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|Problem |Weight |Grade |

|1 |25 | |

|2 |20 | |

|3 |15 | |

|4 |20 | |

|5 |20 | |

| | | |

| | | |

| | | |

|Total |100 | |

Jordan University of Science and Technology

Department of Network Engineering and Security

NES 311: Data Communication

First Exam – Nov. 2, Fall 2014

Student’s Name:________________________ Student’s ID:----------------

|Instructions: |

|Turn off your cell phone, don’t even use it as a calculator |

|Use your own calculator only and don’t pass things around |

|Communicate with the professor only |

|Time allowed is 60 minutes |

|Copy your answer for Problem 1 to the table below. |

Problem 1 (Fill in the following table with the CAPITAL letter symbol of the answer)

|Q# |1 |2 |

|1 | |T |

|2 | |T |

|3 | |T |

|4 | |F |

|5 | |F |

|6 | |F |

|7 | |T |

|8 | |T |

|9 | |F |

|10 | |F |

|11 | |F |

|12 | |F |

|13 | |T |

|14 | |T |

|15 | |F |

Problem 3: (20 Points, equal weight )

a. Determine the signal power at PC1.

Solution 1:

⇨ Total db=loss in four (Ethernet) links + loss in the serial link between Router 0 & Router 1+ gain in four intermediate devices

⇨

⇨ Total dB=4(-0.75)+(10x-0.75)+4(+3)=1.5

⇨ 10 log(PC1/PC0)=1.5

⇨ Log (PC1/PC0)=10^0.15

⇨ PC0= PC1*1.412

⇨ PC0=5*1.412=7.06 Watts

Solution2: (or student may choose to calculate power at each interface)

b. Calculate the total loss in dB over the links from PC0 to PC2?

Total db=loss in four (Ethernet) links + loss in the seriallink between Router 0 & Router 1+ gain in four intermediate devices

Total dB=4(-0.75)+(10x-0.75)+4(+3)=1.5

Or : dB=101og (PC1/PC0)

dB=10 log (7.06/5)= 1.5 dB

c. Determine the signal power at the output interface of Router1 in dBm

Solutions 1:

dB between Router 1 & PC1= -0.75+(=3)+-0.75=1.5 dB

1.5=10log(PC1/PR1)

(0.15=log(7.06/PR1)

( PR1=PC1/10^(0.15)= 7.06/1.412=5.018 Watts

d. If average noise power of the link between end-to-end devices is 0.5 dBm, Express the noise power in Watts.

Solution:

dBm=10log (Pm)

⇨ 0.5=10log (Pm)

⇨ Pm=10^(0.05)=1.122 mW

⇨ P (in Watts)=1.122mWx10^-3 Watts

Problem4: (25 Points, equal weight )

Consider a message traversing through the network links from PC1 to PC2 in Figure 1. The MAC and IP addresses for the devices are given in the table shown below.

a. Show the content (H2 and H3) of the frame when it is just sent by PC1.

| 0F-11-11-00-00-01 | C1-00-00-C1-AA-BB | 172.0.6.2 | 10.0.5.2 | |

| | | | |Data |

b. When the packet is traveling on the serial link between Router 1 and Router 2, what is the content of Header 3.

| BB-BB-BB-BBB-FF-B1 | AA-AA-AA-AA-AA-A1 | 172.0.6.2 | 10.0.5.2 | |

| | | | |Data |

c. Show the content (H2 and H3) of the frame when it is just received by PC2.

| C1-00-00-C1-AA-EE | 0D-DD-DD-DD-DD-D1 | 172.0.6.2 | 10.0.5.2 | |

| | | | |Data |

d. If you are to add Header 4, show the content (H2+H3+H4) of the frame when it is passing the link between Switch1 and Router 1 (use any valid address for H4).

|AA-AA-AA-AA-AA-A0 | | 172.0.6.2 | 10.0.5.2 |Any int. number |Any int. number | |

| | | | |(0-65,535) (e.g.|(0-65,535) (e.g.|Data |

| |0F-11-11-00-00-02 | | |80) |80) | |

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