Sunday, 4 March 2012

Networking, Technology & Topology

Computer networking
 Today we learn about computer networking. Computer networking is connecting a computer with other computers or other devices to enable them to communicate with each other, between computer devices/equipment, transmission media to send/control data/signals, communication devices to transmit/send data from sources to destinations and software.
Network Classification
-LAN – Local Area Network
-WAN - Wide Area Network
-MAN - Metropolitan Area Network
Terminals & Workstation
Normally refers to data sources and destinations.
• E.g
– Personal computers
– Terminals
– Workstations
– Computers
– Automatic teller machines
Next, we learn about transmission media, the physical media used to transmit data in a networked environment.
Network electronic device is devices that controls data transmission from sources to destinations also act as interface between different transmission media or communication protocol. Network software is the information, data or programming used to make it possible for computers to communicate or connect to one another. Network software is used to efficiently share information among computers. At the nodes : involve techniques and protocols to determine rules and procedure to transmit , terminate, translate and to present data and also to control errors. Architecture: blueprint of standards for a network consisting of items such as choice of media, media interfaces, encoding methods, transmission protocols, routing protocols, etc. It is needed to ensure interoperability between various devices and equipment made by different vendors.
Advantages of resource sharing is high reliability, no time constrain, and accessible anytime. Scalability– Computer networks provide an effective mechanism to scale up and provide services to more users at more locations where needed and when needed. Manageability– Networks allow remote resources to be managed effectively (e.g., remote control of telescopes or other resources). Cost - Effectiveness– Networks allow effective implementation of complex distributed systems that must work together (cooperate). Eg., combination of mainframes, workstations, PC’s, networked storage and networked printers. Provide access to needed resources from anywhere at any time. Support collaborative group work independent of location.  After that we learnt about Database access such as other institution, Online shopping, Online Newspaper, on line job/Telecommuting, and Digital libraries.
Later, we learn about networking and topology. Network topology is the study of the arrangement or mapping of the elements (links, nodes, etc.) of a network, especially the physical (real) and logical (virtual) interconnections between nodes. Physical topology, the physical layout of devices on a network or the way that the devices on a network are arranged and how they communicate with each other, the way that the workstations are connected to the network through the actual cables that transmit data, and the physical structure of the network. Logical topology : the mapping of the flow of data between the nodes in the network determines the logical topology of the network the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices.
A linear bus topology consists of a main run of cable with a terminator at each end. All nodes (file server, workstations, and peripherals) are connected to the linear cable. Ethernet and LocalTalk networks use a linear bus topology. Advantages of a Linear Bus Topology,  Easy to connect a computer or peripheral to a linear bus. It requires less cable length than a star topology. Disadvantages Entire network shuts down if there is a break in the main cable. A faulty cable or workstation will take the entire LAN down, the terminators are required at both ends of the backbone cable. It is difficult to identify the problem if the entire network shuts down. Not meant to be used as a stand-alone solution in a large building.
Each of the systems is connected to its respective neighbour forming a ring. The main difference between the bus and ring is that the ring topology does not require termination. Because the systems are connected all together in a loop, there is no beginning and end point as there is with the bus topology. This configuration is seen in Fibre Distributed Data Interface (FDDI) networks.

This configuration is common with twisted pair cable; however, it can also be used with coaxial cable or fibre optic cable. The protocols used with star configurations are usually Ethernet or Local Talk.
A tree (hybrid) topology combines characteristics of linear bus and star topologies. It consists of groups of star-configured workstations connected to a linear bus backbone cable. Tree topologies allow for the expansion of an existing network, and enable schools to configure a network to meet their needs. The advantage is point-to-point wiring for individual segments. Meanwhile the disadvantages are overall length of each segment is limited by the type of cabling used. If the backbone line breaks, the entire segment goes down. More difficult to configure and wire than other topologies.
That’s all we learn today. See you in the next entry.

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