View source for Fast Ethernet

{{Short description|Ethernet standards that carry data at the nominal rate of 100 Mbit/s}}
{{Use American English|date=February 2022}}

[[File:Intel Pro-100 82558 PCI NIC.jpg|thumb|[[Intel]] PRO/100 Fast Ethernet [[Network interface controller|NIC]], a PCI card]]

In [[computer network]]ing, '''Fast Ethernet''' [[Ethernet physical layer|physical layers]] carry traffic at the nominal rate of {{nowrap|100 Mbit/s}}. The [[Classic Ethernet|prior Ethernet]] speed was {{nowrap|10 Mbit/s}}. Of the Fast Ethernet physical layers, '''100BASE-TX''' is by far the most common.

Fast Ethernet was introduced in 1995 as the '''IEEE 802.3u''' standard<ref>{{cite book| doi = 10.1109/IEEESTD.1995.7974916|title=IEEE 802.3u-1995|date=October 26, 1995|publisher=[[IEEE]]|isbn=978-0-7381-0276-4}}</ref> and remained the fastest version of Ethernet for three years before the introduction of [[Gigabit Ethernet]].<ref>{{cite journal |author=H. Frazier |orig-year=1998 |year=2002 |title=The 802.3z Gigabit Ethernet Standard |journal=IEEE Network |publisher=IEEE |volume=12 |issue=3 |pages=6–7 |doi=10.1109/65.690946 }}</ref> The acronym ''GE/FE'' is sometimes used for devices supporting both standards.<ref>{{cite web|url=https://www.juniper.net/techpubs/hardware/erx/junose103/hw-erx-module/oc3-ge-fe-w-aps.html|title=OC3/STM1 GE/FE Module Combination - ERX 10.3.x Module Guide|publisher=[[Juniper Networks]]}}</ref>

== Nomenclature ==
The ''100'' in the media type designation refers to the transmission speed of {{nowrap|100 Mbit/s}}, while the ''BASE'' refers to [[baseband]] signaling. The letter following the dash (''T'' or ''F'') refers to the physical medium that carries the signal (twisted pair or fiber, respectively), while the last character (''X'', ''4'', etc.) refers to the [[line code]] method used. Fast Ethernet is sometimes referred to as '''100BASE-X''', where ''X'' is a placeholder for the FX and TX variants.<ref>{{Cite web|url=http://www.cisco.com/c/en/us/products/collateral/interfaces-modules/fast-ethernet-sfp-modules/product_data_sheet0900aecd801f931c.html |title=Cisco 100BASE-X Small Form-Factor Pluggable Modules for Fast Ethernet Applications Data Sheet |publisher=Cisco}}</ref>

== General design ==
Fast Ethernet is an extension of the 10-megabit [[Ethernet]] standard. It runs on [[twisted pair]] or [[optical fiber cable]] in a [[Star topology|star wired bus topology]], similar to the IEEE standard 802.3i called [[10BASE-T]], itself an evolution of 10BASE5 (802.3) and 10BASE2 (802.3a). Fast Ethernet devices are generally backward compatible with existing 10BASE-T systems, enabling plug-and-play upgrades from 10BASE-T. Most switches and other networking devices with ports capable of Fast Ethernet can perform [[autonegotiation]], sensing a piece of 10BASE-T equipment and setting the port to 10BASE-T half duplex if the 10BASE-T equipment cannot perform autonegotiation itself. The standard specifies the use of [[CSMA/CD]] for media access control. A [[full-duplex]] mode is also specified and in practice, modern networks use [[Ethernet switch]]es and operate in full-duplex mode, even as legacy devices that use half duplex still exist.

A Fast Ethernet adapter can be logically divided into a [[media access control]]ler (MAC), which deals with the higher-level issues of medium availability, and a physical layer interface ([[PHY]]). The MAC is typically linked to the PHY by a four-bit 25&nbsp;MHz synchronous parallel interface known as a [[media-independent interface]] (MII), or by a two-bit 50&nbsp;MHz variant called [[reduced media independent interface]] (RMII). In rare cases, the MII may be an external connection but is usually a connection between ICs in a network adapter or even two sections within a single IC. The specs are written based on the assumption that the interface between MAC and PHY will be an MII but they do not require it. Fast Ethernet or [[Ethernet hub]]s may use the MII to connect to multiple PHYs for their different interfaces.

The MII fixes the theoretical maximum data bit rate for all versions of Fast Ethernet to {{nowrap|100 Mbit/s}}. The [[information 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 [[Ethernet frame]], and the required [[interpacket gap]] between transmissions.

