Q1) Make use of the Network below, use Dijkstra's algorithm and compute the shortest path from x to all network nodes. Show how the algorithm works by computing a table similar to the following:
| Step |
N' |
D(v),p(v) |
D(w),p(w) |
D(x),p(x) |
D(y),p(y) |
D(z),p(z) |
| 0 |
u |
2,u |
5,u |
1,u |
|
|
| 1 |
ux |
2,u |
4,x |
|
2,x |
|
| 2 |
uxy |
2,u |
3,y |
|
|
4,y |
| 3 |
uxyv |
|
3,y |
|
|
4,y |
| 4 |
uxyvw |
|
|
|
|
4,y |
| 5 |
uxyvwz |
|
|
|
|
|
Let us define the following notation:
• D(v): cost of the least-cost path from the source node to destination v as of this iteration of the algorithm.
• P(v): previous node (neighbor of v) along the current least-cost path from the source to v.
• N: subset of nodes: v is in N' if the least-cost path from the source to v is definitively known.
Q2) Consider the network shown in Problem P26. Using Dijkstra's algorithm, and showing your work using a table similar to the table shown in QI , do the following:
a. Compute the shortest path from t to all network nodes.
b. Compute the shortest path from u to all network nodes.
c. Compute the shortest path from v to all network nodes.
d. Compute the shortest path from w to all network nodes.
e. Compute the shortest path from y to all network nodes.
f. Compute the shortest path from z to all network nodes.
Q3) The CS department at Saint Andrew University bought new Sun Fire V210 servers. They decided to run a distance-vector protocol for routing between these servers (even though it is a rather small network). They are currently configured as the picture below, with respective edge costs.
The CS staff asked for your help. Write down each step of bdilding the distance vector routing table for 'E' so they can compare it to the output of their implementation.
Q4) From a service perspective, explain by giving two examples what is an important difference between a smmetric-key system and a public-key system?
Q5) Neverland's Immigration Department is to send a sequence of photograph over Ethernet cable for identification purposes, The photograph size is 591x827 pixels, each pixel is 26 bits. The rate of sending is 80 photographs per second. The bandwidth of the channel is 12 Hz. Assuming white thermal noise, using Shannon's formula. calculates what signal-to-noise ratio is required to achieve this capacity?
Q6) For the bit stream 0100110011101010, sketch the waveforms for each of the codes NRZ-L, NRZ-I, Bipolar-AMI, Manchester and Differential Manchester. Assume that the signal level for the preceding bit for NRZ-1 was high; the most recent preceding 1 bit (Bipolar-AMI) has a negative voltage. The previous signal flow from negative to positive voltage in Differential Manchester Digital Encoding Schemes
7) Explain in detail how Data Encryption Standard works with a diagram.
8) What are the differences between message confidentiality, integrity, availability, authentication? Can you have one without the other? Justify your answer by giving an example.