Essay Sample on Network Topologies: A Brief Description of Each

Posted on April 22, 2011

Free example essay on Network Topologies:

Mesh Topology
In this type of network setup devices are connected with many redundant interconnections between network nodes. In a true mesh topology every node has a connection to every other node in the network. An advantage of this type of topology lies in the fact that it is relatively immune to bottlenecks and channel/mode failures. Allowing data to be rerouted around failed or busy nodes does this. A major disadvantage is high cost due to the high number of interconnections.

Bus Topology
All devices are connected to a central cable, termed a bus or backbone. At each end of this cable is a terminating resistor, or a terminator. A signal gets passed back and forth between workstations and between the terminators. An advantage of this type of topology is that if one workstation fails, it does not affect the entire LAN. Another advantage is that it is easy to implement and cost efficient. A disadvantage to this type of topology is that it a connection to one of the workstations becomes loose, or a cable breaks, the entire cable segment loses connectivity.

Ring Topology
All devices are connected to one another in the shape of a closed loop so that each device is connected directly to two other devices, one on the either side of it. In most cases data flow is in one direction only, with one single node receiving the transmission and relaying it to the next node. The advantage of this topology is that it is rarely subjected to the bottlenecks associated with hierarchical and star configurations. One disadvantage is that a single channel connects all nodes. If a channel fails between two nodes the entire network is lost.

Star Topology
All devices are connected to a central hub. Nodes communicate across the network by passing data through the hub. This topology uses signal splitters in the hub to send out signals in different directions on the cable connections. The advantages to this type of topology are that star topology based hubs can be connected together to extend the network, it is easy to add new workstations, and management and monitoring is not difficult to do. Disadvantages to this system lie in with the hub; if it fails the workstations connected to the hub lose connectivity.

Ethernet is a local-area network (LAN) architecture developed by Xerox Corporation in cooperation with DEC and Intel in 1976. Ethernet uses a bus or star topology and supports data transfer rates of 10 mbps. The Ethernet specification served as the basis for the IEEE 802.3 standard, which specifies the physical and lower software layers. Ethernet uses the CSMA/CD access method to handle simultaneous demands. It is one the most widely implemented and used LAN standards. 100Base-T (Fast Ethernet) supports data transfer rates of 100 Mbps. Gigabit Ethernet supports data rates of 1 gig per second. Ethernets are easy to design and manage and aren’t too costly to implement. Disadvantages lie in the different topologies supported and their individual nuisances.

Token Ring
A token-ring network is a type of network in which all of the computers are arranged in a circle. The token, which is a special bit pattern, travels around the circle. To send a message, a computer catches the token, attaches a message to it, and then lets it continue to travel around the network. Workstations are connected centrally to a Media Access Unit (MAU) and are wired in a star configuration. Advantages of a token-ring network are that cable failures affect only a small number of users, there is equal access for all workstations and limited performance degradation as the network grows. A huge disadvantage is the cost of wiring and connections.

Fiber-distributed data interface- an industry standard covering the transmission of data over fiber-optic links. Fiber optics allows data to flow at very high speeds (100Mbits/sec). High-speed data transmission and multiple uses of the fiber optic solution make give this setup and advantage. One disadvantage is cost and availability in some areas.

A wireless LAN is one in which a mobile user can connect to a local area network through a wireless (radio) type connection. The IEEE 802.11 standard specifies the technologies for wireless LANs. An advantage of wireless networks is that they can be accessed virtually from anywhere. There is a price for this connectivity. Up front costs are higher than most other solutions. There is also a distance limitation of 150 feet. Security could be compromised as well.

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