== Copper ==
'''100BASE-T''' is any of several Fast Ethernet standards for [[twisted pair cable]]s,{{dubious|Semantics of 100BASE-T|date=October 2021}} including: 100BASE-TX ({{nowrap|100 Mbit/s}} over two-pair [[Category 5 cable|Cat5]] or better cable), 100BASE-T4 (100&nbsp;Mbit/s over four-pair [[Category 3 cable|Cat3]] or better cable, defunct), 100BASE-T2 ({{nowrap|100 Mbit/s}} over two-pair Cat3 or better cable, also defunct). The segment length for a 100BASE-T cable is limited to {{convert|100|m|ft|0}} (the same limit as [[10BASE-T]] and [[gigabit Ethernet]]). All are or were standards under [[IEEE 802.3]] (approved 1995). Almost all 100BASE-T installations are 100BASE-TX.

{| class="wikitable" style="line-height:110%;"
|+Comparison of [[Ethernet over twisted pair|twisted-pair-based Ethernet]] physical transport layers (TP-PHYs)<ref name="TDG_ETH_2nd">{{cite book |title=Ethernet: The Definitive Guide |edition=2nd |author=Charles E. Spurgeon |publisher=O'Reilly Media |year=2014 |isbn=978-1-4493-6184-6}}</ref>
! Name
! Standard
! Status
! Speed {{nowrap|(Mbit/s)}}
! Pairs required
! Lanes per direction
! Bits per hertz
! [[Line code]]
! [[Symbol rate]] per lane (MBd) 
! Bandwidth (MHz)
! Max distance (m)
! Cable
! Cable rating (MHz)
! Usage
|-
| {{nowrap|[[100BASE-TX]]}}
| {{nowrap|802.3u-1995}}
| {{active|current}}
| align="right" | 100
| align="right" | 2
| align="right" | 1
| align="right" | 3.2
| align="right" | [[4B5B]] [[MLT-3]] [[NRZI]]
| align="right" | 125
| align="right" | 31.25
| align="right" | 100
| align="center" | [[Category 5 cable|Cat&nbsp;5]]
| align="right" | 100
| align="center" | LAN
|-
| {{nowrap|[[100BASE-T1]]}}
| {{nowrap|802.3bw-2015}} (CL96)
| {{active|current}}
| align="right" | 100
| align="right" | 1
| align="right" | 1
| align="right" | 2.6{{overline|6}}
| align="right" | PAM-3 4B/3B
| align="right" | 75
| align="right" | 37.5
| align="right" | 15
| align="center" | [[Category 5e cable|Cat&nbsp;5e]]
| align="right" | 66
| align="center" | Automotive, IoT, M2M
|-
| {{nowrap|[[100BASE-T2]]}}
| {{nowrap|802.3y-1997}}
| {{N/A|obsolete}}
| align="right" | 100
| align="right" | 2
| align="right" | 2
| align="right" | 4
| align="right" | LFSR PAM-5
| align="right" | 25
| align="right" | 12.5
| align="right" | 100
| align="center" | [[Category 3 cable|Cat&nbsp;3]]
| align="right" | 16
| {{N/A|''Market failure''}}
|-
| {{nowrap|[[100BASE-T4]]}}
| {{nowrap|802.3u-1995}}
| {{N/A|obsolete}}
| align="right" | 100
| align="right" | 4
| align="right" | 3
| align="right" | 2.6{{overline|6}}
| align="right" | 8B6T PAM-3 ''Half-duplex only''
| align="right" | 25
| align="right" | 12.5
| align="right" | 100
| align="center" | [[Category 3 cable|Cat&nbsp;3]]
| align="right" | 16
| {{N/A|''Market failure''}}
|-
| {{nowrap|[[100BaseVG]]}}
| {{nowrap|802.12-1995}}
| {{N/A|obsolete}}
| align="right" | 100
| align="right" | 4
| align="right" | 4
| align="right" | 1.6{{overline|6}}
| align="right" | 5B6B ''Half-duplex only''
| align="right" | 30
| align="right" | 15
| align="right" | 100
| align="center" | [[Category 3 cable|Cat&nbsp;3]]
| align="right" | 16
| {{N/A|''Market failure''}}
|}

