Giáo trình CCNA - Chương 1

Connecting to the InternetRequirements for Internet Connection • Connection to the Internet can be broken down into the following: – Physical connection : used to transfer signals betwee

CCNA – Semester1

Module 1 Introduction to Networking

Objectives

• Network physical connection

• Basic computer components

• Network math and IP address concept

Connecting to the Internet

Requirements for Internet Connection

• Connection to the Internet can be broken down into the following:

– Physical connection : used to transfer signals between PCs within the local network and to remote devices on the Internet

– Logical connection : uses standards called protocols A protocol is a formal description of a set of rules and conventions that govern how devices on a network communicate

– The application : interprets the data and displays the information in an understandable form

Network Interface Cards

• When you select a network

card, consider the following

three factors:

– Type of network – Type of media – Type of system bus

• A network interface card (NIC) is a printed circuit board that provides network communication capabilities to and from a personal computer

Modem

• A modem, or

modulator-demodulator, is a device that

provides the computer with

connectivity to a telephone line

• The modem converts (modulates)

the data from a digital signal to an

analog signal that is compatible

with a standard phone line

NIC and Modem Installation

• Connectivity to the Internet

requires an adapter card,

which may be a modem or NIC

• Notebook computers may have

a built-in interface or use a

PCMCIA card Desktop

systems may use an internal

or external NIC.

High-Speed and Dialup Connectivity

• By the 1990s modems were running at 9600 bps and reached the current standard of 56 kbps (56,000 bps) by

1998

• High-speed services used in the corporate environment, such as Digital Subscriber Line (DSL) and cable modem access, moved to the consumer market.

• These services no longer required expensive equipment

or a second phone line These are " always on " services that provide instant access and do not require a

connection to be established for each session

TCP/IP Description and Configuration

• Transmission Control

Protocol/Internet Protocol (TCP/IP)

is a set of protocols or rules

developed to allow cooperating

computers to share resources

across a network

• To enable TCP/IP on the

workstation, it must be configured

using the operating system tools

Testing Connectivity with Ping

• Ping is a program that is useful for verifying a successful TCP/IP installation

• It works by sending multiple packets to a

specified destination requesting for replies

Ping Command

• ping 127.0.0.1- This ping is unique and is called an internal

loopback test It verifies the operation of the TCP/IP stack and NIC transmit/receive function

• ping IP address- A ping to a host PC verifies the TCP/IP address configuration for the local host and connectivity to the host

Web Browser and Plug-Ins

• Web browsers acts on behalf

• Plug-ins is to view special, or

proprietary, file types that

standard web browsers are not

able to display

– Flash/Shockwave, QuickTime,

Real Audio

Network math and IP address

Binary presentation of data

• Computers operate with electronic switches that are either "on" or "off", corresponding to 1 or 0

• Computers have to translate in order to use decimal

numbering

Number Systems

• Knowing what base someone refers to

– Decimal uses 10 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9.

– Binary uses 2 digits: 0 and 1.

• Base conventions

– 101 in base 2 is spoken as one zero one.

• Working with exponents

1000011 1001001 1010000 1010100

?

Bits and Bytes

• 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

Base 10 Numbers

Example

Base 2 (Binary) Numbers

Converting Decimal to Binary

• 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

Converting Binary to Hexadecimal

• Remember that hexadecimal is sometimes abbreviated 0x so hex 5D might

be written as "0x5D"

Four-Octet Dotted-decimal Representation of

32-Bit Binary Numbers

• Currently, Internet Protocol (IP) addresses assigned to computers on the Internet are 32-bit binary numbers

• The 32-bit binary addresses used on the Internet are referred to as Internet Protocol (IP) addresses.

