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DCN286
INTRODUCTION TO DATA
COMMUNICATION TECHNOLOGY
Network Basics Introduction
Instructor: Ataur Rahman
[email protected]
Hardware
 It is usually referred to physical equipment
and/or components
 Computer usually has
Input device (scanner, keyboard and mouse);
 Processing unit (the computer CPU);
 Storage Devices (RAM,ROM, Hard Drive)
 Output device (printer, monitor)
In the computer box
A computer main components are:
Motherboard: or named as mainboard, everything would
be put on it.
CPU: the heart of the computer.
Memory: show room of data access, and usually
measured in MB, GB
Hard drive: warehouse (storage place) of data, file and
folders and usually measured in GB and TB now.
Function cards: video card, sound card (or called audio
card), modem, NIC (network interface card), and other
extension or adaptor cards
Case and power supply
Computer types
Server and workstation
Desktop and laptop
Terminal and kiosk
The major manufacturers:
Dell, HP, Lenovo, Apple, Acer, Toshiba, LG,
Asus.
Software
Three major categories:

Operating System:
i)
ii)
iii)
iv)
Microsoft Windows XP, Vista, Win7 2003 server, 2008 server,
Unix OS: Sun Solaris, IBM Unix, HP-UX
Linux OS: Red Hat, SUSE, Centos, Fedora, Ubuntu
Mac OS

Application programs:
Accounting software: Simply accounting, Accpac, Ceridian and APD
payroll software,
Law software: Conveyancer, PC Law, Amicus, AbacusLaw,
Database: Oracle, MS SQL server, My SQL,
Office software: word processing, spreadsheet and PowerPoint
presentation
Games and other programs

Device Driver
Used to communicate between hardware and OS/users.
Where to get information?
Personal education
Online or employer offered training
Friends
Professionals
Internet
Library
Manufacturer hotline
Computer network
Devices are connected together to share
resource and exchange information.
*Resources could be hardware, software,
data files, pictures and video.
*Exchange information could be online
chatting and messaging, email, blogging
and video or audio conference
Networking Devices
Starts from two computers
Two computers can be connected directly
via cross-over network cable. The cable
will connect to NIC (Network Interface
Card for which many people call it
“network card”) of the computers.
It was popular to share printer and files in
the past. But, it is still practical to copy
documents from your office or home
desktop to your laptop.
Multiple computers
In your office or in our classroom, many computers will be
connected together.
The collective connector would be a hub, switch and router.
Each computer (host) will be connected to
hub/switch/router by network cable.
LAN (Local Area Network): fast and reliable connect
computers together.
WAN (Wide Area Network): several LANs are linked via
remote connection.
Internet: The widest network composed by many websites
of companies and organizations.
Phone company and ISP
 Telephone service is one of the essential service offered
in North America.
 ISP (Internet Service Provider) offer the clients access to
internet.
Internet access services:
Rogers cable
Bell or other companies DSL service
Bell and/or other telecom ISDN service
T1/T3 connection
Dial up (less and less used now)
Wireless internet access offered via cell and satellite
Remote access
1. Dedicated connection (could be a
physically dedicated line or a leased line)
between offices
2. VPN (Virtual Private Network)
VPN is a tunnel built in the high speed
internet connection. The message
transferred via VPN is encrypted and
authenticated to protect confidentiality.
3. Modem is still used for standby remote
monitor connection.
Analog and digital (1)
Analog: simulate the original signal from the source. It may
lose the quality after repeated coping. It usually
demands good connection so as to maintain the
communication quality. The background noise may
significantly change the information while transmitting
them.
Digital: interpret the information as 1 (on) and 0 (off)
according to a protocol on the sender side, transmit such
signal over electrical signal over lines/cables and convert
those on/off electric signals back to information based on
the same rules. It can tolerate low-quality transmission
because relative high signals are also considered as “on”
and relative low signals are treated as “off”.