{| class="wikitable" style="float: right; margin: 0 1em 1em 0; text-align:center;"
|+ [[8P8C]] wiring ([[ANSI/TIA-568]] T568A)
! Pin !! Pair !! Wire !! Color
|- style="background:#6f6;"
| 1 || 3 || +/tip
|  style="background:white; text-align:left;"| [[File:Wire white green stripe.svg|60px|Pair 3 Wire 1]] white/green
|- style="background:#6f6;"
| 2 || 3 || −/ring
|  style="background:white; text-align:left;"| [[File:Wire green.svg|60px|Pair 3 Wire 2]] green
|- style="background:#fc3;"
| 3 || 2 || +/tip
|  style="background:white; text-align:left;"| [[File:Wire white orange stripe.svg|60px|Pair 2 Wire 1]] white/orange
|- style="background:#69f;"
| 4 || 1 || +/ring
|  style="background:white; text-align:left;"| [[File:Wire blue.svg|60px|Pair 1 Wire 2]] blue
|- style="background:#69f;"
| 5 || 1 || -/tip
|  style="background:white; text-align:left;"| [[File:Wire white blue stripe.svg|60px|Pair 1 Wire 1]] white/blue
|- style="background:#fc3;"
| 6 || 2 || −/ring
|  style="background:white; text-align:left;"| [[File:Wire orange.svg|60px|Pair 2 Wire 2]] orange
|- style="background:#963;"
| 7 || 4 || +/tip
|  style="background:white; text-align:left;"| [[File:Wire white brown stripe.svg|60px|Pair 4 Wire 1]] white/brown
|- style="background:#963;"
| 8 || 4 || −/ring
|  style="background:white; text-align:left;"| [[File:Wire brown.svg|60px|Pair 4 Wire 2]] brown
|}
<br />
{| class="wikitable" style="float: right; margin: 0 1em 1em 0; text-align:center;"
|+ [[8P8C]] wiring ([[ANSI/TIA-568]] T568B)
! Pin !! Pair !! Wire !! Color
|- style="background:#fc3;"
| 1 || 2 || +/tip
|  style="background:white; text-align:left;"| [[File:Wire white orange stripe.svg|60px|Pair 2 Wire 1]] white/orange
|- style="background:#fc3;"
| 2 || 2 || −/ring
|  style="background:white; text-align:left;"| [[File:Wire orange.svg|60px|Pair 2 Wire 2]] orange
|- style="background:#6f6;"
| 3 || 3 || +/tip
|  style="background:white; text-align:left;"| [[File:Wire white green stripe.svg|60px|Pair 3 Wire 1]] white/green
|- style="background:#69f;"
| 4 || 1 || +/ring
|  style="background:white; text-align:left;"| [[File:Wire blue.svg|60px|Pair 1 Wire 2]] blue
|- style="background:#69f;"
| 5 || 1 || -/tip
|  style="background:white; text-align:left;"| [[File:Wire white blue stripe.svg|60px|Pair 1 Wire 1]] white/blue
|- style="background:#6f6;"
| 6 || 3 || −/ring
|  style="background:white; text-align:left;"| [[File:Wire green.svg|60px|Pair 3 Wire 2]] green
|- style="background:#963;"
| 7 || 4 || +/tip
|  style="background:white; text-align:left;"| [[File:Wire white brown stripe.svg|60px|Pair 4 Wire 1]] white/brown
|- style="background:#963;"
| 8 || 4 || −/ring
|  style="background:white; text-align:left;"| [[File:Wire brown.svg|60px|Pair 4 Wire 2]] brown
|}

=== 100BASE-TX ===
[[File:3Com 3C905B.jpg|300px|thumb|right|3Com 3C905B-TX 100BASE-TX [[Peripheral Component Interconnect|PCI]] network interface card]]
'''100BASE-TX''' is the predominant form of Fast Ethernet, and runs over two pairs of wire inside a [[Category 5 cable|Category 5]] or above cable. Cable distance between nodes can be up to {{convert|100|m|ft|0}}. One pair is used for each direction, providing [[full-duplex]] operation at {{nowrap|100 Mbit/s}} in each direction.

Like [[10BASE-T]], the active pairs in a standard connection are terminated on pins 1, 2, 3 and 6. Since a typical Category 5 cable contains four pairs and the performance requirements of 100BASE-TX do not exceed the capabilities of even the worst-performing pair, one typical cable can carry two 100BASE-TX links with a simple wiring adaptor on each end.<ref>{{cite web|url=http://www.trinetusa.com/images/catalog/pages31-40.pdf |title=CAT5E Adapters |access-date=2012-12-17 |url-status=dead |archive-url=https://web.archive.org/web/20140707221928/http://www.trinetusa.com/images/catalog/pages31-40.pdf |archive-date=2014-07-07 }}</ref> Cabling is conventionally wired to one of [[ANSI/TIA-568]]'s termination standards, T568A or T568B. 100BASE-TX uses pairs 2 and 3 (orange and green).

