Transcript CCNA1 3.0-02 Intro to Networking

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:
•
•
•
– plays multimedia files,
created by Macromedia Flash
Quicktime
– plays video files, created by Apple
Real Player – plays audio files
Flash
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
100
50
25
12
6
3
1
/
/
/
/
/
/
/
/
2
2
2
2
2
2
2
2
= 100 remainder 1
= 50 remainder 0
= 25 remainder 0
= 12 remainder 1
=
6 remainder 0
=
3 remainder 0
=
1 remainder 1
=
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
128
26
64
25
32
24
16
23
8
22
4
21
2
20
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 Binary
Convert 0x7A1D9F to Binary
7
A
1
D
9
F
0111 1010 0001 1101 1001 1111
0x7A1D9F =
0111101000011101100111112
Convert
111101000011101100111112 to Hex
0111 1010 0001 1101 1001 1111
7
A
1
D
9
F
0111101000011101100111112 =
0x7A1D9F
Binary
Hex
0000
0001
0010
0011
0100
0101
0110
0111
1000
1001
1010
1011
1100
1101
1110
1111
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
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 Masks
When 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 32bit IP address identify a particular host computer on the network.
Subnet Masks
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.
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 255.0.0.0
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 255.0.0.0 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 255.255.0.0
Converting 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.