Review for Exam 3 School of Business Eastern Illinois University © Abdou Illia, Spring 2006

Review for Exam 3

School of BusinessEastern Illinois University

© Abdou Illia, Spring 2006

Local Area Networks


3Servers

Single server Versus Multiple specialized Servers– Decision based on Cost, Optimization, Reliability, and Security

Optimization: – File servers need storage capacity and rapid access– Client/Server applications need very fast processors

4Servers

Print Server: basically NIC + a parallel port + Random Access Memory + Intelligence to receive data and commands from print queue manager program.

Note: Possible to connect printer directly to file server, but people might have to walk far to get their printout.

Newer printers have built-in NICs

& print server hardware

5Servers

File Server: A server that acts like a very large hard disk shared by many client PCs

Advantages: Single program installation, Sharing programs and files with access rights.

Operates according to the File

Server Program Access System

seen during Classes 2&3

6File Server Program Access

For execution,– Program and data files are downloaded (copied) to the

Client PC– Processing on the client PC, not on the file server– File server merely stores programs and data files

File ServerClient PC

Downloaded toClient PC,Executed There

7

Summary Questions

What are the four factors to take into account in deciding how many servers to use to implement a LAN’s services?

Answer: Optimization, reliability, security, cost To what two devices does a print server connect?

Answer: To a printer via a parallel or USB cable and to a hub or switch via UTP

In print service, where does a print job go when it leaves the client PC (not counting the hub or switch)?

Answer: The print job first goes to the computer where the Print Queue Manager program is installed.

Do you have to use special printers for print service?

Answer: You do not need special printers, because any printer fed by a parallel or USB cable could be connected and shared to provide print service.

8

Summary Questions

Can anyone access shared files?

Answer: No. Only those who have access rights.

Why does file sharing for programs make software installation easier?

Answer: A program only has to be installed once, on the file server, not on each client PC.

Why is storing program files on a file server limiting?

Answer: Programs stored on file servers execute on client PCs, which have limited processing power.

9Software and Support Systems

- Workstation Operating System

- Network Operating System- Application programs:

- Word processor- Spreadsheets- Accountability

- Utility programs

• Workstation Operating System on Client PCs• Network Operating System on Servers

10Ethernet standards

Q: If a LAN is described as 10BaseT, list everything you know about that network?

11Summary Questions

Your organization has 12 employees, each with his or her own stand-alone PC running Windows 98. a) List all the additional hardware and software you would have to buy to install a simple PC network. Be very sure that you list all the things the organization will have to buy. The organization wishes to use electronic mail, word processing, file sharing, and print sharing with four existing printers. b) How many ports on the hub or switch will your organization use? Explain.

c) Suppose that a decision have been made to implement the 100BaseTX Ethernet standard. What does it mean in terms of the characteristics of the following components: Hub/Switch, NICs, Wiring.

Answers are in Week8SummaryQuestions.doc (Review section of course Website)

12Automatic Inheritance of Access Rights

Assigning rights to users or group in a directory Rights automatically inherited in lower directories Simplifies rights assignment

Application

Word Processing Database

Oracle QuickDB

Assigned BrowseAnd Read Rights

Inherits BrowseAnd Read Rights

Inherits BrowseAnd Read Rights

13Automatic Inheritance of Access Rights

Blocking of Inheritance– If rights explicitly assigned in subdirectory, inheritance is blocked– Only assigned rights are effective

Application

Word Processing Database

(Browse and Execute Only)QuickDB

Assigned BrowseAnd Read Rights

Inherit BrowseAnd Read Rights

Assigned BrowseAnd Execute Rights Oracle

14Summary Questions

1. (a) What is LAN management ? (b) Name some common management activities.

2. a) What are access rights? b) How does the use of groups simplify the assignment of access rights? c) How does automatic inheritance simplify the assignment of access rights? d) How does explicit assignment modify automatic inheritance?

Answers are in LAN-Management.doc (Review section of course web site)

15Summary Questions

3. Directory Applications has Subdirectories Databases and WordProcessings. The Network administrator assigns user Lee to the group Outer. The administrator assigns Outer the access rights R, S, and T in Directory Applications. (Don’t worry about the meaning of R, S, and T. They are simply types of rights.) The administrator assigns Outer the access rights S, U, and V in Subdirectory Databases. a) What access rights does user Lee have in Directory Applications? Explain. b) What access rights does user Lee have in Directory Databases? Explain. c) What access rights does user Lee have in Directory WordProcessings? Explain.

Applications

WordProcessingsDatabases

Answers are in LAN-Management.doc (Review section of course web site)

16

Reviewing Quiz 1 could also be helpful

Wide Area Networks


18Wide Area Networks basics

A station is a device that interfaces a user to a network

A station can be:– a computer (for Data networks)– a telephone (For Voice networks)


Data is transferred from node to node through the network

A Node is a transfer point for passing data through the network

A Node is often a computer, a router, or a telephone switch

Q: What is the difference between a station and a node?


The subnet is the underlying physical connection of nodes and communication lines that transfer data from one location to another.