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 [[Ethernet hub|hub]] or [[Network switch|switch]], creating a [[star network]]. Alternatively, it is possible to connect two devices directly using a [[Ethernet crossover cable|crossover cable]]. With today's equipment, crossover cables are generally not needed as most equipment supports auto-negotiation along with [[auto MDI-X]] to select and match speed, duplex and pairing.

With 100BASE-TX hardware, the raw bits, presented 4 bits wide clocked at 25&nbsp;MHz at the MII, go through [[4B5B]] binary encoding to generate a series of 0 and 1 symbols clocked at a 125&nbsp;MHz [[symbol rate]]. The 4B5B encoding provides DC equalization and spectrum shaping. 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, resulting in a maximum [[fundamental frequency]] of 31.25&nbsp;MHz. The procedure is borrowed from the ANSI X3.263 [[FDDI]] specifications, with minor changes.<ref name="mlt3">"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).</ref>

=== 100BASE-T1 ===
{{Broader|Ethernet over twisted pair#Single-pair}}

In '''100BASE-T1'''<ref>IEEE 802.3bw-2015 Clause 96</ref> the data is transmitted over a single copper pair, 3 bits per symbol, each transmitted as code pair using PAM3. It supports full-duplex transmission. The twisted-pair cable is required to support 66&nbsp;MHz, with a maximum length of 15&nbsp;m. No specific connector is defined. The standard is intended for automotive applications or when Fast Ethernet is to be integrated into another application. It was developed as [[Open Alliance BroadR-Reach]] (OABR) before IEEE standardization.<ref>{{Cite web|url=http://www.eetimes.com/document.asp?doc_id=1328371 |title=Driven by IEEE Standards, Ethernet Hits the Road in 2016 |publisher=EETimes |author=Junko Yoshida |date=2015-12-01 |access-date=2016-10-06}}</ref>

=== 100BASE-T2 === <!-- This section is linked from [[Ethernet over twisted pair]] -->
{| class="wikitable" style="float: right; margin: 0 0 1em 1em;"
|+ 100BASE-T2 symbols to [[PAM-5]] line modulation level mapping
|-
! Symbol !! Line signal level
|-
| 000 || 0
|-
| 001 || +1
|-
| 010 || −1
|-
| 011 || −2
|-
| 100 (ESC) || +2
|}

In '''100BASE-T2''', standardized in IEEE 802.3y, the data is transmitted over two copper pairs, but these pairs are only required to be Category 3 (voice grade) rather than the Category 5 required by 100BASE-TX. Data is transmitted and received on both pairs simultaneously<ref name="Breyer and Riley">{{cite book |title=Switched, Fast, and Gigabit Ethernet |author=Robert Breyer and Sean Riley |publisher=Macmillan Technical Publishing |year=1999 |page=107}}</ref> thus allowing full-duplex operation. Transmission uses 4 bits per symbol. The 4-bit symbol is expanded into two 3-bit symbols through a non-trivial scrambling procedure based on a [[linear-feedback shift register]].<ref>IEEE 802.3y</ref> 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. 100BASE-T2 was not widely adopted but the technology developed for it is used in 1000BASE-T.<ref name="TDG_ETH_2nd" />

=== 100BASE-T4 ===
<!-- This section is linked from [[Ethernet over twisted pair]] -->
'''100BASE-T4''' was an early implementation of Fast Ethernet. It required four twisted copper pairs of [[Category 3 cable|voice grade twisted pair]] (Category 3), a lower-performing cable compared to [[Category 5 cable]] used by 100BASE-TX. Maximum distance was limited to 100 meters. One pair was reserved for transmit and one for receive, and the remaining two switched direction. The fact that three pairs were used to transmit in each direction made 100BASE-T4 inherently half-duplex. Using three cable pairs allowed it to reach {{nowrap|100 Mbit/s}} while running at lower carrier frequencies, which allowed it to run on older cabling that many companies had recently installed for 10BASE-T networks.

A very unusual [[8B6T]] code was used to convert 8 data bits into 6 base-3 digits (the signal shaping is possible as there are nearly 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 were sent in parallel over three pairs using 3-level [[pulse-amplitude modulation]] (PAM-3).

