Client/Server Questions
1. Select either Client/Server or Peer to Peer type of network for the
following situations:
a) Computer Science Department of U of C
b) Small law office consisting of 2 lawyers,
one secretary and two clerks. Each person
has a computer
Justify your selection
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2. Specify which type of server is providing following service:
a) Word processing with MS Word
b) Registration accessing student records
c) Surfing the net
d) Sending e-mail
Types of servers are: File, Print, Application, Message,
Database, Web
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3. Specify which OSI layer is responsible for the following:
1. Deliver the message to the correct node
2. Deliver the message to the correct application
(End to End delivery)
3. Generate/Read electrical pulses
4. Format electrical pulses into frames
5. Communicate with the user
6. Transfer files from source to destination
OSI Layers: Physical, Data link, Network, Transport
Session, Presentation, Application
Protocols
Specify if Connection-oriented or Connectionless
protocol should be used in:
a. Transmitting files between nodes
b. Workstation announcing its presence to the nodes on the subnet
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4. Given the following equations:
Max data rate = 2*frequency*(log(2)no_of_levels)
wavelength = speed/frequency; speed = 300,000 km/sec
delta f = (speed*delta wl)/(wl*wl)
delta f is frequency band
delta wl is wave length band
wl is wave length
Answer the following:
1. What is the maximum data rate of a voice channel
(4000 Hz) using simple modulation?
2. Presume that a voice channel is sampled two times per cycle. Each sample generates one byte of data. What is the equivament bits/sec rate?
3. What is the wave length of the power distribution
lines? (AC current frequency is 60 Hz)
4. Fiber optics cable carries the light of wavelength
1.3 micron (1.3*10(-6) m) and the band is 0.17 micron
a)What is the maximum data rate of 1.3 micron carrirer using a simple modulation?
b)What is the corresponding frequency band of the 0.17 micron wave length band?
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5. High Definition TV (HDTV) screen has 1080 lines, each line having 1920 pixels.
Each pixel has 8 bits. The broadcast speed is 16 screens/sec. Calculate the following:
1. Required bits/sec rate
2. Corresponding carrier frequency using a simple
modulation.
3. How many levels of modulation (in power of 2) would have the normal voice channel modem to be able to distinguish in order to receive HDTV? Presume the carrier signal to be 3600 Hz.
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6. Assume that:
a. Analog channel is sampled every 100 microseconds and each sample consists of one byte of data.
b. An experimental network using fiber optics operates at 10 Gbits/sec. Answer the following:
1. Assuming TDM, how many analog channels can the network carry?
2. How many cycles of a visible light is in one bit of the 10 Gbits/sec network? The frequency of visible light is about 10**15 Hz
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7. Spacecraft is supposed to take pictures or a planet Mars. The quality of the pictures should be the best possible. Answer the following:
1. The link connecting the spacecraft with the earth station is:[Analog/Digital]
2. The portion of the spectrum to be used: [Fiber opt./Microwave/Radio]
3. The transmission from the spacecraft should be:[Analog/Digital]
4. Modulation of the carrier signal [is / is not] required
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7a. Network layer message consists of 10 frames, each frame is 1500 bytes. The error rate of the transmission line is 1 bad bit in 10**6 good bits. Overhead for one frame ACKnoledged is 10 bytes.
Should the Data Link layer use Acknowledged or Non - acknowledged service?
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8. Protocol can provide the following services:
a) Connectionless, unacknowledged
b) Connectionless, acknowledged
c) Connection-oriented
Answer the following:
1. A node wants to broadcast a message to many nodes simultaneously. Which service is the most suitable and why?
2. Sliding window protocol with window size 1 implements ...... service
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8a. Line Utilization.
Consider the following: 1 Gbit/sec satellite channel, distance between source and destination 100,000Km. Sliding window protocol, window size 16. Frame size is 1500 bytes. Speed of light is 300,000 Km/sec.
a) What is the line utilization?
Solution:
Duration of data burst = (16 * 1500 * 8) / 10**9
= 2 * 10**(-4) [sec]
Round trip time = (2 * 100,000) / 300,000 = 0.67 [sec]
Line utilization = Data burst time / Total time
= (2 * 10**(-4)) / 0.67 = 0.03%
b) What is the window size in order to utilize the line 100% ?
(1500 * 8) / 10**9 * X = 0.67 -> X = 50,000 frames
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9. Considering the CSMA/CD MAC protocol answer the following:
1. With the length of the cable(s) increasing the probability of the collision is [increasing/decreasing]
2. With respect to the collisions it is better to send [few long messages/many short messages]
3. With increase of the transmission speed the probability of the collision is [increasing/decreasing]
4. Fiber optics implementation of CSMA/CD will have [grater/smaller] probability of the collision.
5. Two nodes are communicating using CSMA/CD protocol. Speed of transmission is 100 Mbits/sec and frame size is 1500 bytes. Calculate the distance between the nodes such that the time to transmit the frame = time to recognize that the collision have occurred.
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10. Consider the following network:
______
| |
| HUB 2 |
| ____ |
|_________|
________ _________
| | | |
| HUB 0 | | HUB 1 |
| ____ | | _____ |
|________ | |________ |
4 NODES 4 NODES
For the 4 situations below answer the following:
a) What is the broadcast domain ?
b) What is the collision domain?
c) What is the bandwidth available to each node?
1. All hubs are 10 BASE T ETHERNET (CSMA/CD) hubs
2. All hubs are 10 Mbits/sec switched ETHERNET hubs
3. Hub 2 is 100 Mbits/sec switched ETHERNET hub
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11. Consider the following IP address 136.159.7.2; Netmask: 255.255.252.0
1. What class of address is it?
2. How many subnets are available?
3. How many hosts on each subnet?
4. What is the subnet number?
5. What is the host number?
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Classless InterDomain Routing - CIDR
CIDR Block Prefix # Equivalent Class C # of Host Addresses
/27 1/8th of a Class C 32 hosts
/26 1/4th of a Class C 64 hosts
/25 1/2 of a Class C 128 hosts
/24 1 Class C 256 hosts
/23 2 Class C 512 hosts
/22 4 Class C 1,024 hosts
/21 8 Class C 2,048 hosts
/20 16 Class C 4,096 hosts
. . .
. . .
. . .
/13 2,048 Class C 524,288 hosts
Example: Consider the following:
Site ID: 194.24.16.0 11000010 00011000 00010000 00000000
CIDR mask: /20 11111111 11111111 11110000 00000000
Netmask: 255.255.255.192 11111111 11111111 11111111 11000000
The highest IP 194.24.31.255 11000010 00011000 00011111 11111111
# of subnets: 2**6 -2
# of hosts: 2**6 - 2
12. Consider the following CIDR IP address: 194.24.16.0 / 20
a) What is the lowest IP address?
b) What is the highest address?
c) How many nodes for this site?