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Data Comm & Local Area Networks (TCOM 501)

Wide Are Networks & Internet (TCOM 502)

George Mason University

School of Information Technology & Engineering

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Agenda

1. INTRODUCTION2. E-MAIL ADDRESSES3. SYLLABUS REVIEW

A. GRADING STANDARDSB. RESEARCH PAPER REQUIREMENTSC. ADVOCACY PRESENTATIONSD. SUPPLEMENTAL READING

4. HOMEWORK ASSIGNMENTS5. QUIZES6. THE BOOK’S RELATIONSHIP TO THE COURSE

A. FORMULAS7. CHAPTERS 1 & 2

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Homework

1-1 through 1-52-2, 2-7, 2-123-10 through 3-15

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Research Paper Substitute

IBM has a processor that operates at 200 GHz. What is the fastest fiber optic transmission speed that will support? What is the impact if the RAM access speed for a cycle is 60 nanoseconds, the hard drive access speed is 10 milliseconds and the bus speed is 133 MHz? Which of these is easiest to change?

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Optional Case Study

The following case study may be done in lieu of a research paper. It should be performed by two to four students working as a team. Two reports (one for 501 & one for 502) should be approximately 20 pages long and show graphical illustrations of the test performed and results found. An oral presentation should be given as a team.

Take three computers (e.g. 486, 586 and Pentium II) and link each to a server. Place at least three applications on each platform (e.g. e-mail, access database and a graphics application). Develop a test methodology and determine:

1. What is the weak link (slowest component in each platform and the slowest component overall)?

2. What is the response time (user-to-user) of the fastest and slowest application?

3. What is the recommended bechmarking tool to perform the analysis?

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Figure 1-1

Data Communication System Components

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Figure 1-2

Network Criteria

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Figure 1-3

Categories of Standards

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Standards

• Agreed Principles– De Jure– EIA (RS232)– ANSI (X.25)– ITU-T (CCITT) - (X & V Series

“Recommendations”)

• De Facto– IBM, Bell System, et.al.

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Protocol

• A set of Rules Used to Enable Data Communications

• Procedures for Adding Order to the Exchange of Data

• Rules Relating to the Timing and Format of Data Transmissions

• Standard Procedures that Devices Must Accept and Use

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Interfaces & Services

ICI SDU

IDU

SAP

ICI SDU

Layer N+1

Interface

Layer N

SDU

Header

N-PDU

Interface Data UnitInterface Control InfoService Data UnitService Access PointProtocol Data Unit

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Services

Service ExampleReliable message stream Sequence of pages

Reliable byte stream Remote login

Unreliable connection Digitized voice

Unreliable datagram Electronic junk mail

Acknowledged datagram Registered mail

Request-reply Database query

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Service Primitives

Primitive MeaningRequest An entity wants the service to do some work

Indication An entity is to be informed about an event

Response An entity wants to respond to an event

Confirm The response to an earlier request has come back

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Layers In The OSI Stack

ApplicationPresentationSessionTransportNetworkData LinkPhysical

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The Market Dropped!Sell!

7654321

7654321

7654321

7654321

7654321

7654321

APrSTNDLPh

Process 1Computer 1

P(1)OS-SQ P(2,3,4,5)

Add $, CompressP(1)OS-SQ P(n)

C(1)P(1)OS-SQ C(n)P(n)

C(1)P(1)OS C(n)P(n)

C(1)P(1)SQ C(n)P(n)

HHC(1)P(1)OS C(n)P(n)

HHC(1)P(1)SQ C(n)P(n)

GW

321

Router

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Bridge

P2 on C2P3 on C3 P4 on C4

P5 on C5

1

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TCP/IP and the OSI Model

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Do It Yourself

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WHO

• Naming - Addresses– Size

– Format

– Aliases

– Interconnection

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Addressing

Curly Larry

Mo Jim

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HOW

• Connections– Type– Linkage– Bandwidth

• More Names

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Connectivity

Curly Larry

Mo Jim

A

B C

D

E

F

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WHEN

• Timing & Synchronization

• Channel Availability

• Device Availability

• Batch vs. Real Time

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Timing & Spacing

X

Curly Larry

Mo Jim

A

B C

D

E

F

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WHAT

• Payload– Character– Block– Packet/Frame– Assemble/Disassembly

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Packets

TO FROM data…...# of #

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HOW

• Routing

• Quality Assurance– Data Integrity– Error Handling

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Routing

Curly Larry

Mo Jim

A

B C

D

E

F

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Decibells & Logarithms

Converting watts to dB (or milliwatts to dBm): 10 log10 1000 watts = 30 dBw

Converting dB to watts (or dBm to milliwatts):30 dBw = log-1, or log-1 (3) or 10 raised

to the 3rd power = 103 = 1000 watts

35 dBw = 103.5 = 3162.3 watts

Note: There’s a point between the 3 & 5.

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Decibells & Logarithms

dBW Watts -3 .5 0 1 3 2 6 4 9 8 10 10 20 100 30 1000 40 10000

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Nyquist

1. Nyquist: The maximum practical data rate (samples) per channel.

Max R = 2 H log2 V

Logarithmic function to the base 2: For each # V, log V = the exponent to which 2 must be raised to produce V. Then if V = 16, the log2 of V = 4. If V = 2, the log2 of V = 1.

Then what is the maximum practical data rate for BPSK signal on a line with a bandwidth of 3000 Hz?

What is the maximum practical data rate for a QPSK signal on a line with a bandwidth of 3000 Hz?

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Shannon

Shannon: The maximum theoretical data rate per channel.

Max R = CBW x log2 (1 + S/N)

[CBW = H in Nyquist Theorem]

Then what is the maximum practical data rate for signal with a 30 dB S/N on a line with a bandwidth of 3000 Hz?