100BASE-T4 was not widely adopted but some of the technology developed for it is used in [[1000BASE-T]].<ref name="TDG_ETH_2nd" /> Very few hubs were released with 100BASE-T4 support. Some examples include the [[3com]] 3C250-T4 Superstack II HUB 100, [[IBM]] 8225 Fast Ethernet Stackable Hub<ref>{{cite web |url=https://www.ibm.com/common/ssi/cgi-bin/ssialias?appname=skmwww&htmlfid=897%2FENUS196-117&infotype=AN&mhq=IBM%20Network%20Station%208361%20Series%20100&mhsrc=ibmsearch_a&subtype=CA |title=IBM 8225 Fast Ethernet Stackable Hub Hardware Announcement |website=[[IBM]] |date=May 28, 1996}}</ref> and [[Intel]] LinkBuilder FMS 100 T4.<ref>{{cite web|url=https://techlibrary.hpe.com/docs/products/eos/3Com-End-of-Sale%20dates.pdf|title=3Com Product End of Sale dates|website=[[Hewlett Packard Enterprise]]}}</ref><ref>{{cite web | url=https://manualzz.com/doc/3244934/intel-express-100base-t4-user-s-manual | title=Intel Express 100BASE-T4 User's Manual | website=Manualzz}}</ref> The same applies to [[network interface controller]]s. Bridging 100BASE-T4 with 100BASE-TX required additional network equipment.

=== 100BaseVG ===
{{Main|100BaseVG}}
Proposed and marketed by [[Hewlett-Packard]], 100BaseVG was an alternative design using category 3 cabling and a token concept instead of CSMA/CD. It was slated for standardization as IEEE 802.12 but it quickly vanished when switched 100BASE-TX became popular. The IEEE standard was later withdrawn.<ref name=vg/>

VG was similar to T4 in that it used more cable pairs combined with a lower carrier frequency to allow it to reach {{nowrap|100 Mbit/s}} on voice-grade cables. It differed in the way those cables were assigned. Whereas T4 would use the two extra pairs in different directions depending on the direction of data exchange, VG instead used two transmission modes. In one,  control, two pairs are used for transmission and reception as in classic Ethernet, while the other two pairs are used for [[Ethernet flow control|flow control]]. In the second mode, transmission, all four are used to transfer data in a single direction. The hubs implemented a [[token passing]] scheme to choose which of the attached nodes were allowed to communicate at any given time, based on signals sent to it from the nodes using control mode. When one node was selected to become active, it would switch to transfer mode, send or receive a packet, and return to control mode.<ref name=vg>{{cite web
|url=https://standards.ieee.org/findstds/standard/802.12-1995.html
|archive-url=https://web.archive.org/web/20140419124102/http://standards.ieee.org/findstds/standard/802.12-1995.html
|url-status=dead
|archive-date=April 19, 2014
|title=ANSI/IEEE 802.12-1995
|publisher=IEEE Standards Association
|access-date=2018-07-31}}</ref>

This concept was intended to solve two problems. The first was that it eliminated the need for collision detection and thereby reduced contention on busy networks. While any particular node may find itself throttled due to heavy traffic, the network as a whole would not end up losing efficiency due to collisions and the resulting rebroadcasts. Under heavy use, the total throughput was increased compared to the other standards. The other was that the hubs could examine the payload types and schedule the nodes based on their bandwidth requirements. For instance, a node sending a video signal may not require much bandwidth but will require it to be predictable in terms of when it is delivered. A VG hub could schedule access on that node to ensure it received the transmission timeslots it needed while opening up the network at all other times to the other nodes. This style of access was known as [[demand priority]].<ref name=vg/>

== Fiber optics ==
Fiber variants use [[fiber-optic cable]] with the listed interface types. Interfaces may be fixed or modular, often as [[Small Form-factor Pluggable]] (SFP).

