CCNA – Semester1

Module 1Introduction 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

Information flow

Case Study: Boot process

BIOS

OS

SHELL

User Interface

ROM RAM

HDD RAM

RAM IO

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 rulesdeveloped 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 of a user by– Contacting a web server– Requesting information– Receiving information– Displaying the results on a

screen• 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– 103 = 10 X 10 X 10 = 1000– 24 = 2 x 2 x 2 x 2 = 16

• Binary numbers– Use principle of place value just as decimal numbers do

ASCII

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

1000011100100110100001010100

?

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

27 26 25 24 23 22 21 20

128 64 32 16 8 4 2 1

1 1 0 0 1 1 0 1

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.

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.

SubnetMask

• 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 10.34.23.134 (IP address) 11111111.11110000.00000000.00000000 255.240.0.0 (subnetmask)

00001010.00100000.00000000.00000000 10.32.0.0 (subnetwork address)

Address Example

• IP address 10.34.23.134

• Subnetmask 255.0.0.0

• IP address:00001010.00100010.00010111.10000110 = 10.34.23.134

• Network address:00001010.00000000.00000000.00000000 = 10.0.0.0

• Broadcast address:00001010.11111111. 11111111. 11111111=10.255.255.255

View computer address

• ipconfig : brief IP configuration

• ipconfig /all : detail IP configuration

• ipconfig /renew : renew IP address with DHCP

• Practise IP and subnetmask

Summary

• 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