This article includes a list of references, related reading, or external links, but its sources remain unclear because it lacks inline citations .(April 2023) |
A Medium Attachment Unit (MAU) is a transceiver which converts signals on an Ethernet cable to and from Attachment Unit Interface (AUI) signals.
On original 10BASE5 (thicknet) Ethernet equipment, the MAU was typically clamped to the Ethernet wire via a vampire tap and connected by a multi-wire cable to the computer via a DA-15 port, which was also present on the network interface controller (NIC). This AUI cable could be up to 50 metres (160 ft) long, but was typically much shorter. With later standards, thicknet vampire taps and N connectors gave way to BNC connectors (for thinnet coax cables) and 8P8C connectors (for twisted-pair cables). MAUs for these were still connected to NICs via AUI cables, but soon the MAU ceased to be a separate adapter and was generally integrated into the NIC. Eventually, the entire Ethernet controller was often integrated into a single integrated circuit (chip) to reduce cost.
In most modern switched or hubbed Ethernet over twisted pair systems, neither the MAU nor the AUI interfaces exist (apart, perhaps as notional entities for the purposes of thinking about layering the interface), and the category 5 (CAT5) (or better) cable connects directly into an Ethernet socket on the host or router. For backward compatibility with equipment that still had external AUI interfaces only, adapter-type MAUs with 10BASE2 or 10BASE-T connectors long remained available after the obsolescence of original vampire tap MAUs, but even adapter-type MAUs have become very rare as of the 2020s.
The original Ethernet's successor standard, Fast Ethernet, introduced division into medium access control (MAC) and physical (PHY) layers connected with media-independent interface (MII). Some early Fast Ethernet hardware had physical external MII connectors, functionally similar to the AUI connector, but generally separate adaptors became obsolete. However, the tradition of using a separate low-level I/O device in networking has continued in fast optical fiber network interfaces, where the GBIC, XENPAK, XFP, and enhanced small form-factor pluggable (SFP+) pluggable transceiver modules using the XAUI interface play a similar role.
The main difference between AUI and MII is that the AUI deals with line-coded signals, which is specific to the physical medium (10BASE5, 10BASE2 and 10BASE-T all use the same line code), while MII is genuinely media-independent. So while MII and AUI as external connections were similar from a user's point of view, in terms of signalling the equivalent of MII for classic Ethernet were the non-standardized interfaces between MAC and Serial Interface as found in e.g. the Am7990 family.
The purpose of a MAU is to provide the physical means for communication between local network data link entities. As a physical interface, an MAU can be implemented independently among different hardware manufacturers and achieve the intended level of compatibility when interconnected in a common local network. It also allows for ease of installation and service.
MAUs provide an easily accessible communication channel capable of high bandwidth and low bit error ratio performance, at relatively low cost.
MAUs support message traffic at a data rate of 10, 100, or even 1000 Mbit/s. They can provide for driving up to 500m of coaxial trunk cable without the use of a repeater. Additionally, a MAU:
In addition to receiving and transmitting network data, MAUs perform jabber detection, in which they remove from the network any node that continuously transmits for longer than the maximum-length packet. This is done to prevent network disruption. Jabbering indicates a possible problem with the node's NIC.
MAUs also help troubleshoot problems with signal quality and integrity. They can test for signal quality errors, which can detect silent failures in the circuitry, as well as perform link integrity functions, which can detect breaks in wire pairs. Both these tests assist in fault isolation.
Collision detection and loop-back functions direct transfer through the MAU.
In normal mode, the MAU functions as a direct connection between the baseband medium and the data terminal equipment (DTE), enabling message traffic between stations. Data output from the DTE is output to the coaxial trunk medium and all data on the coaxial trunk medium is input to the DTE.
In monitor mode or isolated mode, the MAU functions as a receive-only connection between the baseband medium and the DTE. Data output from the DTE is suppressed and only data on the coaxial trunk medium is input to the DTE. This mode is for observing message traffic.
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.
10BASE2 is a variant of Ethernet that uses thin coaxial cable terminated with BNC connectors to build a local area network.
10BASE5 was the first commercially available variant of Ethernet. The technology was standardized in 1982 as IEEE 802.3. 10BASE5 uses a thick and stiff coaxial cable up to 500 meters (1,600 ft) in length. Up to 100 stations can be connected to the cable using vampire taps and share a single collision domain with 10 Mbit/s of bandwidth shared among them. The system is difficult to install and maintain.
Ethernet over twisted-pair technologies use twisted-pair cables for the physical layer of an Ethernet computer network. They are a subset of all Ethernet physical layers.