{{Fibre legend}}

{| class="wikitable" style="line-height:110%;"
|-
! Name
! Standard
! Status
! style="width: 170px;" | Media
! Connector
! <small>Transceiver<br />Module</small>
! Reach<br />in m
! <small>#<br/>{{tooltip|Media|Number of physical media (wires/fibers) needed for bidirectional traffic}}<br/>(⇆)</small>
! <small>#<br/>{{tooltip|Lambdas|Number of wavelengths used in each direction}}<br/>(→)</small>
! <small>#<br/>{{tooltip|Lanes|Number of lanes (on the wire/fiber) in each direction}}<br/>(→)</small>
! Notes
|-
| colspan="11" {{partial|'''Fast Ethernet''' – <small>([[Data signaling rate|Data rate]]: {{nowrap|100 Mbit/s}} – [[Line code]]: [[4B5B]] × [[NRZI]] – Line rate: 125&nbsp;[[MBd]] – Full-Duplex / Half-Duplex)</small>}}
|-
| rowspan="3" | {{nowrap|[[Fast Ethernet#100BASE-FX|100BASE-FX]]}}
| rowspan="3" | {{nowrap|802.3u-1995}}<br /><small>(CL24/26)</small>
| rowspan="3" {{active|current}}
| rowspan="3" {{CGuest|fiber<br /><small>'''{{fontcolour|#F88379|1300&nbsp;nm}}'''</small>}}
| rowspan="3" {{CGuest|ST<br /> SC<br /> {{no wrap|MT-RJ}}<br /> MIC (FDDI)}}
| rowspan="3" {{N/A}}
| style="background-color:orange" | {{nowrap|FDDI: 2k (FDX)}}
| rowspan="3" align="right" | 2
| rowspan="3" align="right" | 1
| rowspan="3" align="right" | 1
| rowspan="3" | <small>max. 412&nbsp;m for half-duplex connections to ensure collision detection;<br />specification largely derived from FDDI.<br />[[Modal bandwidth]]: 800&nbsp;MHz·km</small> <ref>{{cite web |url=https://www.ccontrols.com/pdf/ExtV2N6.pdf |title=Introduction To Fast Ethernet |publisher=Contemporary Control Systems, Inc. |date=2001-11-01 |access-date=2018-08-25}}</ref><ref name="MOXA-EDS408A-datasheet">{{cite web |url=https://www.moxa.com/en/products/industrial-network-infrastructure/ethernet-switches/layer-2-managed-switches/eds-408a-series/eds-408a-mm-st |title=Datasheet for EDS-408A-MM-ST |publisher=MOXA  |date=2019-08-06}}</ref>
|-
| style="background-color:orange" | {{nowrap|OM1: 4k}}
|-
| style="background-color:orange" | {{nowrap|50/125: 5k}}
|-
| rowspan="5" | {{nowrap|[[Fast Ethernet#100BASE-LFX|100BASE-LFX]]}}
| rowspan="5" {{partial|''proprietary<br /><small>(non IEEE)</small>''}}
| rowspan="5" {{active|current}}
| rowspan="5" {{CGuest|fiber<br /><small>'''{{fontcolour|#F88379|1310&nbsp;nm}}'''</small>}}
| rowspan="5" {{CGuest|LC (SFP)<br />ST<br />SC}}
| rowspan="5" align="center" | SFP
| style="background-color:orange" | {{nowrap|OM1: 2k}} 
| rowspan="5" align="right" | 2
| rowspan="5" align="right" | 1
| rowspan="5" align="right" | 1
| rowspan="5" | <small>vendor-specific<br /> FP laser transmitter<br />Full-duplex<br />[[Modal bandwidth]]: 800&nbsp;MHz·km</small> <ref name="MOXA-1fe-datasheet">{{cite web |url=https://www.moxa.com/getmedia/97d0d84d-3574-4456-a8b1-ee24aeaf04fc/moxa-sfp-1fe-series-datasheet-v1.0.pdf |title=Datasheet for SFP-1FE Series |publisher=MOXA  |date=2018-10-12 |access-date=2020-03-21}}</ref>
|-
| style="background-color:orange" | {{nowrap|OM2: 2k}}
|-
| style="background-color:orange" | {{nowrap|62.5/125: 4k}}
|-
| style="background-color:orange" | {{nowrap|50/125: 4k}}
|-
| style="background-color:yellow" | {{nowrap|OSx: 40k<ref name="MOXA-EDS408A-datasheet" />}}
|-
| rowspan="2" | {{nowrap|[[100BASE-SX]]}}
| rowspan="2" {{partial|{{nowrap|TIA-785<br />(2000)}}}}
| rowspan="2" {{partial|legacy}}
| rowspan="2" {{CGuest|fiber<br /><small>'''{{fontcolour|red|850&nbsp;nm}}'''</small>}}
| rowspan="2" {{CGuest|ST<br />SC<br />LC}}
| rowspan="2" {{N/A}}
| style="background-color:orange" | {{nowrap|OM1: 300}}
| rowspan="2" align="right" | 2
| rowspan="2" align="right" | 1
| rowspan="2" align="right" | 1
| rowspan="2" | <small>optics sharable with 10BASE-FL, thus making it possible to have an auto-negotiation scheme and use 10/100 fiber adapters.</small>
|-
| style="background-color:orange" | {{nowrap|OM2: 300}}
|-
| {{nowrap|[[100BASE-LX10]]}}
| rowspan="2" | {{nowrap|802.3ah-2004}}<br /><small>(CL58)</small>
| {{partial|phase-out}}
| {{CGuest|fiber<br /><small>'''{{fontcolour|#F88379|1310&nbsp;nm}}'''</small>}}
| rowspan="2" {{CGuest|LC}}
| rowspan="2" align="center" | <small>'''SFP'''</small>
| style="background-color:yellow" | {{nowrap|OSx: 10k}}
| style="text-align:right;" | 2
| rowspan="2" align="right" | 1
| rowspan="2" align="right" | 1
| <small>'''full-duplex only'''</small>
|-
| {{nowrap|[[Fast Ethernet#100BASE-BX10|100BASE-BX10]]}}
| {{partial|phase-out}}
| {{CGuest|fiber<br /><small>'''{{nowrap|TX: {{fontcolour|#F88379|1310&nbsp;nm}}<br />RX: {{fontcolour|#F49AC2|1550&nbsp;nm}}}}'''</small>}}
| style="background-color:yellow" | {{nowrap|OSx: 40k}}
| style="text-align:right;" | 1
| <small>'''full-duplex only''';<br />optical multiplexer used to split TX and RX signals into different wavelengths.</small>
|-
|}

