CSCI 278 : COMPUTER NETWORKS

Instructor : Seung Bae Im

MIDTERM EXAM ----- Spring 2004

 

Closed book, closed notes. Write neatly.

 

Name : _____________________________

 

1.(28 points) Describe the following terms and answer the questions.

(a)    Peer-to-peer layer virtual communications

 

 

 

 

 

 

 

 

 

(b)   nth layer protocol

 

 

 

 

 

 

 

 

(c)    Network protocol architecture, also give an example.

 

 

 

 

 

 

 

 

 

(d)   State why the OSI Model is important?

 

 

 

 

 

 

 

 

(e)    Discuss the overlap of functions between ISO and ITU-T and also discuss how they cooperate.

 

 

 

 

 

 

 

 

 

 

(f)     Discuss the role of IEEE in the arena of network standards.

 

 

 

 

 

 

 

 

 

(g)    Discuss how “Internet” standards are established.

 

 

 

 

 

 

 

 

 

2.(6 points) State the reasons why TCP/IP protocol suite is dominant(used almost everywhere, used on  almost every machine) over all other protocols including OSI protocols. Include the terms: ARPANET, BSD

 

 

 

 

 

 

 

 

 

 

 

 

3.(20 points) Describe/discuss

(a)    Define “Signal bandwidth” and “Channel bandwidth”.

      Also discuss the relationships between the two.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(b)   Discuss how/why a telephone voice channel bandwidth is limited to 300Hz – 3400Hz.

 

 

 

 

 

 

 

 

 

 

 

 

(c)    What is “Crosstalk”?

 

 

 

 

 

 

 

 

(d)   Discuss the significance of Shannon’s Law.

 

 

 

 

 

 

 

4.(20 Points) Answer the questions.

(a)    Describe how “multibit modulation” works.

 

 

 

 

 

 

 

 

 

(b)   What is ISM(Industrial, Scientific, Medical) band?

 

 

 

 

 

 

 

 

 

 

(c)    State why 4B/5B code is more efficient than Manchester code.

 

 

 

 

 

 

 

 

 

(d)   Describe the “Fourier Theorem”.

 

 

 

 

 

 

 

 

 

 

 

 

 

5.(10 points) Show a diagram which illustrates how T-1 carrier multiplexes 24 digitized voices. Also, show the calculation to derive its data rate of 1.544 Mbps. In the calculation, clearly mark each component.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6.(16 points) Discuss/describe

(a)    Draw the protocol diagram(showing layers and sublayers) for the LAN protocols—Show IEEE 802.2, 802.3, 802.5.  Also clearly show the Physical, MAC and LLC layers on the diagram. Also discuss why IEEE divided the Data Link layer into sublayers.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(b)   Describer how the 4B/5B code works and compare Manchester code and 4B/5B code in term of synchronization capability and efficiency.

 

 

 

 

 

 

 

 

 

 

 

 

(c)    State main reasons why Ethernet is dominating over other LAN technologies.