Scenario: Spidola, an organization that manufactures radios, uses many local area networks in its corporate office. Spidola naturally used earlier forms of Ethernet based on hubs when LANs were first becoming popular. The LAN speeds in the corporate office have been upgraded several times over the years, with some groups now using 10 Mbps, and others 100 Mbps. Spidola continues to use hubs to this day, because the network manager, Alan, likes that the price of hubs is significantly lower than that of layer-2 switches, and feels that older technologies are time-tested and proven. The cables for the 100Mbps subnets run to a server room, while the cables for the 10Mbps subnets run to utility closets. Spidola has no wireless access.

The CTO, recognizing the current trends, has asked Alan to upgrade the speed of the network, use more modern technology, and add wireless capabilities. Alan submitted the following proposal.

Network Design

The network staff will interview the managers and technical leads from every internal group to determine what applications they use, and be sure to include the executives in this interview process. Using this information, the network staff will carefully calculate the speeds needed by each group. The staff will then contact various vendors to review their prices through discount negotiations or bid requests, and determine the cheapest devices available to support the speeds necessary for each group. The goal is to minimize purchase cost. This process will take about a year.

During the interview process, the staff will also ask about who needs wireless access, to get a rough number of users that would use it.

Network Implementation

After the technologies and speeds have been designed, some groups will be given 100Mbps speed subnets connected to hubs, which will be placed in the server room. This allows some existing hubs to be reused rather than purchase. Some groups will be given 1Gbps subnets connected to switches, also placed in the server room. If most in a group needs wireless access, their wired access will be removed to save upgrade cost, and all in the group will access the network wirelessly.

Wireless access points will be placed near to groups that need wireless access. If no one needs wireless access in a certain part of the building, no access point will be added. Access points will also be placed around the edges of the building, so that employees can access the network with their laptop at the picnic tables and outdoor areas.

The upgrades will be rolled out one small area at a time, to avoid work disruptions. This process will take about 10 months.

1. Review the network design and implementation proposal given by Alan, then address the following.

a. What elements of Alan's proposal are problematic? Identify them, and explain what the issues are.

b. What elements of Alan's proposal work well? Identify them, and explain why they work well.

3. Alan's proposal has hubs and switches that coexist on the same network. Compare and contrast the characteristics of each type of device with regards to the following aspects:

a. throughput

b. frame collisions

c. frame loss

d. security

e. future growth and speed upgrades

4. The CTO asked for wireless capabilities, and Alan's proposal includes access points to this end.

a. What are two security vulnerabilities that would be easier to exploit on Spidola's new WLAN when compared to Spidola's existing wired LANs?

b. What are three steps that could be taken to mitigate or eliminate these vulnerabilities?

c. What wireless protocol(s) would provide Spidola with fast and secure WLAN access, while being readily available in modern network devices?

5. Now that you have reviewed the characteristics, positives, and negatives of Alan's proposal:

a. Write an alternative proposal that does not exhibit the same issues. The proposal should contain both a network design and a network implementation section, and correct the issues you listed in 1a.

b. Explain specifically why your proposal is better than Alan's, hitting on all of the following topics in your comparison:

Speed

Cost

Network management

Security

Functionality