|
Token Passing
On a local area network, token passing is a channel access method where a packet called a ''token'' is passed between nodes to authorize that node to communicate. In contrast to polling access methods, there is no pre-defined "master" node. The most well-known examples are IBM Token Ring and ARCNET, but there were a range of others, including FDDI (Fiber Distributed Data Interface), which was popular in the early to mid 1990s. Token passing schemes degrade deterministically under load, which is a key reason why they were popular for industrial control LANs such as MAP, (Manufacturing Automation Protocol). The advantage over contention based channel access (such as the CSMA/CD of early Ethernet), is that collisions are eliminated, and that the channel bandwidth can be fully utilized without idle time when demand is heavy. The disadvantage is that even when demand is light, a station wishing to transmit must wait for the token, increasing latency. Some types of token passing s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Local Area Network
A local area network (LAN) is a computer network that interconnects computers within a limited area such as a residence, campus, or building, and has its network equipment and interconnects locally managed. LANs facilitate the distribution of data and sharing network devices, such as printers. The LAN contrasts the wide area network (WAN), which not only covers a larger geographic distance, but also generally involves Leased line, leased telecommunication circuits or Internet links. An even greater contrast is the Internet, which is a system of globally connected business and personal computers. Ethernet and Wi-Fi are the two most common technologies used for local area networks; historical network technologies include ARCNET, Token Ring, and LocalTalk. Cabling Most wired network infrastructures utilize Category 5 cable, Category 5 or Category 6 cable, Category 6 twisted pair cabling with RJ45 (telecommunications), RJ45 compatible terminations. This medium provides physical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Channel Access Method
In telecommunications and computer networks, a channel access method or multiple access method allows more than two terminals connected to the same transmission medium to transmit over it and to share its capacity. Examples of shared physical media are wireless networks, bus networks, ring networks and point-to-point links operating in half-duplex mode. A channel access method is based on multiplexing, which allows several data streams or signals to share the same communication channel or transmission medium. In this context, multiplexing is provided by the physical layer. A channel access method may also be a part of the multiple access protocol and control mechanism, also known as medium access control (MAC). Medium access control deals with issues such as addressing, assigning multiplex channels to different users and avoiding collisions. Media access control is a sub-layer in the data link layer of the OSI model and a component of the link layer of the TCP/IP mod ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polling (computer Science)
Polling, or interrogation, refers to actively sampling the status of an external device by a client program as a synchronous activity. Polling is most often used in terms of input/output (), and is also referred to as polled or software-driven . A good example of hardware implementation is a watchdog timer. Description Polling is the process where the computer or controlling device waits for an external device to check for its readiness or state, often with low-level hardware. For example, when a printer is connected via a parallel port, the computer waits until the printer has received the next character. These processes can be as minute as only reading one bit. This is sometimes used synonymously with ' busy-wait' polling. In this situation, when an operation is required, the computer does nothing other than check the status of the device until it is ready, at which point the device is accessed. In other words, the computer waits until the device is ready. Polling also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Token Ring
Token Ring is a Physical layer, 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 Standards Association, IEEE 802.5. It uses a special three-byte frame (networking), frame called a ''token'' that is passed around a logical ''ring'' of workstations or server (computing), servers. This token passing is a channel access method providing fair access for all stations, and eliminating the collision (telecommunications), collisions of contention (telecommunications), contention-based access methods. Following its introduction, Token Ring technology became widely adopted, particularly in corporate environments, but was gradually eclipsed by newer iterations of Ethernet. The last formalized Token Ring standard that was completed was Gigabit Token Ring (IEEE 802.5z), published on May 4, 2001. History A wide range of different local area network technologies were developed in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ARCNET
Attached Resource Computer NETwork (ARCNET or ARCnet) is a communications protocol for local area networks. ARCNET was the first widely available networking system for microcomputers and it became popular in the 1980s for office automation tasks. It was later applied to embedded systems where certain features of the protocol are especially useful. History Development ARCNET was developed by principal development engineer John Murphy, at Datapoint Corporation in 1976 under Victor Poor, and announced in 1977. It was originally developed to connect groups of their Datapoint 2200 terminals to talk to a shared 8" floppy disk system. It was the first loosely coupled LAN-based clustering system, making no assumptions about the ''type'' of computers that would be connected. This was in contrast to contemporary larger and more expensive computer systems such as DECnet or IBM's SNA, where a homogeneous group of similar or proprietary computers were connected as a cluster. The tok ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
FDDI
