Two new variants of 10megabit per second Ethernet over a single twisted pair, known as 10BASE-T1S and 10BASE-T1L, were standardized in IEEE Std 802.3cg-2019.[2] 10BASE-T1S has its origins in the automotive industry and may be useful in other short-distance applications where substantial electrical noise is present.[3] 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 XL in the automotive space and includes a PHY-Level Collision Avoidance scheme (PLCA).[4]
The earlier standards use 8P8C modular connectors,[lower-alpha 2] and supported cable standards range from 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[5] and IEC 63171-6.[6]
History
The first two early designs of twisted-pair networking were StarLAN, standardized by the IEEE Standards Association as IEEE 802.3e in 1986, at one megabit per second,[7] and LattisNet, developed in January 1987, at 10 megabit per second.[8][9] Both were developed before the 10BASE-T standard (published in 1990 as IEEE 802.3i) and used different signaling, so they were not directly compatible with it.[10]
In 1988, AT&T released StarLAN10, named for working at 10Mbit/s.[11] The StarLAN10 signaling was used as the basis of 10BASE-T, with the addition of link beat to quickly indicate connection status.[lower-alpha 3]
Using twisted-pair cabling in a star topology addressed several weaknesses of the previous Ethernet standards:
Twisted-pair cables were already in use for telephone service and were already present in many office buildings, lowering the overall cost of deployment
The centralized star topology was also already often in use for telephone service cabling, as opposed to the bus topology required by earlier Ethernet standards
Using point-to-point links was less prone to failure and greatly simplified troubleshooting compared to a shared bus
Mixing different speeds in a single network became possible with the arrival of Fast Ethernet
Depending on cable grades, subsequent upgrading to Gigabit Ethernet or faster could be accomplished by replacing the network switches
Although 10BASE-T is rarely used as a normal-operation signaling rate today, it is still in wide use with network interface controllers in wake-on-LAN power-down mode and for special, low-power, low-bandwidth applications. 10BASE-T is still supported on most twisted-pair Ethernet ports with up to Gigabit Ethernet speed.
The common names for the standards derive from aspects of the physical media. The leading number (10 in 10BASE-T) refers to the transmission speed in Mbit/s. BASE denotes that baseband transmission is used. The T designates twisted-pair cable. Where there are several standards for the same transmission speed, they are distinguished by a letter or digit following the T, such as TX or T4, referring to the encoding method and number of lanes.[13]
Most Ethernet cables are wired straight-through (pin 1 to pin 1, pin 2 to pin 2, and so on). In some instances, the crossover form (receive to transmit and transmit to receive) may still be required.
Cables for Ethernet may be wired to either the T568A or T568B termination standards at both ends of the cable. Since these standards differ only in that they swap the positions of the two pairs used for transmitting and receiving, a cable with T568A wiring at one end and T568B wiring at the other results in a crossover cable.
A 10BASE-T or 100BASE-TX host uses a connector wiring called medium dependent interfaces (MDI), transmitting on pins 1 and 2 and receiving on pins 3 and 6 to a network device. An infrastructure node (a hub or a switch) accordingly uses a connector wiring called MDI-X, transmitting on pins 3 and 6 and receiving on pins 1 and 2. These ports are connected using a straight-through cable so each transmitter talks to the receiver on the other end of the cable.
Nodes can have two types of ports: MDI (uplink port) or MDI-X (regular port, 'X' for internal crossover). Hubs and switches have regular ports. Routers, servers and end hosts (e.g. personal computers) have uplink ports. When two nodes having the same type of ports need to be connected, a crossover cable may be required, especially for older equipment. Connecting nodes having different types of ports (i.e., MDI to MDI-X and vice versa) requires a straight-through cable. Thus connecting an end host to a hub or switch requires a straight-through cable. Some older switches and hubs provided a button to allow a port to act as either a normal (regular) or an uplink port, i.e. using MDI-X or MDI pinout, respectively.
Many modern Ethernet host adapters can automatically detect another computer connected with a straight-through cable and then automatically introduce the required crossover if needed; if neither of the adapters has this capability, then a crossover cable is required. Most newer switches have auto MDI-X on all ports allowing all connections to be made with straight-through cables. If both devices being connected support 1000BASE-T according to the standards, they will connect regardless of whether a straight-through or crossover cable is used.[14]
A 10BASE-T transmitter sends two differential voltages, +2.5V or −2.5V. A 100BASE-TX transmitter sends three differential voltages, +1V, 0V, or −1V.[15] Unlike earlier Ethernet standards using broadband and coaxial cable, such as 10BASE5 (thicknet) and 10BASE2 (thinnet), 10BASE-T does not specify the exact type of wiring to be used but instead specifies certain characteristics that a cable must meet. This was done in anticipation of using 10BASE-T in existing twisted-pair wiring systems that did not conform to any specified wiring standard. Some of the specified characteristics are attenuation, characteristic impedance, propagation delay, and several types of crosstalk. Cable testers are widely available to check these parameters to determine if a cable can be used with 10BASE-T. These characteristics are expected to be met by 100 meters of 24-gauge unshielded twisted-pair cable. However, with high-quality cabling, reliable cable runs of 150 meters or longer are often achievable and are considered viable by technicians familiar with the 10BASE-T specification.[citation needed]
100BASE-TX follows the same wiring patterns as 10BASE-T, but is more sensitive to wire quality and length, due to the higher bit rates.
