Take Home Exam Three – BD350

These questions are meant to be answered with either written paragraphs, mathematical solutions or diagrams, depending on what you think is appropriate. For questions in multiple parts, write the answer to each part in a separate line or paragraph.

1. 5 points – What is the name of the technique that temporarily delays outgoing acknowledgments so that they can be hooked onto the next outgoing data frame? Describe how it works.

2. 5 Points – How is congestion control handled in frame relay networks? Explain.

3. 15 Points – How does GSM differ from CDMA? Explain in detail.

4. 15 points – Suppose machines A and B are on a local ATM network. As we know, each ATM cell is 53 bytes in length (including header). If a socket (port 3456) on machine A wanted to send 600 bytes of data to machine B, would the IP layer on machine A fragment the IP packet? Why or why not?

5. 15 points – Suppose machines A and B are each running a single groupware application like a shared whiteboard using two Windows winsock socket connections. Machine A is sending a large image, e.g. approximately 2MB, to machine B. The sockets have only 8KB of buffer memory and therefore the sender has to flush the buffer (thus sending TCP PDUs) prior to accepting all the data from the application. Describe what happens at the receiving side in as much detail as you can, including how the application should process the data stream.

6. 15 Points – In your opinion, which might be better for downloading data, a cable modem or a DSL line? Discuss the issues.

7. 10 Points – Explain how the SONET works. Include a discussion of how it multiplexes and bandwith/throughput.

8. 20 Points – In Figure 7.14 frames are generated at node A and sent to node C through node B. Determine the minimum transmission rate required between nodes B and C so that the buffers of node B are not flooded, based on the following:

a) The data rate between A and B is 8000 kbps

b) The propagation delay is 8 ms/km for both lines

c) There are full duplex lines between the nodes

d) All data frames are 1500 bytes long; ACK frames are separate frames of negligible length

e) Between A and B, a sliding window protocol with window size of 16 is used

f) Between B and C, stop and wait is used

g) There are no errors (twisted bits).

h) Hint: In order not to flood the buffers of B, the average number of frames entering and leaving B must be the same over a long interval