ASCII
 American Standard
Code for Information
Interchange is used to
interpret letters,
numbers and symbols
into 1 and 0:
Letter Binary
Decimal
A
01000001
65
B
01000010
66
C
01000011
67
D
01000100
68
E
01000101
69
F
01000110
70
G
01000111
71
H
01001000
72
Analog and digital (2)
Dial up is to use analog phone line.
ISDN and DSL are using digital phone line.
Telephone itself can work on either analog
or digital phone system because
manufacturers offer the compatibility.
Dial up must initiate connect by user. DSL
would be “turned on” by ISP.
TCP/IP Protocol
Think the protocol as “working language
over the network”
TCP/IP is the industry standard and the
only working protocol of internet.
TCP/IP is the name of a group of
protocols. Many protocols are working
together in the TCP/IP family.
Server/Client
 In general, each network device is a node and
all nodes are linked by cables in the network.
 Sometimes, we also use terminology “host”
 Server: whichever host offers service to other
hosts. Such as printer server, file server, web
server, mail server, and ftp server.
 Client: whichever host receive/retrieve/use
services from servers.
Web server, client and browser
Web server:
 The physical computer contains web pages of your
website. It can be accessed by website name or IP
address
Web client:
 Your computer is a web client while it visits different
websites. The computer will retrieve web pages from
web server.
Web browser:
 It is the program to display web page and download files
such as Microsoft Internet Explorer, Firefox, Netscape,
and Opera.
HTTP, HTML and editor
HTTP (Hypertext Transfer Protocol) is the
protocol.
HTML (Hypertext Markup Language) is the
language to compose web pages.
HTML editor is the program to compose
webpage in HTML. It could be notepad,
MS Word, Frontpage, Dreamweaver,
Homesite, HTML Editor.
Multimedia and plug-in
Flash player, Adobe reader and
shockwave player are examples of
application programs to display/play
various format files.
Plug-in is that the program would be
running “embedded” in another main
program.
Domain Name
 Domain name is identification name in internet. It
has a tree branch structure. Its format is
sub_domain.2nd_level_domain_name.1st_level_
domain_name.top_level_domain_name such as
support.office.microsoft.com
 Top level domain name:
Traditional .org, .com, .net, .gov, .edu,
Country code: .ca, .uk, .jp, .it
New name: .asia, .lib, .info, .jobs, .museum
 Hostname is the computer or equipment name.
 FQDN (Full Qualified Domain Name) will be the
combination of the host name and domain name
TCP/IP model
Application
Application
Presentation
Session
Transport
Transport
Internet
Network
Network Interface
Data Link
Physical
MAC address and IP address
 MAC address: It is also called physical address.
It is “burned” on the NIC by the manufacturer
and usually cannot be changed. Its format is 48
bits and usually displayed in hex such as 00-5056-C0-00-01.
 IP address: It is also called logical address as it
is assigned by network administrator or user. IP
V4 is the main protocol in North America and its
formation is presented as 192.168.2.200. IP
address is used to identify hosts in the network.
IP address
1. Traditionally, the IP address was classified in classes:
Class A: network 1 – 126 (Network 127 is reserved for
loopback and internal testing)
Class B: network 128 – 191
Class C: network 192 – 223
Class D: network 224 - 239 (Reserved for multicast)
Class E: network 240 – 255(Reserved for Experimental,
used for research)
2. There are public IP address used in Internet and private
IP address used in company/organization internal
networks.
Class A: 10.0.0.0 -10.255.255.255
Class B: 172.16.0.0 – 172.31.255.255
Class C: 192.168.0.0 – 192.168.255.255
Routing
If all traffics are in the same LAN (subnet),
no routing is required. The computers talk
to each other over network cable directly.
In different LAN (subnet), the packet sent
from sender must be “redirected” (routed)
to another network in which the recipient is
located.
Useful commands
Ipconfig
Ping
Tracert
Nslookup
Shutdown
Help
Troubleshooting procedures
1. Know the facts and collect background
information
2. Isolate the problem affected range
3. Document with time stamp
4. Start diagnose
5. Prepare solutions and try simple one
first. (Over thinking will waste your time
and over-correction may disable whole
network).
