4) Link Partner Ability (#5) Auto Negotiation Expansion (#6) The MII...

The MII interface may (rarely) be an external connection but is usually a connection between ICs in a network adaptor or even within a single IC. The specs are written based on the assumption that the interface between MAC and PHY will be MII but they do not require it.

The MII interface fixes the theoretical maximum data bit rate for all versions of fast Ethernet to 100 Mbit/s. The data signaling rate actually observed on real networks is less than the theoretical maximum, due to the necessary header and trailer (addressing and error-detection bits) on every packet, the occasional "lost packet" due to noise, and time waiting after each sent packet for other devices on the network to finish transmitting. In telecommunication, data signaling rate (DSR) is the aggregate rate at which data pass a point in the transmission path of a data transmission system. ...

Copper

3Com 3c905-TX 100BASE-TX PCI network interface card

100BASE-T is any of several Fast Ethernet standards for twisted pair cables, including: 100BASE-TX (100 Mbit/s over two-pair Cat5 or better cable), 100BASE-T4 (100 Mbit/s over four-pair Cat3 or better cable, defunct), 100BASE-T2 (100 Mbit/s over two-pair Cat3 or better cable, also defunct). The segment length for a 100BASE-T cable is limited to 100 metres (328 ft) (as with 10BASE-T and gigabit Ethernet). All are or were standards under IEEE 802.3 (approved 1995). Image File history File linksMetadata Size of this preview: 752 × 599 pixels Full resolution (1247 × 994 pixel, file size: 306 KB, MIME type: image/jpeg) (All user names refer to en. ... Image File history File linksMetadata Size of this preview: 752 × 599 pixels Full resolution (1247 × 994 pixel, file size: 306 KB, MIME type: image/jpeg) (All user names refer to en. ... This article or section does not cite its references or sources. ... 25 Pair Color Code Chart 10BASE-T UTP Cable Twisted pair cabling is a common form of wiring in which two conductors are wound around each other for the purposes of cancelling out electromagnetic interference known as crosstalk. ... Cat5 patch cable Category 5 cable, commonly known as Cat 5, is a twisted pair cable type designed for high signal integrity. ... Category 3 cable, commonly known as Cat 3, is an unshielded twisted pair (UTP) cable designed to reliably carry data up to 10 Mbit/s, with a possible bandwidth of 16 MHz. ... The or meter (see spelling differences) is a measure of length. ... A foot (plural: feet or foot;[1] symbol or abbreviation: ft or, sometimes, ′ – a prime) is a unit of length, in a number of different systems, including English units, Imperial units, and United States customary units. ... 10BASE-T cable 10BASE-T plug 10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. ... Gigabit Ethernet (GbE) is a term describing various technologies for transmitting Ethernet packets at a rate of a gigabit per second, as defined by the IEEE 802. ... IEEE 802. ...

In the early days of Fast Ethernet, much vendor advertising centered on claims by competing standards that "ours will work better with existing cables than theirs." In practice, it was quickly discovered that few existing networks actually met the assumed standards, because 10-megabit Ethernet was very tolerant of minor deviations from specified electrical characteristics and few installers ever bothered to make exact measurements of cable and connection quality: if Ethernet worked over a cable, it was deemed acceptable. Thus most networks had to be rewired for 100-megabit speed whether or not they had supposedly been CAT3 or CAT5 cable plants. The vast majority of common implementations or installations of 100BASE-T are done with 100BASE-TX.

100BASE-TX

RJ-45 Wiring (TIA/EIA-568-B T568B)

Pin	Pair	Wire	Color
1	2	1	white/orange
2	2	2	orange
3	3	1	white/green
4	1	2	blue
5	1	1	white/blue
6	3	2	green
7	4	1	white/brown
8	4	2	brown

