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1 Module 1 Introduction to Internetworking By Dr. Percy DIAS © 2009, Cisco Systems, Inc. All rights reserved.
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Page 1: Internetworking fundamentals(networking)

1

Module 1

Introduction to Internetworking

By Dr. Percy DIAS

© 2009, Cisco Systems, Inc. All rights reserved.

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Computing Measurement Terms

• Bits are binary digits. They are either 0s or 1s. In a computer, they are represented by On/Off switches or the presence or absence of electrical charges, light pulses, or radio waves.

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Computing Measurement Terms

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Base 10 (Decimal) Number System

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Base 10 (Decimal) Calculations

• Should be familiar because you’ve used it since childhood• Example: the number 235 = (2 x 100) + (3 x 10) + (5 x 1)• Because you’ve used it so long, you probably don’t think

about it

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Base 2 (Binary) Numbers

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Base 2 (Binary) Numbers

• Binary uses just two digits, 0 and 1• Similar to Base 10; differences are in the details• Example: the binary number 11101011 is equivalent to the

decimal number 235 – Add the decimal value of each bit to get the decimal number

• (1 * 128) + (1 * 64) + (1 * 32) + (0 * 16) + (1 * 8) + (0 * 4) + (1 * 2) + (1 * 1) = 235 decimal

1

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Four-Octet Dotted-decimal Representation of 32-Bit Binary

Numbers• Split the binary number into four groups of eight

binary digits. Then convert each group of eight bits, also known as an octet into its decimal equivalent.

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Converting IP Addresses Between Decimal and Binary

• IP addresses are 32-bit binary numbers• Humans find it easier to read decimal

numbers, so IP addresses are often expressed in dotted-decimal format

• Each decimal number represents 8 binary digits, also know as an “octet”

• Each octet can be converted to a decimal number between 0 and 255, inclusive

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Converting Decimal to Binary

Start by dividing the decimal by the largest number in the Value row that will go.

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Converting 8-bit Binary Numbers to Decimal Numbers

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Converting 8-Bit Binary to Decimal

• Binary numbers are converted to decimal numbers by multiplying the binary digits by the base number of the system, which is base 2, and raised to the exponent of its position.

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Hexadecimal• The base 16, or hexadecimal (hex), number

system is used frequently when working with computers, because it can be used to represent binary numbers in a more readable form.

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Hexadecimal

• Popularly called “hex”

• Each hex digit represents 4 bits

• Uses 16 symbols: 0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F

• A = 10, B = 11, C = 12, D = 13, E = 14, F = 15

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Conversion

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Boolean or Binary Logic• Boolean logic is based on digital circuitry

that accepts one or two incoming voltages. • Boolean logic is a binary logic that allows

two numbers to be compared and generate a choice based on the two numbers.

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Boolean or Binary Logic

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Network Protocols

• Communication must follow a set of rules• Networking rules are defined by a set of

standards and protocols• A single standard or protocol defines what a

small part of the network does• The Transmission Control Protocol/Internet

Protocol (TCP/IP) suite defines a large set of standards and protocols used to network computers

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Media

• Media refers to the various physical environments through which transmission signals pass.

• Common network media include twisted-pair, coaxial, fiber-optic cable, and the atmosphere through which wireless transmission occurs.

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Network Media

Media Example Encoding

Copper Twisted-pair cable usually used as LAN media

Electrical pulses

Fiber-optic Glass or plastic fibers in a vinyl coating usually used for long runs in a LAN as a trunk

Light pulses

Wireless Connects local users through the air

Electromagnetic waves

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Network Media

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Local-area Networks (LANs)

LAN Technology: Ethernet, Token Ring, FDDI (Fiber Distributed Data Interface)

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Wide-area Networks (WANs)

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Internetworks Made Up of LANs and WANs

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Importance of Bandwidth

• Bandwidth is defined as the amount of information that can flow through a network connection in a given period of time

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Bandwidth Pipe Analogy

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Bandwidth Highway Analogy

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The Need for Networking Protocols and Standards

• 1960s to 1980s – Each vendor set its own proprietary protocols and standards

• Equipment from different vendors would not interoperate

• Eventually, open standards were agreed upon

• Open standards allow more competition, which increases speed of development

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Using Layers to Describe Data Communication

• Data communication is a very complex process.• Difficult to understand this process as a whole.• Solution is to break down the total network

communication system into a series of layers.• Each layer is responsible for a specific part of

network communication.• These layers interact with the layer above and

below.• Two common network models that use layers

are Open System Interconnection (OSI) reference model and the TCP/IP reference model.

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OSI Reference Model

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Functions of Layer 7

• Application Layer: Network Process to Applications – Provides network services to the user’s

application– User interface– Examples – Telnet, HTTP, Web browsers

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Functions of Layer 6

• Presentation Layer: Data Representation–Ensures that the information that the application

layer of one system sends out is readable by the application layer of another system

–How data is presented–Special processing, such as data format,

compression and encryption

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Functions of Layer 5

• Session Layer: Interhost Communication–Establishes, manages, and

terminates session between two communication host.

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Functions of Layer 4

• Transport Layer: End-to-End Connection– How reliable transport between two hosts is

accomplished is the concern of the transport layer.

– Reliable or unreliable delivery– Examples: TCP, UDP

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Functions of Layer 4

• TCP breaks large data into segments

• TCP marks each data packet with a sequence number

• A missing packet can be resent

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Functions of Layer 3• Network Layer: Address and Best Path

– Provides connectivity and path selection between two host systems that may be located on geographically separated networks

– Provides logical addressing which routers use for path determination

– Examples: IP

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Functions of Layer 2

• Data Link Layer: Access to media– Concerned with physical (as opposed

to logical) addressing– Access to media using MAC address– Error detection

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Functions of Layer 1

• Physical Layer: Binary transmission–Moves bits between devices

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The Seven Layers of the OSI Reference Model

• The application (upper) layers– Layer 7: Application– Layer 6: Presentation– Layer 5: Session

• The data-flow (lower) layers– Layer 4: Transport– Layer 3: Network– Layer 2: Data link– Layer 1: Physical

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OSI Model and TCP/IP Model

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TCP/IP Protocol Graph

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Use of the OSI Model in the CCNA Curriculum

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Encapsulation The lower layers use encapsulation to put the protocol data unit (PDU) from the upper layer into its data field and to add headers and trailers that the layer can use to perform its function.

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Names for Data at Each Layer

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De-Encapsulation

• When the data link layer receives the frame, it does the following:–It reads the physical address and

other control information provided by the directly connected peer data link layer.

–It strips the control information

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Cisco Academy 3 References

• CCNA1 Online Materials– Slide 2 – 17 : 1.2.2 -1.2.9– Slide 18 – 23 : 2.1.5 – 2.1.7– Slide 25 - 29 : 2.2.1 – 2.2.3– Slide 30 – 45 : 2.3.2 – 2.3.7

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Cisco Academy 4 Exploration Reference

• Networking Fundamentals– Slide 2 – 17 : 6.1.1 – 6.1.4– Slide 18 – 23 : 2.1.6 – 2.2.3– Slide 25 – 29 : 2.3.2 – 2.4.2– Slide 30 – 45 : 2.4.1 – 2.4.8