Giáo trình CCNA - Chương 1

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
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 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
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
–10
3
= 10 X 10 X 10 = 1000
–2
4
= 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.
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
2
7
2
6
2
5
2
4
2
3
2

2
2
1
2
0
1286432168421
11001101
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 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)
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
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
Networking Devices
• Equipment that connects directly to a network segment
is referred to as a device.
• There are 2 type of devices: end-user devices and
network devices.
Network Devices
• 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

Network Topology
• The physical topology, which is the actual
layout of the wire or media.
• The logical topology, which defines how the
media is accessed by the hosts for sending
data.
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)
• A MAN is a
network that spans
a metropolitan
area such as a city
or suburban area.
• A MAN usually
consists of two or
more LANs in a
common
geographic area.