Requirements for an Internet Connection

The Internet is the largest data network on earth.

Connection to the Internet can be broken down into

• the physical connection- cables, NIC

• the logical connection, and - protocols: TCP/IP

• the application.- Web browser, FTP

PC Basics

Personal computers have several components

• Small Discrete Components- Transistor, IC, Resistor, LED

• Personal Computer Subsystems- PCB, CD-ROM, CPU, Disk Drives, RAM,- ROM, Bus, Microprocessor

• Backplane Components - Backplane, NIC, Audio Card, Video Card,- Power cord, and several ports

Network Interface Card

A network interface card (NIC) is a printed circuit board that provides network communication capabilities to and from a personal computer. Also called a LAN adapter.

NIC and MODEM Installation

Connectivity to the Internet requires an adapter card, which may be a modem or NIC.

A modem, or modulator-demodulator, is a device that provides the computer with connectivity to a telephone line. Modems can be installed internally or externally.

Every device on a network must have a NIC.

Overview Of High-Speed And Dial-Up Connectivity

In the 1960s MODEM were introduced with a baud rate of 300bps (bits per second).

BBS (Bulletin Board Systems) came out in th 1970s.

BBS use increased exponentially by the 1980s.Users wanted to transfer files and graphics.

In the 1990s MODEMs were improved to the 56kbps standard of today.

In 2000 DSL (Digital Subscriber Line) & Cable Modems also came out which are “always on” and do not require a dial-up for a connection to be established.

TCP/IP

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.

TCP/IP is configured using operating system tools.

Testing Connectivity with Ping

The Ping command can be used to test “connectivity” between 2 devices.

Example:

ping 172.16.0.13

Ping works by sending multiple “request for a reply” packets to a destination. If the replies return we know we are connected.

Web Browsers

A web browser performs the following functions:

• Contacts a web server • Requests information • Receives information • Displays the results on the screen

A web browser is software that interprets hypertext markup language (HTML), one of the languages used to code web page content.

Two of the most popular web browsers are Internet Explorer (IE) and Netscape Communicator.

Plug-Ins

There are also many special, or proprietary, file types that standard web browsers are not able to display.

To view these files the browser must be configured to use the plug-in applications. These applications work in conjunction with the browser to launch the program required to view the following special files:

• Flash – plays multimedia files, created by Macromedia Flash

• Quicktime – plays video files, created by Apple • Real Player – plays audio files

Trouble-Shooting Internet Connection Problems

Follow these steps:

Binary Representation of Data

Computers work with and store data using electronic switches that are either ON or OFF. 1 represents “ON” and 0 represents “OFF”. This is called Binary.

The American Standard Code for Information Interchange (ASCII) is the most commonly used code for representing alpha-numeric data in a computer.

Bits and Bytes

Base 10 Number System

2134 = (2x103) + (1x102) + (3x101) + (4x100)

Base 2 Number System

101102 = (1 x 24 = 16) + (0 x 23 = 0) + (1 x 22 = 4) + (1 x 21 = 2) + (0 x 20 = 0) = 22

Converting Decimal to Binary

Convert 20110 to binary:

201 / 2 = 100 remainder 1 100 / 2 = 50 remainder 0 50 / 2 = 25 remainder 0 25 / 2 = 12 remainder 1 12 / 2 = 6 remainder 0 6 / 2 = 3 remainder 0 3 / 2 = 1 remainder 1 1 / 2 = 0 remainder 1

When the quotient is 0, take all the remainders in

reverse order for your answer: 20110 = 110010012

Converting Binary to Decimal

Convert 110010012 to decimal:

27 26 25 24 23 22 21 20

128 64 32 16 8 4 2 1

1 1 0 0 1 0 0 1

Ignore the zeros. Find all of the ones and add up the corresponding powers of 2.

128 + 64 + 8 + 1 = 201

You should memorize this series of numbers!

4-Octet Decimal Dotted Notation

Currently, addresses assigned to computers on the Internet are 32-bit binary numbers. To make it easier to work with these IP (Internet Protocol) addresses, the 32-bit binary number is broken into 4 “octets” and converted into 4 decimal numbers.

Hexadecimal Numbers

Hexadecimal refers to a Base 16 number system.

This means there are 16 digits: 0 - 9 and A – F

Hexadecimal is used for a NIC’s MAC Address.

Hexadecimal is also used in Assembly Language and for memory addresses. Hex is abbreviated with 0x.

0x11A2B39F means the same thing as 11A2B39F16

The main reason base-16 is used is that converting between base-16 and base-2 is very quick.

Converting Between Hex and BinaryConvert 0x7A1D9F to Binary

7 A 1 D 9 F0111 1010 0001 1101 1001 1111

0x7A1D9F = 0111101000011101100111112

Convert 111101000011101100111112 to Hex

0111 1010 0001 1101 1001 11117 A 1 D 9 F

0111101000011101100111112 =0x7A1D9F

Binary Hex

0000 00001 10010 20011 30100 40101 50110 60111 71000 81001 91010 A1011 B1100 C1101 D1110 E1111 F

Boolean NOT Logic Gate

NOT will take return the opposite of what you give it.

Boolean OR Logic Gate

Requires one conditions to be true to return true.

Boolean AND Logic Gate

Requires both conditions to be true to return true.

IP Addresses and Network MasksWhen IP addresses are assigned to computers, some of the bits on the left side of the 32-bit IP number represent a network. The bits left over in the 32-bit IP address identify a particular host computer on the network.

Subnet MasksA 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.Some examples of subnet masks are:

11111111000000000000000000000000 written in dotted decimal as 255.0.0.0

or

11111111111111110000000000000000 written in dotted decimal as 255.255.0.0

10.34.23.134 AND 255.0.0.0Converting 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 255.0.0.0 produces the network address of this host:

00001010.00100010.00010111.10000110 11111111.00000000.00000000.00000000 00001010.00000000.00000000.00000000

Converting the result to dotted decimal, 10.0.0.0 is the network portion of the IP address, when using the 255.0.0.0 mask.

172.16.122.244 AND 255.255.0.0Converting the IP address 172.16.122.224 to binary would result in:

10101100.00010000.01111010.11100000

Performing a Boolean AND of the IP address 10.34.23.134 and the subnet mask 255.255.0.0 produces the network address of this host:

10101100.00010000.01111010.11100000 11111111.00000000.00000000.00000000 10101100.00010000.00000000.00000000

Converting the result to dotted decimal, 172.16.0.0 is the network portion of the IP address, when using the 255.255.0.0 mask.

NOTE TO STUDENTS:The methods of converting numbers shown in these slides are intentionally different from what is shown in the curriculum. Pick which ever method works for you.

Also, there is more to this subnetting issue.

We will spend more time going over number conversions and subnetting.