1000BASE-T uses all four pairs bi-directionally using hybrid circuits and cancellers.[16] Data is encoded using 4D-PAM5; four dimensions using pulse-amplitude modulation (PAM) with five voltages, −2V, −1V, 0V, +1V, and +2V.[17] While +2V to −2V may appear at the pins of the line driver, the voltage on the cable is nominally +1V, +0.5V, 0V, −0.5V and −1V.[18]
100BASE-TX and 1000BASE-T were both designed to require a minimum of category 5 cable and also specify a maximum cable length of 100 metres (330ft). Category 5 cable has since been deprecated and new installations use Category 5e.
10BASE-T and 100BASE-TX require only two pairs (pins 1–2, 3–6) to operate. Since common Category 5 cable has four pairs, it is possible to use the spare pairs (pins 4–5, 7–8) in 10- and 100-Mbit/s configurations for other purposes. The spare pairs may be used for power over Ethernet (PoE), for two plain old telephone service (POTS) lines, or for a second 10BASE-T or 100BASE-TX connection. In practice, great care must be taken to separate these pairs as 10/100-Mbit/s Ethernet equipment electrically terminates the unused pins ("Bob Smith Termination").[19] Shared cable is not an option for Gigabit Ethernet as 1000BASE-T requires all four pairs to operate.
Single-pair
In addition to the more computer-oriented two and four-pair variants, the 10BASE-T1,[20]100BASE-T1[21] and 1000BASE-T1[22] single-pair Ethernet (SPE) physical layers are intended for industrial and automotive applications[23] or as optional data channels in other interconnect applications.[24] The distances that single pair operates at full duplex depends on the speed: 1000m (1km) with 802.3cg-2019 10BASE-T1L; 15m or 49ft with 100BASE-T1 (link segment type A); up to 40m or 130ft using 1000BASE-T1 link segment type B with up to four in-line connectors. Both physical layers require a balanced twisted pair with an impedance of 100Ω. The cable must be capable of transmitting 600MHz for 1000BASE-T1 and 66MHz for 100BASE-T1. 2.5Gb/s, 5Gb/s, and 10Gb/s over a 15m single pair is standardized in 802.3ch-2020.[25] In June 2023, 802.3cy added 25Gb/s speeds at lengths up to 11m.[26]
Cat 6A cable with an M12X connector in one end and a modular connector in the other
8P8C modular connector: For stationary uses in controlled environments, from homes to datacenters, this is the dominant connector. Its fragile locking tab otherwise limits its suitability and durability. Bandwidths supporting up to Cat 8 cabling are defined for this connector format.
M12X: This is the M12 connector designated for Ethernet, standardized as IEC 61076-2-109. It is a 12mm metal screw that houses 4 shielded pairs of pins. Nominal bandwidth is 500MHz (Cat 6A). The connector family is used in chemically and mechanically harsh environments such as factory automation and transportation. Its size is similar to the modular connector.
ix Industrial:[28] This connector is designed to be small yet strong. It has 10 pins and a different locking mechanism than the modular connector. Standardized as IEC 61076-3-124, its nominal bandwidth is 500MHz (Cat 6A).
IEC 63171-1 "LC":[5] This is a 2-pin connector with a similar locking tab to the modular connector, if thicker.
IEC 63171-6 "industrial":[6] This standard defines 5 2-pin connectors that differ in their locking mechanisms and one 4-pin connector with dedicated pins for power. The locking mechanisms range from a metal locking tab to M8 and M12 connectors with screw or push-pull locking. The 4-pin connector is only defined with M8 screw locking.
Autonegotiation and duplex
Ethernet over twisted-pair standards up through Gigabit Ethernet define both full-duplex and half-duplex communication. However, half-duplex operation for gigabit speed is not supported by any existing hardware.[29][30] Higher speed standards, 2.5GBASE-T up to 40GBASE-T[31] running at 2.5 to 40Gbit/s, consequently define only full-duplex point-to-point links which are generally connected by network switches, and do not support the traditional shared-medium CSMA/CD operation.[32]
Many different modes of operations (10BASE-T half-duplex, 10BASE-T full-duplex, 100BASE-TX half-duplex, etc.) exist for Ethernet over twisted pair, and most network adapters are capable of different modes of operation. Autonegotiation is required in order to make a working 1000BASE-T connection.