Fiber Distributed Data Interface (FDDI) is a standard for data transmission in a local area network. It uses optical fiber as its standard underlying physical medium. It was also later specified to use copper cable, in which case it may be called CDDI (Copper Distributed Data Interface), standardized as TP-PMD (Twisted-Pair Physical Medium-Dependent), also referred to as TP-DDI (Twisted-Pair Distributed Data Interface). FDDI was effectively made obsolete in local networks by Fast Ethernet which offered the same 100 Mbit/s speeds, but at a much lower cost and, from 1998 on, by Gigabit Ethernet due to its speed, even lower cost, and ubiquity. Description FDDI provides a 100 Mbit/s optical standard for data transmission in local area network that can extend in length up to . Although FDDI logical topology is a ring-based token network, it did not use the IEEE 802.5 Token Ring Communications protocol, protocol as its basis; instead, its protocol was derived from the IE ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Manufacturing Automation Protocol
Manufacturing Automation Protocol (MAP) was a computer network standard released in 1982 for interconnection of devices from multiple manufacturers. It was developed by General Motors to combat the proliferation of incompatible communications standards used by suppliers of automation products such as programmable controllers.J. David Irwin ''The industrial electronics handbook'', CRC Press, 1997 , Chapter 19 By 1985 demonstrations of interoperability were carried out and 21 vendors offered MAP products. In 1986 the Boeing corporation merged its ''Technical Office Protocol'' with the MAP standard, and the combined standard was referred to as "MAP/TOP". The standard was revised several times between the first issue in 1982 and MAP 3.0 in 1987, with significant technical changes that made interoperation between different revisions of the standard difficult. Although promoted and used by manufacturers such as General Motors, Boeing, and others, it lost market share to the contempor ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Contention (telecommunications)
In statistical time division multiplexing, contention is a media access method that is used to share a broadcast medium. In contention, any computer in the network can transmit data at any time (first come-first served). This system breaks down when two computers attempt to transmit at the same time. This is known as a collision. To avoid collisions, a carrier sensing mechanism is used. Here each computer listens to the network before attempting to transmit. If the network is busy, it waits until network quiets down. In carrier detection, computers continue to listen to the network as they transmit. If computer detects another signal that interferes with the signal it is sending, it stops transmitting. Both computers then wait for a random amount of time and attempt to transmit. Contention methods are most popular media access control method on LANs. Collision detection and recovery One method to handle collisions in a contention based system is to optimize collision detection ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bandwidth (computing)
In computing, bandwidth is the maximum rate of data transfer across a given path. Bandwidth may be characterized as network bandwidth, data bandwidth, or digital bandwidth. This definition of ''bandwidth'' is in contrast to the field of signal processing, wireless communications, modem data transmission, digital communications, and electronics, in which ''bandwidth'' is used to refer to the signal bandwidth measured in hertz, meaning the frequency range between lowest and highest attainable frequency while meeting a well-defined impairment level in signal power. The actual bit rate that can be achieved depends not only on the signal bandwidth but also on the noise on the channel. Network capacity The term ''bandwidth'' sometimes defines the net bit rate ''peak bit rate'', ''information rate'', or physical layer ''useful bit rate'', channel capacity, or the maximum throughput of a logical or physical communication path in a digital communication system. For example, bandwi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Latency (engineering)
Latency, from a general point of view, is a time delay between the Causality, cause and the effect of some physical change in the system being observed. Lag (video games), Lag, as it is known in Gaming culture, gaming circles, refers to the latency between the input to a simulation and the visual or auditory response, often occurring because of network delay in online games. The original meaning of “latency”, as used widely in psychology, medicine and most other disciplines, derives from “latent”, a word of Latin origin meaning “hidden”. Its different and relatively recent meaning (this topic) of “lateness” or “delay” appears to derive from its superficial similarity to the word “late”, from the old English “laet”. Latency is physically a consequence of the limited velocity at which any Event (relativity), physical interaction can propagate. The magnitude of this velocity is always less than or equal to the speed of light. Therefore, every physical s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ITU-T
The International Telecommunication Union Telecommunication Standardization Sector (ITU-T) is one of the three Sectors (branches) of the International Telecommunication Union (ITU). It is responsible for coordinating Standardization, standards for telecommunications and Information Communication Technology, such as X.509 for cybersecurity, Y.3172 and Y.3173 for machine learning, and H.264/MPEG-4 AVC for video compression, between its Member States, Private Sector Members, and Academia Members. The World Telecommunication Standardization Assembly (WTSA), the sector's governing conference, convenes every four years. ITU-T has a permanent Secretariat (administrative office), secretariat called the Telecommunication Standardization Bureau (TSB), which is based at the ITU headquarters in Geneva, Switzerland. The current director of the TSB is Seizo Onoe (of Japan), whose 4-year term commenced on 1 January 2023. Seizo Onoe succeeded Chaesub Lee of South Korea, who was director from 1 J ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
