|
SMDS
Switched Multi-megabit Data Service (SMDS) was a connectionless service used to connect LANs, MANs and WANs to exchange data, in early 1990s. In Europe, the service was known as Connectionless Broadband Data Service (CBDS). SMDS was specified by Bellcore, and was based on the IEEE 802.6 metropolitan area network (MAN) standard, as implemented by Bellcore, and used cell relay transport, Distributed Queue Dual Bus layer-2 switching arbitrator, and standard SONET or G.703 as access interfaces. It is a switching service that provides data transmission in the range between 1.544 Mbit/s (T1 or DS1) to 45 Mbit/s (T3 or DS3). SMDS was developed by Bellcore as an interim service until Asynchronous Transfer Mode matured. SMDS was notable for its initial introduction of the 53-byte cell and cell switching approaches, as well as the method of inserting 53-byte cells onto G.703 and SONET. In the mid-1990s, SMDS was replaced, largely by Frame Relay Frame Relay is a standardized wide are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cell Relay
In computer networking, cell relay refers to a method of statistical multiplexing, statistically multiplexing small fixed-length packet (information technology), packets, called "cells", to transport data between computers or kinds of network equipment. It is a Reliability (computer networking), reliable, connection-oriented packet switching, packet switched data communications protocol. Transmission Rates Cell relay bit rate, transmission rates usually are between 56 kbit/s and several gigabits per second. Asynchronous Transfer Mode, ATM, a particularly popular form of cell relay, is most commonly used for home Digital subscriber line, DSL connections, which often runs between 128 kbit/s and 1.544 Mbit/s (Digital Signal 1, DS1), and for high-speed backbone connections (OC-3 and faster). Cell relay protocols have neither flow control (data), flow control nor error correction capability, are information-content independent, and correspond only to layers one and two of the Open Sys ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Connectionless
Connectionless communication, often referred to as CL-mode communication,Information Processing Systems - Open Systems Interconnection, "Transport Service Definition - Addendum 1: Connectionless-mode Transmission", International Organization for Standardization, International Standard 8072/AD 6, December 1986. is a data transmission method used in packet switching networks in which each data unit is individually addressed and routed based on information carried in each unit, rather than in the setup information of a prearranged, fixed data channel as in connection-oriented communication. Attributes Under connectionless communication between two network end points, a message can be sent from one end point to another without prior arrangement. The device at one end of the communication transmits data addressed to the other, without first ensuring that the recipient is available and ready to receive the data. Some protocols allow for error correction by requesting retransmission. Int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metropolitan Area Network
A metropolitan area network (MAN) is a computer network that interconnects users with computer resources in a geographic region of the size of a metropolitan area. The term MAN is applied to the interconnection of local area networks (LANs) in a city into a single larger network which may then also offer efficient connection to a wide area network. The term is also used to describe the interconnection of several LANs in a metropolitan area through the use of point-to-point connections between them. History By 1999, local area networks (LANs) were well established and providing data communication in buildings and offices. For the interconnection of LANs within a city, businesses relied primarily on the public switched telephone network. But while the telephone network was able to support the packet-based exchange of data that the various LAN protocols implemented, the bandwidth of the telephone network was already under heavy demand from circuit-switched voice, and the teleph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wide Area Network
A wide area network (WAN) is a telecommunications network that extends over a large geographic area. Wide area networks are often established with leased telecommunication circuits. Businesses, as well as schools and government entities, use wide area networks to relay data to staff, students, clients, buyers and suppliers from various locations around the world. In essence, this mode of telecommunication allows a business to effectively carry out its daily function regardless of location. The Internet may be considered a WAN. Design options The textbook definition of a WAN is a computer network spanning regions, countries, or even the world. However, in terms of the application of communication protocols and concepts, it may be best to view WANs as computer networking technologies used to transmit data over long distances, and between different networks. This distinction stems from the fact that common local area network (LAN) technologies operating at lower layers of the O ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IEEE 802
