Editing Ethernet over twisted pair (section)

{{Short description|Ethernet physical layers using twisted-pair cables}}
{{Use American English|date = March 2019}}

{{multiple image|direction=vertical
| image1 = 10baseT cable.jpeg
| caption1 = Standard twisted-pair cable usable for most common types of Ethernet
| image2 = 10baseT jack.png
| caption2 = [[8P8C]] plug
}}

'''Ethernet over twisted-pair''' technologies use [[twisted-pair cable]]s for the [[physical layer]] of an [[Ethernet]] computer network. They are a subset of all [[Ethernet physical layer]]s.

Early Ethernet used various grades of [[coaxial cable]], but in 1984, [[StarLAN]] showed the potential of simple [[unshielded twisted pair]]. This led to the development of '''10BASE-T''' and its successors [[100BASE-TX]], [[1000BASE-T]], [[10GBASE-T]] and [[40GBASE-T]], supporting speeds of 10 and 100&nbsp;[[megabit per second]], then 1, 10 and 40 gigabit per second respectively.{{efn|Generally, the higher-speed implementations support the lower-speed standards making it possible to mix different generations of equipment; with the inclusive capability designated 10/100 or 10/100/1000 for connections that support such combinations.<ref>{{cite book |title= Ethernet: the definitive guide |author= Charles E. Spurgeon |year= 2000 |publisher= OReilly Media |isbn= 978-1-56592-660-8 |url= https://books.google.com/books?id=MRChaUQr0Q0C&pg=PA123 }}</ref>{{rp|123}}}} 

Two new variants of 10&nbsp;megabit per second Ethernet over a ''single'' twisted pair, known as '''10BASE-T1S''' and '''10BASE-T1L''', were standardized in IEEE Std 802.3cg-2019.<ref name=ieee802.3CG>{{cite web|title=PhysicalLayers Specifications and Management Parameters for 10 Mb/s Operation and Associated Power Delivery over a Single Balanced Pair of Conductors|url=https://standards.ieee.org/standard/802_3cg-2019.html|archive-url=https://web.archive.org/web/20200318015954/https://standards.ieee.org/standard/802_3cg-2019.html|url-status=dead|archive-date=March 18, 2020|publisher=IEEE 802.3}}</ref> 10BASE-T1S has its origins in the [[automotive industry]] and may be useful in other short-distance applications where substantial electrical noise is present.<ref>{{citation |url=https://www.analog.com/en/thought-leadership/why-10base-t1s-is-the-missing-ethernet-link.html |title=Why 10BASE-T1S Is the Missing Ethernet Link for Automotive Communications |author=Fionn Hurley |publisher=[[Analog Devices]]}}</ref> 10BASE-T1L is a long-distance Ethernet, supporting connections up to 1 km in length. Both of these standards are finding applications implementing the [[Internet of things]]. 10BASE-T1S is a direct competitor of [[CAN bus|CAN XL]] in the automotive space and includes a [[PHY-Level Collision Avoidance]] scheme (PLCA).<ref>{{cite conference | last1=Cena | first1=Gianluca | last2=Scanzio | first2=Stefano | last3=Valenzano | first3=Adriano | title=Composite CAN XL-Ethernet Networks for Next-Gen Automotive and Automation Systems | conference=2023 IEEE 19th International Conference on Factory Communication Systems (WFCS) | publisher=IEEE | date=2023-04-26 | doi=10.1109/wfcs57264.2023.10144116 | arxiv=2306.09498 }}</ref>

The earlier standards use [[8P8C modular connector]]s,{{efn|The [[8P8C modular connector]] is often called ''RJ45'' after a [[Registered jack|telephone industry standard]].}} and supported cable standards range from [[Category 3 cable|Category 3]] to [[Category 8]]. These cables typically have four pairs of wires for each connection, although early Ethernet used only two of the pairs. Unlike the earlier -T standards, the -T1 interfaces were designed to operate over a single pair of conductors and introduce the use of two new connectors referred to as IEC 63171-1<ref name="IEC 63171-1" /> and IEC 63171-6.<ref name="IEC 63171-6" />