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Networking Test Page

assignment in the syllabus (Monday around midnight.) No credit will be given for late turn-ins.

 

Part 1

 

Answer the following: (3 points):

Open the link for “1”, which is chapter 1, to the right of “Select Chapter”

What links are available on the left side, besides: PowerPoint’s, and Text Book Images?

Open up “animations”, and view “Packet Traveling Through Layers”

In one or two sentences, indicate your impression of the animation?

It’s an animation that shows one computer sending data to another computer on a network. It also shows the set layers that the data must travel thru. On the first computer you see the data traveling downward thru the layers then out to the physical network and then 2nd computer reverses the process unpacking it.

 

Part 2

Write out the question number, the question itself (this will greatly help you when you review for a test), and then your answer.

 

(A) Chapter 1, page 15, complete questions 3, 4, 5, 8, 11, and 12

1.3 According to the text it is possible to develop Internet apps w/o understanding the architecture of the Internet and technologies as long as the “programmer masters the interface; no further knowledge of networking is needed”. However, “a programmer who understands the underlying network mechanisms and technologies can write network apps that are more reliable, correct and efficient.”

 

1.4 data communications refers to the study of low-level mechanisms and

technologies used to send information across a physical communication medium, such

as a wire, radio wave, or light beam.

1.5 Packet switching is a communications paradigm that divides data into small blocks, called packets, and includes an identification of the intended recipient in each packet.

1.8 A communication protocol specifies the details for one aspect of computer communication, including actions to be taken when errors or unexpected situations arise. A given protocol can specify low-level details, such as the voltage and signals to be used, or high-level items, such as the format of messages that application programs exchange.

1.11 List the layers in the TCP/IP model, and give a brief explanation of each.

Layer 1: Physical

Physical layer specifies details about the underlying transmission

medium and the associated hardware.

• Specifies

o electrical properties

o radio frequencies, and signals

Layer 2: Network Interface

This layer specifies details about communication

Between higher layers of protocols

• Specifies

o network addresses

o maximum packet size that a network can support

o protocols used to access the underlying medium, and hardware addressing belong in layer 2

 

Layer 3: Internet

Layer 3 is the fundamental basis layer for the Internet it specifies communication between two computers across the Internet

• Specifies

o The Internet addressing structure

o format of Internet packets

o method for dividing a large Internet packet into smaller packets for

o mechanisms for reporting errors belong in layer 3.

Layer 4: Transport

Protocols in the Transport layer provide for communication from an application

program on one computer to an application program on another.

• Specifies

o maximum rate a receiver can accept data

o mechanisms to avoid network congestion

o techniques to insure that all data is received in the correct order

Layer 5: Application

Is the top layer of the TCP/IP stack specify how a pair of applications

interact when they communicate.

• Specifies

o details about the format and meaning of messages that applications can exchange as well as procedures to be followed during communication.

§ Examples

• email exchange

• file transfer

• web browsing

• telephone services

• and video teleconferencing

1.12

A header is additional information that is added by a protocol. In each layer each layer of protocol software performs computations that insure the messages arrive as expected. The sending computer prepends this extra information (header) onto the packet; the corresponding protocol layer on the receiving computer removes and uses the extra information.

 

Additional questions:

Public networks have public IP address meaning that anyone can connect to the network by paying a subscription fee (internet service providers). A private network is controlled by a particular group. Private networks have private IP addresses and are not accessible to those outside the network.

 

What does it mean when two entities interoperate?

Interoperation is when two entities can communicate without any misunderstanding.

Chapter 2

2.6 The transition in graphics started in the 1990’s with the transfer of images, then by the late 1990’s video clips, and even full motion videos became conceivable, and today we have the ability to watch HD movies and shows and even 3D steaming in the near future.

2.7 It started with alert sounds and shifted to human voice then audio clips became available. By the late 1990’s video clips were able to be transmitted and downloaded and high quality multimedia content as well as high-fidelity audio became typical.

2.9 Analog systems have switched to digital and are now implementing the use of V.O.IP

2.10 Because with wireless technology we now have the ability to get low latency, high speed internet, in places where a hard line in not feasible, or cost efficient. I have benefited

from this technology personally because I live in a rural area and before a descent WISP moved in we used satellite and it was horrible.

