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1. Whataretworeasonsforusinglayeredprotocols?Whatisonepossibledisadvantageofusinglayeredprotocols?( Problem 10, page 86 of the text book.)

2. A system has an n-layer protocol hierarchy. Applications generate messages of length M bytes. At each of the layers, an h-byte header is added. What fraction of the network bandwidth is filled with headers? (Problem 16, page 87 of the text.)

3. What is the main difference between TCP and UDP? (Problem 17, page 87 of the text book.)

4. The ping program allows you to send a test packet to a given location and see how long it takes to get there and back. Try using ping to see how long it takes to get from your location to several known locations. From these data, plot the one-way transit time over the Internet as a function of distance. It is best to use universities since the location of their servers is known very accurately. For example, berkeley.edu is in Berkeley, California; mit.edu is in Cambridge, Massachusetts; vu.nl is in Amsterdam; The Netherlands; www.usyd.edu.au is in Sydney, Australia; and www.uct.ac.za is in Cape Town, South Africa. Does the response times reflect the physical distance in your experiments? Can we conclude it is always the case? (Problem 33, page 88 of the text book.)

5. An image is 1024 x 768 pixels with 3 bytes/pixel. Assume the image is uncompressed. How long does it take to transmit it over a 56-kbps modem channel? Over a 1-Mbps cable modem? Over a 10-Mbps Ethernet? Over 100-Mbps Ethernet? (Problem 23, page 87 of the text.)