Local Area Network, LAN, is a data communications network connecting terminals, computers, and printers within a building or other geographically limited areas (Haugdahl, 1999, p. 76). These devices may be connected through wired cables or wireless links. LAN is usually owned by an individual or a single entity such as an organization, and the users communicate with each other by sending e-mail or by chatting. In a LAN technology, applications are stored in the LAN server (Haugdahl, 1999, p. 76), allowing the users to exchange resources with each other at the LAN server. LANs can transmit data at a rate faster than data transferred over a telephone line, and can also be connected to other LANs. The major LAN technologies are Ethernet and Token Ring. This paper discussed these two technologies in detail.
Introduction Ethernet is by far the most widely used Local Area Networking, LAN, technology used in the world today. Ethernet was the brainchild of Bob Metcalfe and David Boggs (Haugdahl, 1999, p 77) The standard was created at Xerox Palo Alto Research Centre, PARC in 1973 (Haugdahl, 1999, p. 77), for networking a group of computers that could all use a new Laser printer that Xerox had made. The original version of the Ethernet operated at 2.9 Mbps (Haugdahl, 1999, p. 77), a speed that was chosen because it was a multiple of the clock speed of the original Alto computer created by Xerox in 1972 as a personal computer targeted at research.
The original Ethernet standard was developed over the next few years, and this resulted in a paper Ethernet: Distributed Packet-Switching for Local Computer Networks published in the Communications of ACM, Vol. 19, No. 5, July 1976, pp. 395-404 (Shepard, 2002, p. 84). Later a consortium of three companies Digital Equipment Corporation, Intel, and Xerox, further developed the Ethernet II or the DIX standard (Mueller & Ogletree, 2003, p. 207). These companies used the networking technology to add networking capabilities to their product line. Ethernet has adapted over the years running on newer devices and running media and can now run on coaxial cables, twisted-pair wiring and fiber-optic coupling (Mueller & Ogletree, 2003, p. 207).
Purpose and Function The initial place for the usage of Ethernet was for connecting office equipments, as is seen above. The standard is pretty much an international standard for this purpose even in the present days. Ethernet is basically a bus structure in which all the signals are sequentially carried on a single wire. The Ethernet standard extends only over hardware and signal levels (Mueller & Ogletree, 2003, p. 207) An Ethernet network can operate under a variety of network protocols (Mueller & Ogletree, 2003, p. 207); it is even possible to support two different network protocols simultaneously on an Ethernet cable.
Accepted places for usage Ethernet has established itself as the de facto standard for PC networks (Mueller & Ogletree, 2003, p. 207). It has become the most widely used communications medium. Due to its present wide acceptance, Ethernet has also been suggested for use in many diverse application fields such as automations, and even embedded systems (Mueller & Ogletree, 2003, p. 208).
Pros and Cons
Following are the advantages with Ethernet
Following are the disadvantages with Ethernet
Market share Ethernet dominates over 90 percent of the installed networks worldwide (Ballew, 1997, p. 34). Ethernet networks are used in all major industries where the requirement for high-speed reliable communications is a necessity.
Current level of implementation There are three types of Ethernet, primarily distinguished from one another by speed:
Introduction Token Ring is the second most widely used Local Area network, LAN, technology after Ethernet. IBM originally developed the Token Ring in 1970. The credit for the technology however goes to a fellow named Olaf Soderblum, who developed the token ring passing network to connect IBM mainframes in Sweden (Shipley, 2002, p. 24). However, the IBM Token Ring Network, TRN, did not appear on the scene until 1985, when the protocol was standardized by IEEE as 802.5 with a speed of 4Mbps (Shipley, 2002, p. 24).
Soon IBM front end processors, such as the IBM 3745s, were shipped with Token Ring interfaces (Shipley, 2002, p. 24). At the time Token Ring provided a fast LAN medium, and was an immediate success with IBM customers, primarily because aside form PC Net, it was the only LAN that IBM really endorsed at the time. The market share of Token Ring was almost 35% till the middle 1990s (Shipley, 2002, p. 24), even though it was an expensive alternative to the Ethernet.
Purpose and Function Token Ring is much more suitable than Ethernet for delay sensitive applications like the IBM Systems Network Architecture, SNA. Token Ring is also recommended for image applications (Shipley, 2002, p. 24)
Accepted places for usage Token Ring LANs, like Ethernet LANs are common in office environments, linking personal computers for the purpose of data file transfer, electronic messaging, mainframe computer interaction and file sharing. Token Ring is the best choice for a framework if the performance of the network is the most important concern and not the network up time (Mueller & Ogletree, 2003, p. 210).
Pros and Cons
Following are the advantages with Token Rings
Following are the disadvantages with Token Rings
Market share While Token ring networks are not nearly as plentiful as Ethernet Networks, they are found at most major data centers running IBM mainframes. The reason for this is because Token ring networks are more expensive to implement than Ethernet networks (Ballew, 1997, p. 34).
Current level of implementation Token Ring, as is mentioned above, is a set of network standards developed by IBM that define a complete network system. The standard is completely incompatible with Ethernet and is considered as its competitor. Token Ring networks use a Ring topology, most commonly today as a star ring. The topologies here are wired into a star configuration using shielded twisted pair cable or unshielded twisted pair cable. The networks are classified into: small movable networks that support up to 96 nodes and 12 Multi-station Access Units, MAU and, large non-movable networks that support up to 260 nodes and 30 MAUs (Barrett & King, 2005, p. 136-137).
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