Computing 205/406 & IT8

Tutorial #8

1. What is the minimum size (in bytes) of an IP datagram which contains exactly one byte of data? (N: trick question)

2. What are the three characteristics of datagram delivery in the Internet?

3. Consider[1] a machine with two physical network connections, and two IP addresses, I(1) and I(2). Is it possible for that machine to receive a datagram destined for I(2) over the network with address I(1)? Explain.

4. play[2] detective: after monitoring IP traffic on a LAN for 10 minutes one evening, someone notices that all frames destined for machine A carry IP datagrams that have destination equal to A's IP address, while all frarnes destined for machine B carry IP datagrams with destination not equal to B's address. Explain.

5. Is[3] it possible to address a datagram to a router's (IP gateway's) IP address? Does it make sense to do so?

6. The following are the output of two runs of the traceroute command, one looking from Bendigo towards the rest of the lnternet via La Trobe, Bundoora, and the other from outside La Trobe looking towards Bendigo. Traceroute is used to discover the route a datagram would take in the Internet. This will be further explained in the tutorial.

   12 ltu.gw.au ( 139.130.8.2) 252 ms 273 ms 123 ms
   13 149.144.1.2 (149.144.1.2) 398 ms 149 ms 273 ms
   14 r-itsbgo.bendigo.latrobe.edu.au (149.144.2.254) 531 ms * 408 ms
   15 busfddi0.bendigo.latrobe.edu.au (149.144.10.1) 244 ms * 273 ms
   16 ironbark (149.144.20.60) 316 ms 279 ms 480 ms
   
   1 149.144.20.254(149.144.20.254) 3ms 3ms 3ms
   2 itsfddi0.bendigo.latrobe.edu.au (149.144.10.254) 3 ms 4 ms 5 ms
   3 r-bgowan.bendigo.latrobe.edu.au (149.144.2.1) 6 ms 4 ms 10 ms
   4 Itu.gw.au 149.144.1.1 (149.144.1.1) 36 ms 32 ms 32 ms
   5 national.gw.au(139.130.8.1) 269ms 304ms 297ms
   

   1. Can you see where the large delays occur in datagram delivery?
   2. Can you use this information to draw a diagram of the topology of the Internet in our region?