IST 220 Fall 2009

Homework 1

Due: 10/01/2009

  1. On personal.psu.edu (130.203.28.46), we want to trace the route to cs.berkeley.edu (128.32.125.5)

A. what is the command that should be used?

B. assume the output of the command is:

1. lcs.mit.edu (18.26.0.115) 15ms 16ms 15ms

2. dmc.berkeley.edu (128.32.126.1) 85ms 65ms 100ms

3. cs.berkeley.edu (128.32.125.5) 225ms 228ms 230ms

then

B.1 draw the route from the source host to the dest host

B.2 how many hosts are in the route?

B.3 how many hops are in the route?

B.4 what is the average round-trap time from personal.psu.edu to dmc.berkeley.edu (please consider all the three packets)

  1. Say TRUE or FALSE to the following statements
  1. A signal (i.e., electrical current) can travel through a wire as long as it wants
  2. When wires are put close to each other, parallel pairs suffer from less electrical interference than twisted pairs.
  3. Coaxial cables suffer from less electrical interference than optical fibers.
  4. In a wireless adhoc network, a message (or a packet) sent out by a computer can be received by all the other computers in the network (no matter how far they are from the sender) since radio waves broadcast to everywhere.
  1. Consider a transmission system that transmits message "ER" from one computer to the other.

a. draw the waveform diagram (of the electric current) if we use three possible values of voltages, namely, positive, zero, and negative.

b. draw the waveform diagram if we use only two possible values of voltages, namely, positive and negative, and if we want to send characters as a unit.

  1. Assume the bandwidth for a wire is B=5000HZ

a. if there were no noises on the wire, and there are two possible values of voltages, what is the maximum bit rate enabled by the wire.

b. if there are noises, assume the signal-to-noise ratio is 30 dB, what is the maximum bit rate enabled by the wire.