Access into and explore the following web site. It contains information related to the growth of the Internet. Open the World Stats tab and view the information. Open the America Stats tab and view the information. In both cases you can view charts (scroll down first).

http://www.internetworldstats.com/emarketing.htm

 

 

As a percent, which world region has the most users? (Look at the charts) (1 point)

North America

Scroll down and locate and open the Web Browser Statistics link. What two browsers are most widely used? 1 point

Firefox and Internet Explorer

Scroll farther down - Under Internet Usage Reports: What are the top 3 languages used on the Internet? (1 point)

English, Chinese, and Spanish

Either do Part 1 (a), or part 1 (b).

(a). The client is calling the server and then the server accepts. And now they are ready to send and receive info between each other

Part 2

(A) Chapter 3

3.1 What are the two basic communication paradigms used in the Internet?

Stream & Message paradigms

3.3 Give six characteristics of Internet message communication.

Connectionless

Many-to-many communications

Sequence of individual messages

Messeges restricted to 64k

Used for multimedia apps

Built on UDP protocol

3.5 If a sender wants to have copies of each data block being sent to three recipients, which

Paradigm should the sender choose?

Message because it can handle 1 to many

3.6 What are the three surprising aspects of the Internet’s message delivery semantics?

Messages can be lost, duplicated or received out of order.

3.7 Give the general algorithm that a connection-oriented system uses.

Purpose:

Interaction over a connection-oriented mechanism

Method:

A pair of applications requests a connection

The pair uses the connection to exchange data

3) The pair requests that the connection be terminated

3.8 When two applications communicate over the Internet, which one is the server?

The server is the application that starts first, doesn’t need to know which client will contact it, waits for a client to contact it, communicates by sending and receiving data, and stays running after client terminates.

3.11 Can data flow from a client to a server? Explain.

Yes although it typically goes from the client sending a request and the server returning a response other relations are possible.

3.14 What two identifiers are used to specify a particular server?

The IP address for the computer and the protocol port number that the service is on.

3.24 Why is symbolic constant INADDR_ANY used?

It allows the server to operate on a multi-home host by allowing a server to specify port number while allowing contact at any of the computer’s IPs

 

 

(B) Chapter 4, pages 80 – 81

4.1 What details does an application protocol specify?

The syntax and semantics of messages that can be exchanged

Whether the client or server in it initiates interaction

Actions to be taken if an error arises

How the two sides know when to terminate communication

4.3 What are the two key aspects of application protocols, and what does each include?

Representation and transfer

Data Representation:

Syntax of data items that are exchanged

Specific form used during transfer

Translation of integers, and characters, and files between computers

Data Transfer:

Interaction between client and server

Message syntax and semantics

Valid and invalid exchange error handling

Termination of interaction

4.6 What are the four parts of a URL, and what punctuation is used to separate the parts?

Protocol followed by a “://” then computer_name followed by “/” then document_name followed by “%” parameters

4.9 What does a browser cache, and why is caching used?

Images such as (GIF’s) & (JPEG’s) and its used to load frequently visited webpage’s faster by storing the images.

4.12 When a user requests an FTP directory listing, how many TCP connections are formed?

Explain.

Ftp uses 2 TCP connections one for control commands (control connection) and one for actual data (data connection)

4.16 List the three types of protocols used with email, and describe each.

SMTP: Is the standard protocol that a mail program uses to send mail over the internet

4.20 What are the two main email access protocols?

POP3,IMAP

4.22 What is the overall purpose of the Domain Name System?

Maps readable names to computer addresses

4.24 True or false: a web server must have a domain name that begins with www. Explain.

False, because www is merely a convention for humans.

4.25 True or false: a multi-national company can choose to divide its domain name hierarchy in such a way that the company has a domain name server in Europe, one in Asia, and one in North America.

True

 

Extra questions:

Access into the following Web site. http://www.economist.com/node/17627815

It discuses some of the roles of ICANN: the Internet Corporation for Assigned Names and Numbers.

There are a few typos in the text, but other than that it’s somewhat informative.

What does ICANN oversee? (1 point)

Top level domain registries.

2. What do governments want a say over, and why?

Over what internet addresses can be used.


Assignment 3

Due January 31, 2011

25 points

 

Part 1

Please watch chapter 6’s animation. There are no points related to the animation this week.