A Subnet is a collection of nodes and different types of transmission media

Q: How does the subnet differ from the network?

21Circuit Switching Subnet

Usually used for Voice networks

A subnet in which a dedicated circuit is established between sender and receiver and all data passes over this circuit.

22Virtual-Circuit Packet Switching Subnets Amount of data broken into n packets

A virtual circuit (temporary path through the network) is determined

Note: The virtual circuit is not dedicated (not reserved)

All n packets transmitted through the virtual circuit

When transfer completed, virtual circuit dissolved

Q:

23

Summary Questions

How does the subnet differ from the network?

Answer: The network include: the subnet(s), the stations, the OS & other application software, and the other networking devices & transmission medium needed to connect the stations to the subnet

What is the difference between a station and a node?

Answer: A station is the device that interfaces a user to the network. A node is transfer point for passing data through the network. A node can be a computer, a router, or a telephone switch.

What are the main characteristics of Circuit Switched networks?

Answer: In Circuit Switched networks: (1) a dedicated circuit is established between sender and receiver, (2) circuit capacity is reserved during the duration of each communication, at each node (switch) and on each transmission line; (3) no routing decisions are necessary since circuit is dedicated.

24

Summary Questions

What are the main characteristics of Virtual-Circuit Packet Switched network?

Answer: (1) Data sent in packets, (2) all packets follow the same virtual circuit, (3) the virtual circuit may be shared with packets from other conversions, (4) no routing decisions except the first ones that create the circuit.

Name some criteria that routing decisions are based on

Answer: see slide #17 in appropriate class notes Name two routing algorithms/techniques.

Answer: see slide #18-19 in appropriate class notes

25

Reviewing Question #2 of Review Exercise (WAN) available in the Notes’ section of the course web site could be helpful.

Telecommunications Systems


27

Review:- Class notes titled “Telecommunications Systems, Part 1”

(Slides 1-13)

- Class notes titled “Telecommunication Systems, Part 2” (Slides 1-13)

28

Summary Questions1. When a standard telephone line is used to connect to a network: (a)

What device limits the speed? (b) Where is this device located?

(a) The analog-to-digital converter (ADC).

(b) It is located at the telephone company’s switch at the end of your local loop access line.

2. (a) In using a V.90 modem, what does the ISP need? (b) What does the telephone company need?

(a) A digital leased line to the telephone carrier (and some internal equipment).

Note: The ISP does not have a V.90 modem. If it did, it could only transmit at 33.6 kbps, and the receiver could only receive at 33.6 kbps.

(b) The telephone company does not have to do anything differently.

Note: the telephone company does not have to install ADCs. These are already there. You use ADCs and DACs every time you make a voice telephone call.

29

Summary Questions

3. (a) How are 56K Leased lines and standard telephone lines different in terms of operation? (b) How are they different in terms of speed and cost?

(a) With Standard telephone lines you need to dial a telephone number to connect. The connection is no permanent (active only during a call). With 56K Leased line, there is no need to dial a telephone number, and the connection is always active.

(b) 56K Leased lines are faster and more expensive.

30

Summary Questions

1. What is the difference between a T-1 Trunk line and T-1 Leased line?

Answer: A T-1 trunk line only runs between two switches within the telephone network. T-1 Leased lines extend T-1 trunk line speeds to end-to-end circuits between 2 locations.

2. In T-1 Leased lines, what kind of twisted pair wire is used to connect a customer to the 1st telephone switch?

Answer: Data-grade TP which is a category 2 TP.

31

Summary Questions

3) On the user end, what elements are needed to establish a DSL connection?

A computer, a DSL modem, splitter(s) to separate regular telephone line from the DSL data line, tel. line, and ISP, software programs (OS, client application programs, TCP/IP)

4) Several Internet access systems are asymmetric, with higher downstream speeds than upstream speeds. (a) Is this good for Webservice? (b) Is it good for videoconferencing?

a) Asymmetric speeds are good for Webservice because requests tend to be small but downloaded pages large.

(b) It is not good for videoconferencing, which needs high speed in both directions.

32

Reviewing Quiz 2 could also be helpful

33Standard telephone line

ADC limits transmission speed

ADC needed because internal telephone system is digital

The Internet


35

Review class notes titled “The Internet”, (Slides #1-17)

36Summary Questions

1. a) Distinguish between IP address and host name. b) Which is the official address of a host? c) Does a server host need an IP address? d) Does your home PC need an IP address when you are on the Internet? e) Does a server host need a host name? f) Does your home PC need a host name when you are on the Internet?

2. Using the conversion system in slide #10, convert the following IP address to dotted decimal notation: 10101010 11110000 11001100 01010101. (Spaces are included to facilitate reading.)

37

Summary Questions

3. a) What are the two parts in IP addresses? b) What part do border routers look at to determine whether the destination host is within the network or outside the network?

4. a) Who assigns the Network part? b) The Local part?

5. Check questions on slide #17 in class notes

Documents

Review for Exam 3 School of Business Eastern Illinois University © Abdou Illia, Spring 2006