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1.Your friend is trying to tell you that a router and a switch are basically the same thing, at least as far as setting up a small office / home
1. Your friend is trying to tell you that a router and a switch are basically the same thing, at least as far as setting up a small office / home office network are concerned, and provided you don't count the wireless part. And now he's trying to figure out why the nice Linksys five-port Ethernet switch (model EXZS55W, if that matters) he bought (used, at the flea market) won't let him set up his two laptops, printer and network attached storage device and be able to access the Internet. Your friend is the sort that really does have to see "chapter and verse" on ideas before he'll believe you. Spell it out to him: what really is the difference between the router and the switch, and why can't he just use the switch to do what he wants to?
2. In the meantime, another friend has asked you to consult on their business networking needs. They are setting up a medium-sized technical literature e-publishing company, and they've rented a small campus of three single-story office buildings, each separated from the others by about a hundred feet or so of parking, driveway, trees, and shrubs, etc. Each building will house the people and systems for one group of products, but all must be able to collaborate in a variety of ways. They want a resilient, fault-tolerant network, and they think they want each building to have its own set of servers (for different applications, etc.). About 100 user workstations are planned for each building, which includes wireless access from laptops etc. Access controls on the network should allow for segregation of access to information by location -- only those information assets in building 2 that are declared "public organization-wide" for example should be accessible to workers in the other two buildings. What features does this drive you to consider for the overall network? What do you see as absolutely essential, and what would be good "future-proofing" for growth in capabilities and usage? What features should they look for in the network interfaces in the various computers, laptops, servers, etc., that they will be buying?
3. You've just read about the Stone SuperComputer project, in which under-funded scientists at Los Alamos National Laboratory took a whole roomful of cast-off, obsolete desktop PC/XTs and networked them together(using plain old TCP/IP and SOHO-quality switches, routers, NICs and such) to make a 128-node parallel computing facility. This kind of job requires some incredibly good "handshaking" at just about all layers in the OSI model. (Imagine a user program, which is copied to each of those 128 machines, and all 128 copies of that program are sharing data with each other in some incredibly complex calculation... and you've got the hang of parallel computing!) Discuss how you would think all of the layers of the OSI model might support this. Draw some diagrams if it helps you understand this, or explain it, more clearly.
4. Your local high school has challenged you to help them challenge their students by building such a Stone SuperComputer with them. No, they don't have all 128 of those old PC/XTs sitting around just yet... maybe only a dozen to start with. But if they can make it work with this year's students, they'd love to keep growing it. What sort of network design do you want to recommend that they look at -- knowing that none of them can afford to buy a 128-port switch or router right up front? How could your network grow to accommodate this project? Does allowing / encouraging the use of wireless as well as wired switches and routers help you or only make things more complicated and run slower?
5. For that high school project, you want to help the students figure out how to take each piece of donated equipment and figure out what it can do, and what it cannot. Let's focus on the switches for a moment. What procedure might you lay out for them to determine which switches need to be connected with crossover cables to other switches, and which ones don't? Assuming that the manuals are not readily available for these switches -- and remembering that students don't always read everything they are given! -- how can students test a switch to see if it's working and whether it needs crossover cables or just straight-through patch cables to interconnect?