Bit, Byte, KB, MB, GB and TB
 Computer is working with electrical components.
It does not understand human language. It
would translate all characters, numbers and
symbols into signal of 1 (on or high) and 0 (off or
low).
 Bit is the signal unit with value of 1 or 0.
 Byte is 8 bits
 KB is 1000 (in fact, 1,024) Byte
 MB = 1000 (in fact, 1,024) KB
 GB is 1000 (in fact, 1,024) MB
 TB = 1000 (in fact, 1,024) GB
Network math
 Decimal (base 10)
numbering system
 Hexadecimal (base
16) numbering
system
 Binary (base 2)
numbering system
0
0
0
1
1
1
2
2
10
3
3
11
4
4
100
5
5
101
6
6
110
7
7
111
8
8
1000
9
9
1001
10
a
1010
11
b
1011
12
c
1100
13
d
1101
14
e
1110
15
f
1111
16
10
10000
Binary convert to Decimal (1)
Binary value:
00000000001
00000000010
00000000100
00000001000
00000010000
00000100000
00001000000
00010000000
00100000000
01000000000
10000000000
Pre-list following:
2^0 = 1
2^1 = 2
2^2 = 4
2^3 = 8
2^4 = 16
2^5 = 32
2^6 = 64
2^7 = 128
2^8 = 256
2^9 = 512
2^10 = 1024
Converting Decimal numbers to
8-bit Binary Numbers
Conversion Exercise
Use the example below to convert the decimal
Number 168 to a binary:
 128 fits into 168, so the left most bit in the binary
number is a 1, 168 – 128 leaves 40.
 64 does not fit into 40, so the second bit in from
the left is a 0.
 32 fits into 40, so the third bit in from the left is a 1,
40 – 32 leaves 8.
 16 does not fit into 8 so the forth bit in from the left
is a 0.
 8 fits into 8, so the fifth bit in from the left is a 1,
8 – 8 leaves 0, so the remaining bits to the right
are all 0.
Result: Decimal 168 = 10101000
Pre-list :
2^0 = 1
2^1 = 2
2^2 = 4
2^3 = 8
2^4 = 16
2^5 = 32
2^6 = 64
2^7 = 128
2^8 = 256
2^9 = 512
2^10 =1024
2^11 =2048
Convert binary to decimal
From the “1”’s position, pick up
corresponding decimal number value
and add all together.
Let’s calculate 101101101111:
The first “1” has 11 numbers at right hand
and it means 2^11=2048.
The next 1 has 9 numbers on right hand
and it is 2^9=512 ……
…..
Add up all:
2048+512+256+64+32+8+4+2+1=2927
Thus, 101101101111  2927
Pre-list :
2^0 = 1
2^1 = 2
2^2 = 4
2^3 = 8
2^4 = 16
2^5 = 32
2^6 = 64
2^7 = 128
2^8 = 256
2^9 = 512
2^10 =1024
2^11 =2048
Boolean calculation
1 means true
0 means false
Subnet Mask
Subnet mask is to divided IP address into two
sections: network ID and host ID.
Say the IP address is 192.168.4.64 with subnet mask
255.255.255.0:
Translate all decimal into binary:
IP address would be
11000000.100101000.00000100.01000000
Subnet mask would be
11111111.11111111.11111111.00000000
Final result:
Network id: 11000000.100101000.00000100 which
equals to 192.168.4
Host id: 01000000 meaning 64
Valid subnet mask value
 0  00000000
 128  10000000
 192  11000000
 224  11100000
 240  11110000
 248  11111000
 252  11111100
 254  11111110
 255  11111111
Question
Any question?
If you do not have question, please practice
conversion calculation between binary and
decimal numbering system.
1. Please convert decimal value 123, 240 and
255 to 8 bits binary.
2. Please convert binary value 11001101,
10010011 and 00110011 into decimal value.