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.
The Essay on Cd And Data Storage Technology
CD and Data Storage Technology Figure 1 Optical storage techniques make use of the pinpoint precision possible only with laser beams. Alaser uses a concentrated, narrow beam of light, focused and directed with lenses, prisms, and mirrors. The tight focus of the laser beam is possible because the light is all the same wavelength. There are two common types of optical technology. The most widely ...
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.
The Essay on Ethernet Network Frame Time Length
LANs: Introduction & Ethernet 1. Discuss factors that limit speed of operation and range in cables. 2. Discuss the techniques used to enable Ethernet to operate at speeds of 100 Mbps, or more. 3. Consider the transfer of a million bytes of data from one station to another, distance D apart, by means of encapsulation. What is the total elapsed time and effective throughput for the following ...
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 contained to the segment for which it is destined, be it a server, station or workgroup. Switched Ethernet brings new quality to traditional bridged and routed networks. A 10 Mbps or 100 Mbps shared channel can be changed to 10 Mbps or 100 Mbps of dedicated bandwidth. Bridges and routers typically have multiply devices connected to their ports, sharing the available bandwidth.
Switches allow connection between a shared segment (a workgroup) or a dedicated one (a power user or server) to each port. Most importantly, this is accomplished without upgrading any software or hardware already running on the workstations. In addition to that, installing a switch is less complex than a bridge/router configuration; this ease of use makes switching an attractive solution. Ethernet switches break LANs single shared environment a into bunch of parallel dedicated lines that enable smooth efficient network traffic. In addition to that switches provide scalable architecture. A switch port serve as a segment with many stations attached to it or with a single station connected to it.
The Report on Networks
... 4-7 Iink from the tree Unit III Circuit switching vs. packet switching / Packet switched networks – IP – ARP – RARP – DHCP – ... data. Division into traffic classes • Traffic is divided into two classes 1. Synchronous traffic – Traffic is delay sensitive ... Port addressing: Inserting the port address in the header 3. Segmentation and reassembly: Dividing the message into segments and each segment ...
In the former set-up, the segment is a collision domain and the rules of contention based on CSMA/CD are applied. However, to be effective Switching has to be properly implemented. There has to be a clear picture about information traffic. For example, if a number of workstations frequently access a server on the same segment, it would make little point to connect the server to a switch only by one port because only one workstation can be served at a time. On the other hand, connecting the server to a switch using three ports will allow three parallel bit flows to three different workstations in the same segment, tripling the existing bandwidth. Poorly install switch can even worsen traffic situation.
For instance, segments of different departments connected to the same switch will create an overwhelming flow causing congestions because each segment adds its traffic to the entire network. Traffic generated by a particular segment should remain on that segment. In this case traffic is segment specific and there is little point to broadcast in outside. At the same time a switch will greatly speed up information flow if connected to a single resource, say email server, which is accessed by all departments. Each group will have a dedicated link to that server. The usability of the aggregated bandwidth is further augmented by the fact that a switch establishes an instant change of dedicated connections: a direct connection from sales department can immediately turn into the one from accounting. Switching technology will definitely be present networks, allowing more efficient traffic control.
Moreover, switching flexible architecture facilitates migrations to more efficient networks; it cuts down the cost of an upgrade by narrowing down the lines with the most traffic. However, installing switches in an existing network can be only a temporary solution, besides it requires through analysis of existing traffic, which can be altered with time, in turn putting switching advantages to a minimum..