IEEE 802 is a family of Institute of Electrical and Electronics Engineers (IEEE) standards for local area networks (LAN), personal area network (PAN), and metropolitan area networks (MAN). The IEEE 802 LAN/MAN Standards Committee (LMSC) maintains these standards. The IEEE 802 family of standards has had twenty-four members, numbered 802.1 through 802.24, with a working group of the LMSC devoted to each. However, not all of these working groups are currently active. The IEEE 802 standards are restricted to computer networks carrying variable-size packets, unlike cell relay networks, for example, in which data is transmitted in short, uniformly sized units called cells. Isochronous signal networks, in which data is transmitted as a steady stream of octets, or groups of octets, at regular time intervals, are also outside the scope of the IEEE 802 standards. The number 802 has no significance: it was simply the next number in the sequence that the IEEE used for standards projects. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Metropolitan Area Network
A metropolitan area network (MAN) is a computer network that interconnects users with computer resources in a geographic region of the size of a metropolitan area. The term MAN is applied to the interconnection of local area networks (LANs) in a city into a single larger network which may then also offer efficient connection to a wide area network. The term is also used to describe the interconnection of several LANs in a metropolitan area through the use of point-to-point connections between them. History By 1999, local area networks (LANs) were well established and providing data communication in buildings and offices. For the interconnection of LANs within a city, businesses relied primarily on the public switched telephone network. But while the telephone network was able to support the packet-based exchange of data that the various LAN protocols implemented, the bandwidth of the telephone network was already under heavy demand from circuit-switched voice, and the teleph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Distributed-queue Dual-bus Network
In telecommunication, a distributed-queue dual-bus network (DQDB) is a distributed multi-access network that (a) supports integrated communications using a dual bus and distributed queuing, (b) provides access to local or metropolitan area networks, and (c) supports connectionless data transfer, connection-oriented data transfer, and isochronous communications, such as voice communications. IEEE 802.6 is an example of a network providing DQDB access methods. Concept of operation The DQDB Medium Access Control ( MAC) algorithm is generally credited to Robert Newman who developed this algorithm in his PhD thesis in the 1980s at the University of Western Australia. To appreciate the innovative value of the DQDB MAC algorithm, it must be seen against the background of LAN protocols at that time, which were based on broadcast (such as ethernet IEEE 802.3) or a ring (like Token Ring IEEE 802.5 and FDDI). The DQDB may be thought of as two token rings, one carrying data in each directio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SONET
Synchronous optical networking (SONET) and synchronous digital hierarchy (SDH) are standardized protocols that transfer multiple digital bit streams synchronously over optical fiber using lasers or highly coherent light from light-emitting diodes (LEDs). At low transmission rates data can also be transferred via an electrical interface. The method was developed to replace the plesiochronous digital hierarchy (PDH) system for transporting large amounts of telephone calls and data traffic over the same fiber without the problems of synchronization. SONET and SDH, which are essentially the same, were originally designed to transport circuit mode communications (e.g., DS1, DS3) from a variety of different sources, but they were primarily designed to support real-time, uncompressed, circuit-switched voice encoded in PCM format. The primary difficulty in doing this prior to SONET/SDH was that the synchronization sources of these various circuits were different. This meant that each ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asynchronous Transfer Mode
Asynchronous Transfer Mode (ATM) is a telecommunications standard defined by American National Standards Institute (ANSI) and ITU-T (formerly CCITT) for digital transmission of multiple types of traffic. ATM was developed to meet the needs of the Broadband Integrated Services Digital Network as defined in the late 1980s, and designed to integrate telecommunication networks. It can handle both traditional high-throughput data traffic and real-time, low-latency content such as telephony (voice) and video.ATM Forum, The User Network Interface (UNI), v. 3.1, , Prentice Hall PTR, 1995, page 2. ATM provides functionality that uses features of circuit switching and packet switching networks by using asynchronous time-division multiplexing.McDysan (1999), p. 287. In the OSI reference model data link layer (layer 2), the basic transfer units are called '' frames''. In ATM these frames are of a fixed length (53 octets) called ''cells''. This differs from approaches such as Internet Pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Frame Relay
Frame Relay is a standardized wide area network (WAN) technology that specifies the physical and data link layers of digital telecommunications channels using a packet switching methodology. Originally designed for transport across Integrated Services Digital Network (ISDN) infrastructure, it may be used today in the context of many other network interfaces. Network providers commonly implement Frame Relay for voice (VoFR) and data as an encapsulation technique used between local area networks (LANs) over a WAN. Each end-user gets a private line (or leased line) to a Frame Relay node. The Frame Relay network handles the transmission over a frequently changing path transparent to all end-user extensively used WAN protocols. It is less expensive than leased lines and that is one reason for its popularity. The extreme simplicity of configuring user equipment in a Frame Relay network offers another reason for Frame Relay's popularity. With the advent of Ethernet over fiber optics, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
