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(Kommer)

Oppgaver uke 45:

1:

Use the client and server code from the INF1060 web page (look under Eksempelprogrammer -> client-server-example). Download them for your tests.

Change the port number in client and server to one of your own choice. Use one terminal window to log in to smaragd, and another to log in to diamant (run ssh smaragd and ssh diamant in two terminals). Compile client and server code. Start the server on smaragd. after that start the client on diamant machine. Check whether they talk with each other.

2:

Change server and client in such a way that you can give them a port number on the command line.

3:

Change the client in such a way, that you can give it a server name and the server port on the command line. Try to run the server on another machine than smaragd.

4:

Check the man pages of all functions that are used in the programs in exercise 1 - exercise 3, and make all of them safer, by checking their return code.

5:

Assume that you have a sender that wants to send data packets to a receiver. The connection that is used is not lossless, so that some of the packets that you send are lost. Propose a method (a protocol) that sender and receiver can use to ensure that all packets arrive.

Hint: The receiver must in one way or another confirm the reception of packets.

6:

Does your answer to exercise 5 guarantee that all packets arrive in the sending order? If not, how can you add that?

7:

Assume that you have to send a packet of 1000 bit length over a data channel that is 2000 km long. Assume that the signal travels approximately at the speed of light, 300.000 km/s. How long does it take from the start of sending the packet to the end of receiving the packet?

  1. the bandwidth of the data channel is 10 Mbit/s
  2. the bandwidth of the data channel is 10 Gbit/s

Hint: You need time for putting the packet onto the channel, and time for moving a bit through the channel.

8:

How does the answer of exercise 7 fit with the expression that the speed of the channel in example b is 1000 times bigger than the speed of the channel in example a?

9:

Propose an application layer protocol on top of TCP for a distributed, turn-based game between two players, such as chess (or GO, nine men's morris, battleships, stratego, ...).

10:

How would you write programs (client and server) that can be used to test the bandwidth between two machines? Explain what information your measurements gives you specifically.

Hint: Consider layer processing.