IP Addresses and Network Masks

• The IP address of a computer usually consists of a

network, and a host part that represents a particular computer on a particular network

• Subnetwork mask a second 32-bit number to identify how many of the IP address bits are used to identify the network of the computer

• A subnet mask will always be all 1s until the network address is identified and then be all 0s from there to the right most bit of the mask

SubnetMask Example

• Converting the IP address 10.34.23.134 to binary

would result in:

00001010.00100010.00010111.10000110

• Performing a Boolean AND of the IP address

10.34.23.134 and the subnet mask 255.240.0.0 produces the network address of this host:

00001010.00100010.00010111.10000110 Æ 10.34.23.134 (IP address)

11111111.11110000.00000000.00000000 Æ 255.240.0.0 (subnetmask)

00001010.00100000.00000000.00000000 Æ 10.32.0.0 (subnetwork address)

View computer address

• ipconfig /all : detail IP configuration

• ipconfig /renew : renew IP address with DHCP

• Practise IP and subnetmask

• The physical connection that has to take place for a computer to connect to the Internet

• Network interface cards and/or modems

• Web browser selection and configuration

• The Base 2 number system

• Binary number conversion to decimal

• Representasion of IP addresses and network masks

Module 2 Networking Fundamentals

Objectives

• Networking terminology

• Some network architectures

• The importance of bandwidth

• Networking models: OSI vs TCP/IP

Networking Terminology

Relative size of network

• Repeater: regenerate a signal

• Hub: concentrate connections and may

regenerate a signal.

• Bridge: convert network transmission

data formats as well as perform basic

data transmission management

• Switch: add more intelligence to data

transfer management

• Router: routing and other services

Physical Topology

Logical Topology

Broadcast

Token Passing

Logical Topology: Broadcast

• Each host sends its data to all other hosts on

the network medium.

• First-come, first-serve.

• Eg: Ethernet

Logical Topology: Token Passing

• Access to media is controlled by an electronic token.

• Possession of the token gives the host the right to pass data to its destination.

• Eg: Token-Ring, FDDI

Network Protocols

• Protocol suites are collections of protocols

that enable network communication from one host through the network to another host

• A protocol is a formal description of a set of

rules and conventions that govern a particular aspect of how devices on a network

communicate

Functions of Protocols

• Protocols control all aspects of data

communication, which include the following:

– How the physical network is built

– How computers connect to the network

– How the data is formatted for transmission

– How that data is sent

– How to deal with errors

LANs

• Operate within a limited geographic area

• Allow many users to access high-bandwidth

media

• Provide full-time connectivity to local services

• Connect physically adjacent devices

LAN Devices and Technology

• Some common LAN technologies are:

– Ethernet

– Token Ring

– FDDI

WANs

• Operate over a large geographically separated areas

• Provide full-time remote resources connected to local services

WAN Technologies Include

• Some common WAN technologies are:

– Analog modems

– Integrated Services Digital Network (ISDN)

– Digital Subscriber Line (DSL)

– Frame Relay

– Asynchronous Transfer Mode (ATM)

– T (US) and E (Europe) carrier series: T1, E1, T3, E3

– Synchronous Optical Network (SONET)

Metropolitan-Area Networks (MANs)

Storage-Area Networks (SANs)

• A SAN is a dedicated,

high-performance

network used to move

data between servers

and storage resources

Virtual Private Networks (VPNs)

the global Internet

• VPN is the most

cost-effective method of

establishing secured

connection

Importance of Bandwidth

Digital Bandwidth

• Bandwidth is the measure of how much

information, or bits, can flow from one place to another in a given amount of time, or seconds

Bandwidth Limitations (LAN)

Bandwidth Limitations (WAN)

• Throughput refers to actual measured

bandwidth , at a specific time of day, using specific Internet routes, and while a specific set of data is transmitted on the network.

• Factors that determine throughput:

Data Transfer Calculation

Calculate an estimate of network performance

What different forms flow ?

Text, Graphic, Video

What rules govern flow ? Standard, Protocol

What rules govern flow ?

Destination Address Medium

Evolution of networking standards

Why a layered model

7 layers of the OSI reference model

Network processes to applications Data representation

Interhost communication End-to-end connections Address and best path

Direct link control, a

Direct link control, access to media Binary transmission

•A ll P eople S eem T o N eed D ata P rocessing

Network processes to applications

7 layers of the OSI reference model

• Is the OSI layer that is closest to the user; it provides network services to the user’s

applications.

