Computer Networks:

1. Basic concept question a) b) c) d) What is the major advantage of layered architecture of the internet? what is the difference between "circuit switching" and "packed switching"? (list at least 3) What does the Shannon capacity have to do with communications? Which of the four modulation techniques (ASK, FSK, PSK, or QAM) is the most susceptible to noise? Defend our answer 2. A typical analog phone line will carry frequencies between 300 Hz and 3300 Hz and has a signal-to- noise ratio of 30 Db a) Will this support a 48 Kbps modern? b) b. Provide two ways to make the channel support such a rate 3. Consider the following network path with 3 links and two store-and-forward packet switches. The speeds and the propagation delays of the links are as indicated in the following picture. Packets flow from left to right. Node that each switch has 1.5MB of memory for ding store-and-forward. We assume there is no processing delay at any switch. 10Gbps 2Gbps 2Gbps 0 1.5MB 1.5 MB 40ms 5ms 10ms a) Assume that the path is completely empty initially. What is the total time required to transmit a 500 KB packet across this path (i.e. the time from the first bit is injected until the last bit emerges)? Assume that someone has just finished injecting a 500KB packet into the first link before you start transmitting your 500KB packet. In this case, what is the total time required to transmit your 500KB packet across the path? What is the maximum number of bits of data this network path carries at any moment? A MP3 file is roughly 5MB, how many MP3 files can the path carry at any moment? b) c)