You have been asked to assess the LAN at a popular, but cash-strapped children\'

Question

You have been asked to assess the LAN at a popular, but cash-strapped children's museum. Visitors have complained that the video kiosk exhibits, which obtain their content from a server on the local network, are slow to respond and sometimes stall out. Meanwhile, museum staff members often wait several minutes to access large files or retrieve Web pages. The museum's IT manager confesses that he hasn't had the time or money to redesign the LAN, which was installed in 1999. It uses small, outdated switches and routers and only delivers 10-Mbps throughput to each client. The IT manager feels confident that he can convince management to support a network upgrade because it's critical to continuing operations. He says the most important parts of the network are the 10 workstations that supply multimedia content to the exhibits, though it's also important for the seven office employees to perform their jobs efficiently. He adds that the museum's connection to its ISP was just upgraded, so it's only the LAN that needs to be changed. What kind of LAN will you design for this company? Describe its backbone, its physical and logical topologies, what access method it will use, and what media and throughputs you recommend.

Explanation / Answer

>Because of all workstations, video kiosks and other related equipment are located in same building and we don't have to connect to our network other locations as well, designing a LAN (Local Area Network) will be the best solution in this case. For this reason I would use a LAN hybrid topology - the star-wired bus formation. In a star-wired bus topology, groups of workstations are star-connected to connectivity devices and then networked via a single bus. With this design, I could cover longer distances and easily interconnect or isolate different network segments.

>One drawback is that this option is more expensive than using the star topology alone because it requires more cabling and potentially more connectivity devices. However, compared with the benefits, these drawbacks are negligible. The star-wired bus topology forms the basis for modern Ethernet networks, which commonly use switches or routers as the connectivity devices.
>Regarding the logical topology, I would use a bus logical topology. Networks that use either the star or star-wired bus physical topologies also result in a bus logical topology. However, it is not necessarily to match network's logical topology with its physical topology. The fact that all nodes connected to a bus network can communicate directly via broadcast transmissions makes them part of a single broadcast domain.
>As a backbone, I would use a parallel backbone, which is the most robust type of network backbone. The switch is connected to the router by two cables, and the two routers are also connected by two cables. The most significant advantage of using a parallel backbone is that its redundant links ensure network connectivity to any area of the enterprise. Parallel backbones are more expensive than other enterprise-wide topologies because they require much more cabling than the others. However, they make up for the additional cost by offering increased performance and better fault tolerance.
>AS a throughput, I would use Ethernet, which is a flexible technology that can run on a variety of network media and offers excellent throughput at a reasonable cost. Because of its many advantages Ethernet is, by far, the most popular network technology used on modern LANs. Its speed and reliability continue to improve.
>As an access method, I would use CSMA/CD (Carrier Sense Multiple Access with Collision Detection). The Ethernet network may be used to provide shared access by a group of attached nodes to the physical medium which connects the nodes.

>These nodes are said to form a Collision Domain. All frames sent on the medium are physically received by all receivers; however the Medium Access Control (MAC) header contains a MAC destination address which ensures only the specified destination actually forwards the received frame. The other computers all discard the frames which are not addressed to them.

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