Carrier-sense multiple access with collision detection (CSMA/CD) is a medium access control (MAC) method used most notably in early Ethernet technology for local area networking. It uses carrier-sensing to defer transmissions until no other stations are transmitting. This is used in combination with collision detection in which a transmitting station detects collisions by sensing transmissions from other stations while it is transmitting a frame. When this collision condition is detected, the station stops transmitting that frame, transmits a jam signal, and then waits for a random time interval before trying to resend the frame.
Apple Attachment Unit Interface (AAUI) is a mechanical re-design by Apple of the standard Attachment Unit Interface (AUI) used to connect computer equipment to Ethernet. The AUI was popular in the era before the dominance of 10BASE-T networking that started in the early 1990s; the AAUI was an attempt to make the connector much smaller and more user friendly, though the proprietary nature of the interface was also criticized.
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 the seven-layer OSI model of computer networking, the physical layer or layer 1 is the first and lowest layer: the layer most closely associated with the physical connection between devices. The physical layer provides an electrical, mechanical, and procedural interface to the transmission medium. The shapes and properties of the electrical connectors, the frequencies to transmit on, the line code to use and similar low-level parameters, are specified by the physical layer.
10BROAD36 is an obsolete computer network standard in the Ethernet family. It was developed during the 1980s and specified in IEEE 802.3b-1985. The Institute of Electrical and Electronics Engineers standards committee IEEE 802 published the standard that was ratified in 1985 as an additional section 11 to the base Ethernet standard. It was also issued as ISO/IEC 8802-3 in 1989.
The Attachment Unit Interface (AUI) is a physical and logical interface defined in the original IEEE 802.3 standard for 10BASE5 Ethernet and the previous DIX standard. The physical interface consists of a 15-pin D-subminiature connection that provides a path between an Ethernet node's physical signaling and the Medium Attachment Unit (MAU), sometimes also known as a transceiver. An AUI cable may be up to 50 metres long, although frequently the cable is omitted altogether and the MAU and medium access controller MAC are directly attached to one another. On Ethernet implementations without separate MAU and MAC, the AUI is omitted.
The media-independent interface (MII) was originally defined as a standard interface to connect a Fast Ethernet medium access control (MAC) block to a PHY chip. The MII is standardized by IEEE 802.3u and connects different types of PHYs to MACs. Being media independent means that different types of PHY devices for connecting to different media can be used without redesigning or replacing the MAC hardware. Thus any MAC may be used with any PHY, independent of the network signal transmission medium.
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.
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.
Token Ring is a physical and data link layer computer networking technology used to build local area networks. It was introduced by IBM in 1984, and standardized in 1989 as IEEE 802.5. It uses a special three-byte frame called a token that is passed around a logical ring of workstations or servers. This token passing is a channel access method providing fair access for all stations, and eliminating the collisions of contention-based access methods.
Ethernet over Coax (EoC) is a family of technologies that supports the transmission of Ethernet frames over coaxial cable. The Institute of Electrical and Electronics Engineers (IEEE) maintains all official Ethernet standards in the IEEE 802 family.
Telecommunications cable is a type of guided transmission medium. Telecommunications are based on transmitting and receiving modulated waves/signals through a medium. Types of telecommunications cable include: electrical cables when electric current is carried; transmission lines and waveguides when electromagnetic waves are transmitted; optical fibers when light signals are transmitted.
Networking cable is a piece of networking hardware used to connect one network device to other network devices or to connect two or more computers to share devices such as printers or scanners. Different types of network cables, such as coaxial cable, optical fiber cable, and twisted pair cables, are used depending on the network's topology, protocol, and size. The devices can be separated by a few meters or nearly unlimited distances.
The 5-4-3 rule, also referred to as the IEEE way, is a design guideline for Ethernet computer networks covering the number of repeaters and segments on shared-medium Ethernet backbones in a tree topology. It means that in a collision domain there should be at most 5 segments tied together with 4 repeaters, with up to 3 mixing segments. Link segments can be 10BASE-T, 10BASE-FL or 10BASE-FB. This rule is also designated the 5-4-3-2-1 rule with there being two link segments and one collision domain.
Physical media refers to the physical materials that are used to store or transmit information in data communications. These physical media are generally physical objects made of materials such as copper or glass. They can be touched and felt, and have physical properties such as weight and color. For a number of years, copper and glass were the only media used in computer networking.
3Com 3c509 is a line of Ethernet IEEE 802.3 network cards for the ISA, EISA, MCA and PCMCIA computer buses. It was designed by 3Com and put on the market in 1992, followed by the improved version 3c509B in 1994.