===Fast Ethernet SFP ports===
Fast Ethernet speed is not available on all SFP ports,<ref>{{cite web |title=Cisco 350 Series Data Sheet |url=https://www.cisco.com/c/en_in/products/collateral/switches/small-business-smart-switches/data-sheet-c78-737359.html |website=Cisco |access-date=22 March 2020 |language=en}}</ref> but supported by some devices.<ref>{{cite web |title=Cisco 100BASE-X SFP Data Sheet |url=https://www.cisco.com/c/en/us/products/collateral/interfaces-modules/fast-ethernet-sfp-modules/product_data_sheet0900aecd801f931c.html |website=Cisco |access-date=26 March 2020 |language=en}}</ref><ref>{{cite web |title=FS GLC-GE-100FX Transceiver |url=https://www.fs.com/products/12672.html |website=FS |access-date=26 March 2020 |language=en}}</ref> An SFP port for [[Gigabit Ethernet]] should not be assumed to be backwards compatible with Fast Ethernet.

=== Optical interoperability ===
To have interoperability there are some criteria that have to be met:<ref>{{cite web |title=Fiber incompatabilities? – Ars Technica OpenForum |url=https://arstechnica.com/civis/viewtopic.php?p=6647265&sid=1207bc662946d0bf8ff15eac6753a819#p6647265 |website=arstechnica.com |access-date=29 March 2020 | date=2006-06-06}}{{self-published inline|date=May 2020}}</ref>
* [[Line encoding]]
* [[Wavelength]]{{efn|It may possible for certain types of optics to work with a mismatch in wavelength.<ref>{{cite web |title=Everything You Always Wanted to Know About Optical Networking – But Were Afraid to Ask |url=https://archive.nanog.org/sites/default/files/Steenbergen.Everything_You_Need.pdf |website=archive.nanog.org |publisher=Richard A Steenbergen |access-date=30 March 2020}}</ref>}}
* [[Duplex (telecommunications)|Duplex mode]]
* Media count
* Media type and dimension

100BASE-X Ethernet is not backward compatible with [[10BASE-F]] and is not forward compatible with [[1000BASE-X]].

===100BASE-FX=== 
100BASE-FX is a version of Fast Ethernet over [[optical fiber]]. The 100BASE-FX [[physical medium dependent]] (PMD) sublayer is defined by [[FDDI]]'s PMD,<ref>IEEE 802.3 clause 26.2 ''Functional specifications''</ref> so 100BASE-FX is not compatible with [[10BASE-FL]], the {{nowrap|10 Mbit/s}} version over optical fiber.

100BASE-FX is still used for existing installation of [[multimode fiber]] where more speed is not required, like industrial automation plants.<ref name="MOXA-EDS408A-datasheet" />

===100BASE-LFX=== 
100BASE-LFX is a non-standard term to refer to Fast Ethernet transmission. It is very similar to 100BASE-FX but achieves longer distances up to 4–5&nbsp;km over a pair of multi-mode fibers through the use of [[Fabry–Pérot]] laser transmitter<ref>{{cite web |url=https://www.fs.com/products/37324.html |title=Datasheet for SFP-100FX-31|publisher=FS.com |access-date=2020-03-21}}</ref> running on 1310&nbsp;nm wavelength. The signal attenuation per km at 1300&nbsp;nm is about half the loss of 850&nbsp;nm.<ref name="Fluke-Fiber">{{cite web |title= Knowledge Base Fiber |url=https://www.flukenetworks.com/knowledge-base/copper-testing/om1-om2-om3-om4-om5-and-os1-os2-fiber |website=Fluke Networks |access-date=8 April 2020 |language=en-us |date=28 February 2014}}</ref><ref>{{cite web |title=Differences between OM1, OM2, OM3, OM4, OS1, OS2 fiber optic cable nomenclatures |url=https://www.stl.tech/connectivity-solution/optical-fibre/pdf/Differences_between_OM1__OM2__OM3__OM4_.pdf |website=stl.tech |access-date=8 April 2020 |archive-date=18 May 2020 |archive-url=https://web.archive.org/web/20200518045943/https://www.stl.tech/connectivity-solution/optical-fibre/pdf/Differences_between_OM1__OM2__OM3__OM4_.pdf |url-status=dead }}</ref>