When two linked interfaces are set to different duplex modes, the effect of this duplex mismatch is a network that functions much more slowly than its nominal speed. Duplex mismatch may be inadvertently caused when an administrator configures an interface to a fixed mode (e.g. 100Mbit/s full-duplex) and fails to configure the remote interface, leaving it set to autonegotiate. Then, when the auto-negotiation process fails, half-duplex is assumed by the autonegotiating side of the link.
Variants
Comparison of twisted-pair-based Ethernet physical transport layers (TP-PHYs)[33]
1 2 Transfer speed= lanes× bits per hertz× spectral bandwidth
1 2 Effective bit/s per hertz per lane after loss to encoding overhead
1 2 The spectral bandwidth is the maximum rate at which the signal will complete one cycle. It is typically half the symbol rate, because one can send a symbol both at the positive and negative peak of the cycle. Exceptions are 10BASE-T where it is equal because it uses Manchester code, and 100BASE-TX where it is one quarter because it uses MLT-3 encoding.
1 2 At shorter cable length, it is possible to use cables of a lower grade than required for 100m. For example, it is possible to use 10GBASE-T on a Cat 6 cable of 55m or less. Likewise 5GBASE-T is expected to work with Cat5e in most use cases.
↑ 15m for point-to-point links, 25m for mixing/multi-tap segments
↑ 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.[1]:123
Ethernet is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1983 as IEEE 802.3. Ethernet has since been refined to support higher bit rates, a greater number of nodes, and longer link distances, but retains much backward compatibility. Over time, Ethernet has largely replaced competing wired LAN technologies such as Token Ring, FDDI and ARCNET.
100BaseVG is a 100 Mbit/s Ethernet standard specified to run over four pairs of Category 3 cable. It is also called 100VG-AnyLAN because it was defined to carry both Ethernet and Token Ring frame types.
Category 5 cable (Cat 5) is a twisted pair cable for computer networks. Since 2001, the variant commonly in use is the Category 5e specification (Cat 5e). The cable standard provides performance of up to 100 MHz and is suitable for most varieties of Ethernet over twisted pair up to 2.5GBASE-T but more commonly runs at 1000BASE-T speeds. Cat 5 is also used to carry other signals such as telephone and video.
In computer networking, Fast Ethernet physical layers carry traffic at the nominal rate of 100 Mbit/s. The prior Ethernet speed was 10 Mbit/s. Of the Fast Ethernet physical layers, 100BASE-TX is by far the most common.
In computer networking, Gigabit Ethernet is the term applied to transmitting Ethernet frames at a rate of a gigabit per second. The most popular variant, 1000BASE-T, is defined by the IEEE 802.3ab standard. It came into use in 1999, and has replaced Fast Ethernet in wired local networks due to its considerable speed improvement over Fast Ethernet, as well as its use of cables and equipment that are widely available, economical, and similar to previous standards. The first standard for faster 10 Gigabit Ethernet was approved in 2002.
Category 3 cable, commonly known as Cat 3 or station wire, and less commonly known as VG or voice-grade, is an unshielded twisted pair (UTP) cable used in telephone wiring. It is part of a family of standards defined jointly by the Electronic Industries Alliance (EIA) and the Telecommunications Industry Association (TIA) and published in TIA/EIA-568-B.
StarLAN was the first IEEE 802.3 standard for Ethernet over twisted pair wiring. It was standardized by the IEEE Standards Association as 802.3e in 1986, as the 1BASE5 version of Ethernet. The StarLAN Task Force was chaired by Bob Galin.
A registered jack (RJ) is a standardized telecommunication network interface for connecting voice and data equipment to a computer service provided by a local exchange carrier or long distance carrier. Registered interfaces were first defined in the Universal Service Ordering Code (USOC) system of the Bell System in the United States for complying with the registration program for customer-supplied telephone equipment mandated by the Federal Communications Commission (FCC) in the 1970s. They were subsequently codified in title 47 of the Code of Federal Regulations Part 68. Registered jack connections began to see use after their invention in 1973 by Bell Labs. The specification includes physical construction, wiring, and signal semantics. Accordingly, registered jacks are primarily named by the letters RJ, followed by two digits that express the type. Additional letter suffixes indicate minor variations. For example, RJ11, RJ14, and RJ25 are the most commonly used interfaces for telephone connections for one-, two-, and three-line service, respectively. Although these standards are legal definitions in the United States, some interfaces are used worldwide.