 

Part 2

Write out the question number, the question itself, and then your answer.

(A) Chapter 5, page 91, complete questions 3, 4, 5
+ 1 extra question

5.3 What are the conceptual pieces of a data communications system?

Information Source, Source Encoder, Encryptor (Scrambler), Channel Encoder, Multiplexor, Demodulator, Demultiplexor, Channel Decoder, Decryptor (Unscrambler), Source Decoder, Destination

 

5.4 Which piece of a data communications system handles analog input?

Information Sources

 

5.5 Which piece of a data communications system prevents transmission errors from corrupting data?

Channel Encoder and Decoder

Extra question:

According to the textbook, what is the purpose of a multiplexor? (1 point)

Answer: It is the way multiple forms of information are combined across a shared medium.

Side note “I know that I used to work with multiplexors in the cable industry and we could combine/split multiple sources of signal over one line” is it a similar concept in a networking situation?

(B) Chapter 6, pages 110 – 111

6.3 Why are sine waves fundamental to data communications?

Sine waves are crucial in the matter of input processing because there are many natural phenomena that produce signals that correspond sine waves as a function of time.

6.4 State and describe the four fundamental characteristics of a sine wave.

Frequency:

the number of oscillations per unit time (usually seconds)

Amplitude:

the difference between the maximum and minimum signal heights

Phase:

how far the start of the sine wave is shifted from a reference time

Wavelength:

the length of a cycle as a signal propagates across a medium

6.9 What is the analog bandwidth of a signal?

Analog bandwidth is the difference between the highest and lowest frequency of its components.

 

6.12 What is the definition of baud?

Baud is the number of times a signal can change per second.

6.15 What is a synchronization error?

It’s a mismatch in interpretation between sender and receiver which usually takes place due to timing issue in the sender’s or receiver’s hardware. Line coding techniques are one way to combat synchronization errors.

6.17 What aspect of a signal does the Manchester Encoding use to represent a bit?

Transitions, not levels to define bits.

6.20 If the maximum frequency audible to a human ear is 20,000 Hz, at what rate must the analog signal from a microphone be sampled when converting it to digital?

40,000 Hz

6.22 Describe the difference between lossy and lossless compressions, and tell when each might be used.

Lossy

Some information is lost during compression

Typical in audio and video compression such as .avi

Higher compression is achievable

Lossless

all information is retained in the compressed version.

Preserves original data w/o change

Not as high of compression as lossy

Extra questions

How are high frequencies and megahertz related?

Megahertz are the measurement/rating of a high frequancy

What is the bandwidth of an analog signal frequency height of 4 Khz, and a frequency low of 1 Khz. (1 point)

3Khz

What is “period” known as?

Frequency calculated as the inverse of time for one cycle.

Examine figure 6-3. (a) and (b) both have sin formulas. In reference to “cycles” or “period”, why are the charts different? (2 points)

The frequency is higher in (b) then (a) and you can see this as the number of cycles are more numerous in (b)

 

There are some web sites containing either text or videos which may help you understand some concepts.

 

I would like your opinion on either one of the following two web sites. Were you able to learn some things? Name 4 things you learned. (2 point of extra credit)

I learned about transverse waves and how they travel horizontally

I learned that after a wave is reflected it changes its position when traveling to it points upward then coming back it points downward

I learned that if wave is reflected in some cases it can cause overlay which causes interference.

I learned that when a wavelength is bigger than an obstacle, sound waves can bend around the obstacle.

 

Assignment 4

 

Part 1 (2 points)

“Row and Column Parity Checking”, is checking each binary number/data bit for an even or odd number. It does this in both the rows and the columns so that information can be encoded along with the data so that the receiving computer will know whether the information is the correct or not. For example if the number of one’s is odd then another 1 is need to become even therefore the encoded bit is recorded as 1 even parity bit.

Part 2


7.3 What happens when noise encounters a metal object?

Electromagnetic radiation is produced creating a small signal which can cause interference.

7.4 What three types of wiring are used to reduce interference form noise?

Unshielded twisted pair shielded twisted pair, coax cable.

