Introduction part 1 Essay - 3,071 words

Introduction During last three decades Ethernet has become the most widely deployed internetworking topology in the world. Ethernet, which is the common name for IEEE 802.3 CSMA/CD-carrier sense multiple access, collision detection technology, is the dominant cabling and low-level data delivery standard used in local area networks (LANs). Ethernet technology, developed by Robert Metcalfe and outlined in his 1974 Ph.D. thesis at Harvard University; later it was implemented and further developed as an open standard by DEC, Intel, and Xerox (or DIX)(Loomis 45). The Institute of Electrical and Electronics Engineers (IEEE) described these specifications as formal standard. The term Ethernet was coined by Metcalfe.


The part "ether" describes the main feature of the technology: as the one able to connect different computer systems. Below are some basic Ethernet features: There are several Ethernet technologies: 10 Mbps (million bits per second), to 100 Mbps (Fast Ethernet), and further to 1000Mbps (Gigabit Ethernet) and the latest development 10000 Mbps (10 Gigabit Ethernet). Currently, 10BaseT and 100BaseT (Fast Ethernet) Ethernets are the most common, and both can be built with twisted-pair cabling. Data is transmitted over the network in discrete packets (frames), which are between 64 and 1518 bytes in length (46 to 1500 bytes of data, plus a mandatory 18 bytes of header and cyclical redundancy code [CRC] information). Each device on an Ethernet operates independently and equally, precluding the need for a central controlling device. Ethernet supports a wide array of data types, including TCP/IP, AppleTalk, IPX, and more. To prevent the loss of data, when two or more devices attempt to send packets at the same time, Ethernet detects collisions.


All devices immediately stop transmitting and wait a randomly determined period of time before they attempt to transmit again. Ethernet is the most popular physical layer LAN technology in use today. CIBC World Markets estimates that this year there are 326 million installed Ethernet connections(Caplan ). Ethernet is popular because it strikes a good balance between speed, cost and ease of installation. These benefits, combined with wide acceptance in the computer marketplace and the ability to support virtually all popular network protocols, make Ethernet an ideal networking technology for most computer users today. An international standard, IEEE802.3, technical specification of all aspects of Ethernet design and construction. This standard, first established in 1983, ensures that components supplied by different vendors will work harmoniously together when used on a network. As a result, users enjoy a technology which has been the subject of immense investment over the years from many major semiconductor and network product manufacturers. Switched Ethernet Traditionally, many LAN access methods, like the MAC (Media Access Protocol) protocols for Ethernet, Token Ring and FDDI (Fiber Distributed Data Interface), were characterized by shared environment. Lets take for example a traditional Ethernet LAN, it has a common bus-type design. Workstations are physically attached to this bus through a hub, repeater or concentrator, constituting a broadcast domain.


Every station is capable of receiving all transmissions from all stations, but only in a half-duplex mode. In other words computers on this type of LAN can not talk simultaneously. Still, nodes on an Ethernet network send information strictly observing the following rule: they listen before speaking. Therefore, in Ethernet environment, only one node on the segment is allowed to broadcast at any time due to the CSMA/CD protocol (Carrier Sense Multiple Access/Collision Detection). Though this handles packet collisions, it increases transmission time in two ways. First, if two nodes start transmitting simultaneously, their packets collide, so they both must stop broadcast and wait for better time. Second, once a packet is transmitted from a node, an Ethernet LAN will send any other information until that packet reaches its endpoint.


This often cause LAN congestions. The inefficient pattern described above, along with increased traffic due to ever growing number of network users and amount of data transported between client/server applications, responsible for bandwidth shortages that plague many existing networks. Switching technology is aimed to increase efficiency of the traffic pattern, making current systems more useful. Switching is an intelligent traffic regulator: it forwards information directly from the port of origin to its destination port. Switching not only enhances network performance, it also boosts up flexibility of a network. Switching allows simultaneous links between various ports, by establishing direct lines of communication between origin and destination ports . It proficiently handles network traffic by reducing media sharing - traffic is con ...................................................................................................................................................................................................................................................................................................................................................................

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Essay Tags: fast ethernet, ethernet, segment, traffic, port

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