Networking case-projects 4

Case Project 4-1 During the design of most real-world networks, you’ll discover that using more than one type of networking medium is common. The usual reasons for needing more than one type of medium include the following:

  • Two or more areas must be interconnected, and the distance separating them is greater than the maximum segment length for the type of medium used in (or best suited for) each area.

  • A connection must pass through a high-interference environment (across some large transformers, near heavy-duty electrical motors, and so on). Failure to use a different type of medium increases the risk of impeding data flow. This reason is especially common for choosing fiber-optic cable or wireless in many networks, particularly when connecting floors in an office building and the only available pathway is the elevator shaft.

  • Certain parts of an inter-network might have to carry more traffic than other parts. Typically, the segment where traffic aggregates is the backbone, a common cable segment that interconnects subsidiary networks. (Think of a tree trunk as the backbone and its major branches as cable segments.) Often, a higher-capacity cable is used for a backbone (for example, fiber-optic cable or Cat 6 cable rated for Gigabit Ethernet), along with a higher-speed networking technology for attachments to the backbone. This arrangement means outlying segments might use conventional 10 or 100 Mbps Ethernet, and the backbone uses 1 Gbps or 10 Gbps Ethernet. Using this information, suggest solutions that involve at least two types, if possible, of networking media to address the following problems:

    • A—XYZ Corp. is planning a new network. Engineers in the design shop must have connections to accountants and salespeople in the front office, but all routes between the two areas must traverse the shop floor, where arc welders and metal-stamping equipment create potent amounts of EMI and RFI. Given that both the design shop and front office use 10BaseT (twisted-pair Ethernet), how might you interconnect these two areas? What medium guarantees immunity from interference?

      • Fiber Optic Cable

    • B—After the front-office network at XYZ Corp. is set up, an accountant realizes that if the loading dock connected to the network, dock workers could log incoming and outgoing shipments and keep the inventory more current. Even though the loading dock is nowhere near the shop floor, the dock is 1100 feet from the front office. What kinds of cable will work to make this connection? What kind would you choose and why?

      • Fiber Optic could be used the whole way. They could have 10gig on that backbone even at 1100feet (there is cable rated for 10Gbps at 550 meters).

    • C—ABC Company occupies three floors in a 10-story building, where the elevator shaft provides the only path to all these floors. In addition, users on the 9th and 10th floors must access a collection of servers on the 8th floor. Explain what kind of connections would work in the elevator shaft. If more than one choice is possible, pick the best option and explain the reasons for your choice. Assuming that interfloor connections might someday need to run at much higher speeds, reevaluate your choice. What’s the best type of medium for open-ended bandwidth needs? Explain your answer.

      • Fiber would be fine for the elevator shaft and could handle a lot of bandwidth in case it’s ever needed in the future. Multiple cables should be run in case one dies, then instead of having to run a cable again the users can simply switch to one of the backup cables. Ethernet can have quite high bandwidth as well, but degrades faster over distance and is more vulnerable to EFI and RFI.

Case Project 4-2 XYZ Corp.’s facilities in Nashua, New Hampshire, are two office buildings 400 feet apart, each with its own LAN. To connect the two networks, you plan to dig a trench and lay cable in conduit between the two buildings. You want to use fiber-optic cable, but your budget-conscious facilities manager wants to use 100 Mbps Ethernet over twisted-pair cable. Which of the following reasons can you use to justify fiber-optic cable in this case, and why?

  • a: Twisted pair won’t span a 400-foot distance.

    • Even cat7 will start to degrade after 100 meters.

  • b: Fiber-optic cable is cheaper and easier to work with than twisted pair.

    • They seem just as easy to work with for me personally and are comparable in price to cat currently (I just checked prices online).

  • c: Twisted pair is a conductive cable and can therefore carry current based on the difference in ground potential between the two buildings.

    • True

  • d: Fiber-optic cable leaves more room for growth and future needs for increased bandwidth than twisted pair does.

    • True

Case Project 4-3 TVBCA has just occupied a historic building in downtown Pittsburgh where 15 employees will work. Because of codes for historic buildings, TVBCA isn’t permitted to run cables inside walls or ceilings. Required result: Employees must be able to share files and printers, as in a typical LAN environment, without using cables.

Optional desired results: Employees must be able to use their laptops or tablets and move freely throughout the office while maintaining a network connection. Because of the size of some computer-aided design (CAD) files employees use often, data transfer speeds should be at least 100 Mbps and the connection should be secure.

Proposed solution: Install an 802.11ac wireless access point and configure each mobile device to connect to the AP with WPA2 encryption. Which of the following results does the proposed solution deliver? Explain your answer.

  • a: The proposed solution delivers the required result and both optional desired results.

  • b: The proposed solution delivers the required result and only one of the two optional desired results.

  • c: The proposed solution delivers the required result but neither optional desired result.

  • d: The proposed solution does not deliver the required result.

This depends on how many employees are going to possibly be transferring the large CAD files at 100Mbps at the same time. It also depends on how large the historical building is, what it’s made out of, and what kind of wireless access point is used. Without knowing those details it’s impossible to create a solution that will be guaranteed to work. It can be done. Additionally, because they can’t run cables in the walls doesn’t mean they can’t run them along the walls. If the cables have to go through doors there are cables small enough to fit in the gaps between the door and the frame.