===100BASE-SX===
100BASE-SX is a version of Fast Ethernet over optical fiber standardized in TIA/EIA-785-1-2002. It is a lower-cost, shorter-distance alternative to 100BASE-FX. Because of the shorter wavelength used (850&nbsp;nm) and the shorter distance supported (up to 300&nbsp;m), 100BASE-SX may use less expensive optical components.

Because it uses the same wavelength as [[10BASE-FL]], the {{nowrap|10 Mbit/s}} version of Ethernet over optical fiber, 100BASE-SX can be backward-compatible with 10BASE-FL. Cost and compatibility makes 100BASE-SX an option for those upgrading from 10BASE-FL and who do not require longer distances.

===100BASE-LX10===
100BASE-LX10 is a version of Fast Ethernet over optical fiber standardized in 802.3ah-2004 clause 58. It has a 10&nbsp;km reach over a pair of single-mode fibers.

===100BASE-BX10===
100BASE-BX10 is a version of Fast Ethernet over optical fiber standardized in 802.3ah-2004 clause 58. It uses an optical multiplexer to split TX and RX signals into different wavelengths on the same fiber. It has a 10&nbsp;km reach over a single strand of single-mode fiber.

===100BASE-EX===
100BASE-EX is very similar to 100BASE-LX10 but achieves longer distances up to 40&nbsp;km over a pair of single-mode fibers due to higher quality optics than a LX10, running on 1310&nbsp;nm wavelength lasers. 100BASE-EX is not a formal standard but industry-accepted term.<ref name="FS-GLC-FE-100EX">{{cite web |title=GLC-FE-100EX 100BASE-EX SFP (mini-GBIC) Transceiver |url=https://www.fs.com/de-en/products/12678.html |website=FS.com |access-date=21 March 2020 |language=en}}</ref> It is sometimes referred to as 100BASE-LH (long haul), and is easily confused with 100BASE-LX10 or 100BASE-ZX because the use of -LX(10), -LH, -EX, and -ZX is ambiguous between vendors.

===100BASE-ZX===
100BASE-ZX is a non-standard but multi-vendor<ref name="FS-SFP-100ZX-55">{{cite web |title=FS-GLC-FE-100ZX 100BASE-ZX |url=https://www.fs.com/products/12679.html |website=FS.com |access-date=21 March 2020 |language=en}}</ref>{{Better source needed|date=February 2021}} term to refer to Fast Ethernet transmission using 1,550&nbsp;nm wavelength to achieve distances of at least 70&nbsp;km over single-mode fiber. Some vendors specify distances up to 160&nbsp;km over single-mode fiber, sometimes called 100BASE-EZX. Ranges beyond 80&nbsp;km are highly dependent upon the path loss of the fiber in use, specifically the attenuation figure in dB per km, the number and quality of connectors/patch panels and splices located between transceivers.<ref>{{cite web |title=SFP15160FE0B / SFP / 100BASE-eZX |url=https://www.skylaneoptics.com/en/product/sfp15160fe0b-sfp-100base-ezx/ |website=Skylane Optics |access-date=21 March 2020|archive-url=https://web.archive.org/web/20200819045024/https://www.skylaneoptics.com/en/product/sfp15160fe0b-sfp-100base-ezx/|archive-date=August 19, 2020|url-status=dead}}</ref>

== See also ==
* [[List of interface bit rates]]

==Notes==
{{Notelist}}

==References==
{{Reflist}}

==External links==
* [https://web.archive.org/web/20080916221133/http://www.cs.bsu.edu/homepages/peb/cs637/ethernet/100mbps.htm Common {{nowrap|100 Mbit/s}} Hardware Variations]
* [http://www.inetdaemon.com/tutorials/networking/lan/ethernet/origins.shtml Origins and History of Ethernet]
* [https://ieeexplore.ieee.org/browse/standards/get-program/page/series?id=68 IEEE802.3 standards free download]
* [https://web.archive.org/web/20121009212203/http://www.hp.com/rnd/pdfs/100FXtechbrief.pdf ProCurve Networking 100BASE-FX Technical Brief]

{{Ethernet}}

[[Category:Ethernet standards]]
[[Category:Computer networking]]