1 data comm & local area networks (tcom 501) wide are networks & internet (tcom 502) george...
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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
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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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34
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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?
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