1. MTN 2013
Computer Network Technology
Chapter 1
Introduction

2. Part I

3. Outline
1. Communication Concept
2. Data Communications
3. Computer and Data Communications
4. Component of Communication Data System
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4. 1. Communication Concept
4
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5. • Communication – exchange of information
between two humans
• Data communication - exchange of
information between two computers
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6. 2. Data Communication
What is data communication?
Data communication is subset of telecommunication.
Telecommunication - Any process that permits the passage from
a sender to one or more receivers of information of any nature,
delivered in any easy to use form by any electromagnetic system
Data
Communication Telecommunication
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7. History of Telecommunications
• Invention of telegraph Samuel Morse – 1837
• Invention of telephone- Alexander Graham
Bell – 1876
• Development of wireless by Guglielmo
Marconi (develops the first wireless telegraph
system) – 1896
• Concept of universal access and growth of
AT&T
• Divestiture of AT&T— 1980s
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8. History of Telecommunications
..continued
• Telecommunications Act of 1996
• Three main developments that led to the growth of
data communications systems:
– Large-scale integration of circuits reduced the cost and size
of terminals and comm equipment
– Developments of software systems made establishment of
communication networks easy
– Competition among providers of transmission facilities
reduced the cost of data circuits
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9. Not to be confused with telecommunication—
Data communication -
Defined as a subset of telecommunication involving the
transmission of data to and from computers and
components of computer systems
>> Focus is on the transmission medium, different signal levels
and data coding
>> More specifically data communication is transmitted via
mediums such as wires, coaxial cables, fiber optics, or radiated
electromagnetic waves such as broadcast radio, infrared light,
microwaves, and satellites
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10. History of Data Communication
• Transistor developed by Bell Labs in 1947
• Hush-a-Phone Case
• Carter phone case
• MCI and Long Distance
• Creation of networks (LAN’s and WAN’s)
• Data Link Protocols
• Microcomputers
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11. 3. Computer & Data Communications
• Data communications involves the exchange of data between two
computers
• Computers work with a binary language consisting of zero and
one (0 and 1)
• Therefore, a computer generates a stream of zeroes and ones and
send it to another computer to which it is connected
• The connection can be either a simple wire or can be through
wireless media
• It is not necessary for these two computers to be close to each
other – different rooms, cities, states, countries, continents
• For enabling data communications, a combination of software
and hardware is essential
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12. ..continued
• In any data communications system, three
characteristics are desired:
i. Correct delivery – when sender transmits data for an
intended recipient, the data must reach only the intended
recipient and not someone else
ii. Accurate delivery – the data sent must be received in
the same form as the one in which it was sent. There must not
be any sort of alterations to it in transit
iii. Timely delivery – the data must travel from the sender
to receiver in a finite amount of time. The term finite is quite
vague, and would depend on the reasons why the data
communications is taking place
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13. ..continued
• Two key aspects of data communications:
i. Transmission medium – physical path over which
data travels from the sender to receiver (e.g. copper wires,
coaxial cables, optical fiber or wireless media such as radio
waves)
ii. Data communications protocols – set of rules
and conventions (standard)
*We will discuss these two topics in detail later (next chapters)
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14. 4. Component of Communication
Data System
• Sender
• Receiver
• Message
• Transmission Medium
• Protocol
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15. -A set of rules in
data
-communications
Step 1:.. -Information Step 1:.. formal
e.g.
Step 2:. data Step 2:.. language
which is
….. -physical path …..
connected
over which data
Protocol travels from the Protocol
e.g. image,
Sender to
-Devices that sound, video
receiver
send the -Devices that
messages
Message receive
e.g. wire,
network, the message
e.g. computer, radio waves
telephone, e.g. computer,
video video camera,
camera
Transmission Medium telephone
Sender Receiver
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16. Part II