100BASE-TX is the predominant form of Fast Ethernet, and runs over two pairs of category 5 or above cable (a typical category 5 cable contains 4 pairs and can therefore support two 100BASE-TX links). Like 10BASE-T, the proper pairs are the orange and green pairs (canonical second and third pairs) in TIA/EIA-568-B's termination standards, T568A or T568B. These pairs use pins 1, 2, 3 and 6. Cat5 cables with RJ-45 connectors, wired to EIA/TIA-568B An RJ-45 connector that has yet to be crimped onto a cable RJ-45 (Registered Jack 45) is a physical interface often used for terminating twisted pair type cables. ... Cat5 cables with RJ45 connectors wired to T568B TIA/EIA-568-B is a set of three standards that address commercial building cabling for telecommunications products and services (the three standards are formally titled ANSI/TIA/EIA-568-B.1-2001, -B.2-2001, and -B.3-2001). ... Image File history File links Wire_white_orange_stripe. ... Image File history File links Wire_orange. ... Image File history File links Wire_white_green_stripe. ... Image File history File links Wire_blue. ... Image File history File links Wire_white_blue_stripe. ... Image File history File links Wire_green. ... Image File history File links Wire_white_brown_stripe. ... Image File history File links Wire_brown. ... Category 5 can refer to either: Category 5 cable used for carrying data Category 5 computer virus as classified by Symantec Corporation for the most severe threat level. ... 10BASE-T cable 10BASE-T plug 10BASE-T is an implementation of Ethernet which allows stations to be attached via twisted pair cable. ... Canonical is an adjective derived from canon. ... Cat5 cables with RJ45 connectors wired to T568B TIA/EIA-568-B is a set of three standards that address commercial building cabling for telecommunications products and services (the three standards are formally titled ANSI/TIA/EIA-568-B.1-2001, -B.2-2001, and -B.3-2001). ...

In T568A and T568B, wires are in the order 1, 2, 3, 6, 4, 5, 7, 8 on the modular jack at each end. The colour-order would be green/white, green, orange/white, blue, blue/white, orange, brown/white, brown for T568A, and orange/white, orange, green/white, blue, blue/white, green, brown/white, brown for T568B.

Each network segment can have a maximum distance of 100 metres (330 ft). In its typical configuration, 100BASE-TX uses one pair of twisted wires in each direction, providing 100 Mbit/s of throughput in each direction (full-duplex). See IEEE 802.3 for more details. A network segment is a portion of a computer network wherein every device communicates using the same physical layer. ... In telecommunications, duplex means two-way when referring to communications channels. ... IEEE 802. ...

The configuration of 100BASE-TX networks is very similar to 10BASE-T. When used to build a local area network, the devices on the network (computers, printers etc.) are typically connected to a hub or switch, creating a star network. Alternatively it is possible to connect two devices directly using a crossover cable. Local area network scheme A local area network is a computer network covering a small geographic area, like a home, office, or group of buildings. ... 4 port ethernet hub An Ethernet hub or concentrator is a device for connecting multiple twisted pair or fiber optic Ethernet devices together, making them act as a single segment. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... Star network layout Star networks are one of the most common computer network topologies. ... Crossover cable suitable for use with 100BASE-T4 Fast Ethernet 8P8C modular crossover adapter Compare crossover cable pinout with standard pinout. ...

With 100BASE-TX hardware, the raw bits go through 4B5B binary encoding to generate a series of 0 and 1 bits clocked at 125 MHz; the 4B5B encoding provides DC equalization and spectrum shaping (see the standard for details). Just as in the 100BASE-FX case, the bits are then transferred to the physical medium attachment layer using NRZI encoding. However, 100BASE-TX introduces an additional, medium dependent sublayer, which employs MLT-3 as a final encoding of the data stream before transmission. The procedure is borrowed from the ANSI X3.263 FDDI specifications, with minor discrepancies.^[3] In telecommunication, 4B5B is a form of data communications line code. ... Categories: Stub ... MLT-3 (Multilevel Transmission Encoding - 3 levels) Encoding that is used in 100-Base-TX Ethernet. ... In computer networking, fiber-distributed data interface (FDDI) is a standard for data transmission in a local area network that can extend in range up to 200 km (124 miles). ...

100BASE-T4

100BASE-T4 was an early implementation of Fast Ethernet. It requires four twisted copper pairs, but those pairs were only required to be category 3 rather than the category 5 required by TX. One pair is reserved for transmit, one for receive, and the remaining two will switch direction as negotiated. A very unusual 8B6T code is used to convert 8 data bits into 6 base-3 digits (the signal shaping is possible as there are three times as many 6-digit base-3 numbers as there are 8-digit base-2 numbers). The two resulting 3-digit base-3 symbols are sent in parallel over 3 pairs using 3-level pulse-amplitude modulation (PAM-3). Pulse-amplitude modulation, acronym PAM, is a form of signal modulation where the message information is encoded in the amplitude of a series of signal pulses. ...