– File transfer – Electronic mail – Terminal access – …

Data representation

7 layers of the OSI reference model

• Ensures that the information that the application layer of one

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

– Format of data – Data conversion – Data compression – Data encryption

7 layers of the OSI reference model

• Establishes, manages, and terminates sessions between two communicating hosts

– Sessions – Dialog – Conversations – Data exchange

Interhost communication

End-to-end connections

7 layers of the OSI reference model

• Provides reliable, transparent transfer of data over networks.

– Segments, data stream, datagram – End-to-end flow control

– Error detection and recovery – Segmentation & reassembly – …

Address and best path

7 layers of the OSI reference model

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

– Packets – Route, routing table, – Logical address – Fragmentation – …

Direct link control,

Direct link control, access to media

7 layers of the OSI reference model

• Provides for the reliable transfer

of data cross a physical link.

– Frames – Physical address – Network topology – Line discipline – …

Binary transmission

7 layers of the OSI reference model

• Transmission of an unstructured bit stream over a physical link between end systems.

– Electrical, mechanical, procedural and functional specifications

– Physical data rate – Distances – Physical connector

7 layers of the OSI reference model

Network processes to applications Data representation

Interhost communication End-to-end connections Address and best path

Direct link control, a

Direct link control, access to media Binary transmission

•A ll P eople S eem T o N eed D ata P rocessing

Peer-to-Peer Communication

• The protocols of each

layer exchange

information, called

protocol data units

( PDUs ), between peer

layers

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.

• 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 from the frame, thereby creating a datagram.

– It passes the datagram up to the next layer, following the

instructions that appeared in the control portion of the frame.

Encapsulation example: E-mail

Layer-to-layer communications

Request services Provide services

TCP/IP model development

• The late-60s The Defense Advance

Research Projects Agency (DARPA)

originally developed Transmission Control Protocol/Internet Protocol (TCP/IP) to

interconnect various defense department computer networks.

• The Internet, an International Wide Area

Network, uses TCP/IP to connect networks across the world.

The TCP/IP Reference Model

name as layers in the OSI model

Do not confuse the layers of the two models

TCP/IP Protocol Stack

OSI Model and TCP/IP Model

Focus of the CCNA Curriculum

• Networking devices

• Some of the common network types

• Intranet and extranet

• Bandwidth and throughput

• The layered communication model

• OSI reference model

• TCP/IP networking model

Module 3 Networking Media

Objectives

• Copper media and electronic signal

• Optical media and light signal

• Wireless media and wave

Copper Media

Electricity Basics

The basic unit of all

matter is an atom.

– Protons – particles that

have positive charge

– Neutrons – particles that

have no charge (neutral)

– Electrons – particles that

have negative charge and

orbit the nucleus

Static electricity

• Electrons have been

loosened from the atom

and stay in one place,

without moving.

• Electrostatic discharge

(ESD).

– ESD, though usually

harmless to people, can

create serious problems for

sensitive electronic

equipment.

free electron

Measuring electricity: Current

• The flow of charges that is created when

electrons move.

• Symbol: I

• Ampere (A).

Electrical definitions: AC and DC

• Alternating Current (AC):

– Electrical current flows in both directions; positive and negative terminals continuously trade places (polarity).

– Electrical current flows in one direction; negative to

positive.

Measuring electricity: Resistance

• Resistance: property of a material that opposes the electrical flow

• Resistance consume electrical energy and cause attenuation.

Measuring electricity: Voltage

• Force or pressure caused by the separation of electrons and protons

Cable Specifications

• What speeds for data transmission can be

achieved using a particular type of cable?

• What type of transmission is being considered? Will the transmissions be digital or will they be analog-based?

• How far can a signal travel through a particular type of cable before attenuation of that signal becomes a concern?

Ethernet Specifications

Coaxial Cable

• If not properly grounded, shielding is very poor.

• Speed of transmission:10-100Mpbs

• Longer cable runs than UTP & STP.

• Maximum cable length :

– Thin cable : 185 m.

– Thick cable : 500 m.

• Impedance: 50Ω.

Shielded Twisted-Pair Cable

• Protection from all types of external interference, include EMI and RFI.

– Cancellation: twisting of wires.

Screened Twisted-Pair Cable

Cancellation

Unshielded Twisted-Pair Cable

• More prone to EMI/RFI interference than any other cable types.

• Least expensive of all media

– small diameter of cable (~ 43cm),