 

7.10 List the three forms of optical fiber, and give the general properties of each.

Multinode step index

Least expensive

Lower performance

Boundary between fiber and the cladding is abrupt causing break what reflection

High dispersion rate

Multinode graded index

More expensive than Multinode step index

Density increases near the edge reducing reflection lowering dispersion

Singlenode

Most expensive

Least this portion

Smaller in diameter and other properties that reduce reflection

Use for long distances and higher bit rates

7.12 What is the chief disadvantage of optical fiber as opposed to copper wiring?

Fiber is very expensive

7.16 What are the two broad categories of wireless communications?

Terrestrial, non-terrestrial

7.20 What is propagation delay?

delay in network because of the amount of time the signal takes to travel across a transition medium

Extra questions

In reference to electrical interference: Why is twisted pair wiring advantageous over two wires which run parallel? (1 point)

Because they absorb some of the radiation from one another in twisted pair which lowers the total amount of radiation emitted from a circuit pair.

In reference to optic fiber, discuss “critical angle”, “refracted”, and “reflected” (2 points)

 

 

 

(B) Chapter 8, pages 149 – 150

 

8.1 List and explain the three main sources of transmission errors

Interference

Electromagnetic radiation emitted from Electronic Devices and cosmic radiation causes noise that can mess up radio transmissions and signals across wires.

Distortion

Signal blocked by outside sources or distorted commonly caused by metal objects altering frequencies.

Attenuation

Degradation of signal that occurs after long distance travel.

8.8 Compute the Hamming distance for the following pairs: (0000, 0001), (0101, 0001),

(1111, 1001), and (0001, 1110).

d(0000, 0001) = 1

d(0101, 0001) = 1

d(1111, 1001) = 2

d(0001, 1110) = 4

8.12 What can a RAC scheme achieve that a single parity bit scheme cannot?

RAC can detect errors in which two or three bits are changed.

8.14 What are the characteristics of a CRC?

Arbitrary Length message

Excellent error detection

Fast hardware implementation

 

 

Extra questions

Finish the table indicating what the Even and Odd parity values are. (2 points)

Original Data Even Parity Odd Parity

01011011 1 0

01101101 1 0

00110011 0 1

 

2.

Generate a RAC parity matrix for a (20, 12) coding of the dataword 1000 1101 1111. I have started it for you: (2 points)

1 0 0 0 1

1 1 0 1 1

1 1 1 1 0

1 0 1 0 0

 

 

 

 

Part 3

On your own, find answers for the following two questions:

What is the importance of angles in a fiber bundle? (1 point).

Because there is a certain point at which light cannot bend; thus, if the angle is too much you can get reflection or dispersion effect.

What is the optical fiber line made of: (1 point)

Glass and plastic

 

2. The manufacturer of optical fiber. Watch the following video, and answer the questions.

http://www.youtube.com/watch?v=EFl1dHUJj98&feature=player_embedded

The name of the video is: “OFS Manufacturing High-Performance Optical Fiber”

 

2.1 This question is from the video. What is driving the growing need for fiber? (within the first minute) (1 point)

Information Technology and access to it, such as telephone, internet, multimedia

 

Give examples of where Multimode fiber is used: (around 1 minute and 22 seconds): (1 point)

What is the first step in the process (1 point)

Creation of a solid glass rod.

 

2.4 What is attenuation? (1 point) around minute 6.5

Degradation of signal that occurs after long distance travel.

 

2.5 Find the answer to this question on your own. It’s not particularly in the video. What is the importance of: “Bendable fibers” (1 point).

Bendable fibers allow for the cable to be bent without damaging the cable or messing up the transmission

Part 4

Please access into (and read through the content of) the following web site, which discusses cable standards: http://en.wikipedia.org/wiki/T568B

Please answer the following questions. Each question is worth ˝ point of extra credit.

What types of organizations were involved in developing the TIA/EIQ 568–B standard?

There were over 60 contributing organizations; manufacturers, end-users, and consultants. 

TIA/EIA-568-B attempts to define standards that will enable what?

structured cabling systems for commercial buildings, and between buildings in campus environments

What is the range of allowable horizontal cable distances for twisted-pair cable types, and for fiber optic?

90m

What type of cable standard would need to be used to support 10GBase-T connections?

Copper twisted pair

What is a purpose of a crossover cable?

interconnect two computers for the purpose of direct communication