100BASE-T2

In 100BASE-T2, the data is transmitted over two copper pairs, 4 bits per symbol. First, a 4 bit symbol is expanded into two 3-bit symbols through a non-trivial scrambling procedure based on a linear feedback shift register; see the standard for details. This is needed to flatten the bandwidth and emission spectrum of the signal, as well as to match transmission line properties. The mapping of the original bits to the symbol codes is not constant in time and has a fairly large period (appearing as a pseudo-random sequence). The final mapping from symbols to PAM-5 line modulation levels obeys the table on the right. A linear feedback shift register (LFSR) is a shift register whose input bit is a linear function of its previous state. ...

Fiber

100BASE-FX

100BASE-FX is a version of Fast Ethernet over optical fiber. It uses two strands of multi-mode optical fiber for receive(RX) and transmit(TX). Maximum length is 400 metres (1,310 ft) for half-duplex connections (to ensure collisions are detected) or 2 kilometres (6,600 ft) for full-duplex. 100BASE-FX uses the same 4B5B encoding and NRZI line code that 100BASE-TX does. 100BASE-FX should use SC, ST, or MIC connectors with SC being the preferred option.^[4] Optical fibers An optical fiber (or fibre) is a glass or plastic fiber designed to guide light along its length by confining as much light as possible in a propagating form. ... Multi-mode optical fiber (multimode fiber or MM fiber) is a type of optical fiber mostly used for communication over shorter distances, e. ... In telecommunications, duplex means two-way when referring to communications channels. ... For other uses, see Collision (disambiguation). ...

100BASE-FX is not compatible with 10BASE-FL, the 10 MBit/s version over optical fiber. It uses a 1300 nm near-infrared (NIR) light wavelength. 10BASE-FL is the most commonly used 10BASE-F specification of Ethernet over optical fiber. ... A nanometre (American spelling: nanometer, symbol nm) is a unit of length in the metric system, equal to one thousand-millionth of a metre, which is the current SI base unit of length. ... Image of two girls in mid-infrared (thermal) light (false-color) Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. ... The wavelength is the distance between repeating units of a wave pattern. ...

100BASE-SX

100BASE-SX is a version of Fast Ethernet over optical fiber. It uses two strands of multi-mode optical fiber for receive and transmit. It is a lower cost alternative to using 100BASE-FX, because it uses short wavelength optics which are significantly less expensive than the long wavelength optics used in 100BASE-FX. 100BASE-SX can operate at distances up to 300 metres (980 ft).

100BASE-SX uses the same wavelength as 10BASE-FL, the 10 MBit/s version over optical fiber. Unlike 100BASE-FX, this allows 100BASE-SX to be backwards-compatible with 10BASE-FL.

Because of the shorter wavelength used (850 nm) and the shorter distance it can support, 100BASE-SX uses less expensive optical components (LEDs instead of lasers) which makes it an attractive option for those upgrading from 10BASE-FL and those who do not require long distances.

100BASE-BX

100BASE-BX is a version of Fast Ethernet over a single strand of optical fiber (unlike 100BASE-FX, which uses a pair of fibers). Single-mode fiber is used, along with a special multiplexer which splits the signal into transmit and receive wavelengths.

See also

• IEEE 802.3
• Gigabit Ethernet
• 10 gigabit Ethernet
• 100 gigabit Ethernet

IEEE 802. ... Gigabit Ethernet (GbE) is a term describing various technologies for transmitting Ethernet packets at a rate of a gigabit per second, as defined by the IEEE 802. ... 10 gigabit Ethernet or 10GbE is the most recent (as of 2006) and fastest of the Ethernet standards. ... 100 gigabit Ethernet or 100GbE is an Ethernet standard presently under early development by the IEEE. The fastest existing standard is 10 gigabit Ethernet. ...

References

1. ^ IEEE 802.3u-1995
2. ^ The 802.3z Gigabit Ethernet Standard was published in July 1998.
3. ^ "The 100BASE-TX PMD (and MDI) is specified by incorporating the FDDI TP-PMD standard, ANSI X3.263: 1995 (TP-PMD), by reference, with the modifications noted below." (section 25.2 of IEEE802.3-2002).
4. ^ 802.3-2005 section 26.4.1

This article was originally based on material from the Free On-line Dictionary of Computing, which is licensed under the GFDL. The Free On-line Dictionary of Computing (FOLDOC) is an online, searchable encyclopedic dictionary of computing subjects. ... Bold text // “GFDL” redirects here. ...

External links

• Common 100 Mbit/s Hardware Variations
• Origins and History of Ethernet
• 100BASE-SX Fast Ethernet proposal