Power over Ethernet (PoE) describes any of several standards or ad hoc systems that pass electric power along with data on twisted-pair Ethernet cabling. This allows a single cable to provide both a data connection and enough electricity to power networked devices such as wireless access points (WAPs), IP cameras and VoIP phones.
An Ethernet hub, active hub, network hub, repeater hub, multiport repeater, or simply hub is a network hardware device for connecting multiple Ethernet devices together and making them act as a single network segment. It has multiple input/output (I/O) ports, in which a signal introduced at the input of any port appears at the output of every port except the original incoming. A hub works at the physical layer. A repeater hub also participates in collision detection, forwarding a jam signal to all ports if it detects a collision. In addition to standard 8P8C ("RJ45") ports, some hubs may also come with a BNC or an Attachment Unit Interface (AUI) connector to allow connection to legacy 10BASE2 or 10BASE5 network segments.
Autonegotiation is a signaling mechanism and procedure used by Ethernet over twisted pair by which two connected devices choose common transmission parameters, such as speed, duplex mode, and flow control. In this process, the connected devices first share their capabilities regarding these parameters and then choose the highest performance transmission mode they both support.
A medium-dependent interface (MDI) describes the interface in a computer network from a physical-layer implementation to the physical medium used to carry the transmission. Ethernet over twisted pair also defines a medium-dependent interface – crossover (MDI-X) interface. Auto–MDI-X ports on newer network interfaces detect if the connection would require a crossover and automatically choose the MDI or MDI-X configuration to complement the other end of the link.
An Ethernet crossover cable is a crossover cable for Ethernet used to connect computing devices together directly. It is most often used to connect two devices of the same type, e.g. two computers or two switches to each other. By contrast, straight through patch cables are used to connect devices of different types, such as a computer to a network switch.
The physical-layer specifications of the Ethernet family of computer network standards are published by the Institute of Electrical and Electronics Engineers (IEEE), which defines the electrical or optical properties and the transfer speed of the physical connection between a device and the network or between network devices. It is complemented by the MAC layer and the logical link layer. An implementation of a specific physical layer is commonly referred to as PHY.
Ethernet in the first mile (EFM) refers to using one of the Ethernet family of computer network technologies between a telecommunications company and a customer's premises. From the customer's point of view, it is their first mile, although from the access network's point of view it is known as the last mile.
A fiber media converter is a simple networking device that makes it possible to connect two dissimilar media types such as twisted pair with fiber optic cabling. They were introduced to the industry in the 1990s, and are important in interconnecting fiber optic cabling-based systems with existing copper-based structured cabling systems. They are also used in metropolitan area network (MAN) access and data transport services to enterprise customers.
10 Gigabit Ethernet is a group of computer networking technologies for transmitting Ethernet frames at a rate of 10 gigabits per second. It was first defined by the IEEE 802.3ae-2002 standard. Unlike previous Ethernet standards, 10GbE defines only full-duplex point-to-point links which are generally connected by network switches; shared-medium CSMA/CD operation has not been carried over from the previous generations of Ethernet standards so half-duplex operation and repeater hubs do not exist in 10GbE. The first standard for faster 100 Gigabit Ethernet links was approved in 2010.
ANSI/TIA-568 is a technical standard for commercial building cabling for telecommunications products and services. The title of the standard is Commercial Building Telecommunications Cabling Standard and is published by the Telecommunications Industry Association (TIA), a body accredited by the American National Standards Institute (ANSI).
The OPEN Alliance is a non-profit, special interest group (SIG) of mainly automotive industry and technology providers collaborating to encourage wide scale adoption of Ethernet-based communication as the standard in automotive networking applications.
IEEE 802.3bz, NBASE-T and MGBASE-T are standards released in 2016 for Ethernet over twisted pair at speeds of 2.5 and 5 Gbit/s. These use the same cabling as the ubiquitous Gigabit Ethernet, yet offer higher speeds. The resulting standards are named 2.5GBASE-T and 5GBASE-T.
1 2 IEC 63171-1 (draft 48B/2783/FDIS, 17 Jan. 2020), Connectors for electrical and electronic equipment—Part 1: Detail specification for 2-way, shielded or unshielded, free and fixed connectors: mechanical mating information, pin assignment and additional requirements for TYPE 1 / Copper LC style. International Electrotechnical Commission. 2020.
1 2 IEC 63171-6:2020, Connectors for electrical and electronic equipment—Part 6: Detail specification for 2-way and 4-way (data/power), shielded, free and fixed connectors for power and data transmission with frequencies up to 600MHz. International Electrotechnical Commission. 2020.
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