17. Outline
1. Computer Data Network Application
2. Data Communication: Data Protocol
3. Data Communication: Data Standard
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18. 1. Computer Data Network
Application
E-mail
Searchable Data (Web Sites)
E-Commerce
News Groups
Internet Telephony (VoIP)
Video Conferencing
Chat Groups
Instant Messengers
Internet Radio
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19. E-mail
• E-mail stands for Electronic Mail
• Basically, allow user to compose and exchange
message
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20. Searchable Data (Websites)
• A collection of related web pages containing
images, videos or other digital assets.
• Display organization info and medium of
communication.
• Two categories; a. static & b. dynamic website.
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21. E-commerce
• Electronic Commerce (eCommerce or e-comm)
• Consists of the buying and selling of products or
services over electronic systems such as the
Internet and other computer networks.
• It also includes the entire online process of
developing, marketing, selling, delivering,
servicing and paying for products and services.
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22. Newsgroup
• A newsgroup is a discussion about a particular
subject consisting of notes written to a central
Internet site and redistributed through
Usenet, a worldwide network of news
discussion groups.
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23. Internet Telephony (VoIP)
• Communication protocols
• Transmission technologies for delivery of voice
communications and multimedia sessions
over Internet Protocol (IP) networks, such as
the Internet.
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24. Video Conferencing
• A set of interactive telecommunication
technologies which allow two or more
locations to interact via two-way video and
audio transmissions simultaneously.
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25. Chat Groups
• Need to choose which group to join.
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26. Instant Messengers
• A form of real-time direct text-based
communication between two or more people
using personal computers or other devices,
along with shared clients.
• More advanced instant messaging software
clients also allow enhanced modes of
communication, such as live voice or video
calling.
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27. Internet Radio
• Also known as web radio, net radio, streaming
radio, e-radio.
• An audio service transmitted via the Internet.
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28. 2. Data Communication: Data
Protocol
• The Internet started out around 1969 as a kind
of science fair project by the U.S. military, and
it was known as the ARPANET. That network
no longer exists, but various protocols that
were invented for it are still in use.
• As the Internet user , a basic understanding of
what IP, TCP, and UDP, as well as DNS domain
names is very important.
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29. Transmission Control
Protocol (TCP)
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30. TCP
• Transmission Control Protocol/Transfer
Control Protocol/Transport Control Protocol
• TCP is the most widely used Internet protocol
• Transport layer protocol
– Transmit the message from server to client
– How client can achieve the server – inter-process
communication through port protocol
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31. Port Protocol
• Port protocol assigned to the process by
operating system
• There are 216 port (0 till 65535)
• 2 set of ports
– UDP protocol
– TCP protocol
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32. Host sun1.ftsm.ukm.my
/etc/services
PORT
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33. Port Protocol
• Port well-known (1 – 1023)
• For standard services
• HTTP [80], SMTP[25], FTP[21, 22], POP3[110], Telnet
[23]
• Ephemeral port (1024 – 65535)
• Dynamically allocated
• Assigned to the client process
• After the completion of client process, port will be
freed
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34. TCP
• Provides reliable transmission services
• Uses port protocol for addressing process
• Applications that depends on reliability
for example telnet, http, ftp etc.
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35. TCP Header Format
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36. TCP Connection
• TCP connection has been identified with the
end point (port number) of the connection
• To establish the TCP connection, it comprise
the two ways communication
• Client will make a request to the port at the
server
• Server will open the port and start the
connection
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37. Three-way Handshake –
Initiate TCP Connection
• TCP uses a three-way handshake to initiate the connection for reliability.
1. Host A sends a TCP SYNchronize packet to Host B
Host B receives A's SYN
2. Host B sends a SYNchronize-ACKnowledgement
Host A receives B's SYN-ACK
3. Host A sends ACKnowledge
Host B receives ACK.
TCP socket connection is ESTABLISHED.
•
TCP Three Way Handshake
(SYN,SYN-ACK,ACK)
• To make sure both nodes ready to adjust random sequence number for
synchronization.
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38. Three-way Handshake
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39. Four-way Handshake - End the TCP
Connection
• TCP use FIN segment to
end the connection
• Four-way Handshake
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40. User Datagram Protocol
(UDP)
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41. UDP
• Transport layer protocol
• Provides communication for unreliable connection
• Packet might be lost or not in sequence
• No buffer – receive data from application and
directly send it.
• Has been used when no error control needed.
• For the process like;
DNS [53], echo [7], tftp [69], SNMP[161]
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42. UDP Datagram Format
• Header
– UDP Source Port (16 bit)
– UDP Destination Port (16 bit)
– UDP Message Length (16 bit)
– UDP Checksum (16 bit)
• Data
UDP Source Port UDP Destination Port
UDP Message Length UDP Checksum
Data
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43. Internet Protocol (IP)
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44. IP
• Network layer protocol
• Provides packet transmission through seamless
communication.
• Use IP address for addressing
• Determine packet route through one ore more hop
• Provides mechanism consist of:
– Data unit (IP datagram)
– Software to transmit datagram
– Tips on how the computer host process the datagram
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45. Figure 19.2 Links in an internetwork
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46. IP
• IP is responsible to provide best-effort transmission
for packet/datagram
• How the communication through Internet ?
– Transport layer take the flow of data and break it to datagram
– Network layer transmits each datagram through Internet.
Splitting to the smaller unit might happen during this process
– At the destination, datagram will be assemble by network layer
d to the original datagram and will be sent to transport layer.
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47. Figure 19.4 Network layer at the source
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48. Figure 19.5 Network layer at a router
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49. Figure 19.6 Network layer at the destination
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50. Addressing
• Need standard address format
• Address format should not rely on hardware
address format
• Address must be unique in the whole network
(Internet)
• The body that control address registration –
Internet Information Center (InterNIC)
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51. IP Address (IPv4)
• Represent by 32-bits integer
• Use dotted decimal quad notation
– Consists of 4 parts of 8 bits
– Separated by full stops
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52. Network Class
• IP address has been organized based on network
class
– Class A: 0nnnnnnn.iiiiiiii.iiiiiiii.iiiiiiii
– Class B: 10nnnnnn.nnnnnnnn.iiiiiiii.iiiiiiii
– Class C: 110nnnnn.nnnnnnnn.nnnnnnnn.iiiiiiii
– Class D: 1110bbbb.bbbbbbbb.bbbbbbbb.bbbbbbbb
– Class E: for future use
• Representation:
– n – network number
– i – host number
– b – group id
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53. Address Range to Identify Address
Class
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54. • Each IP address has been divided into two
parts
– Network number(prefix) – shows physical network
to where the computer connected
– Host number(suffix) – shows computer unique
number in network
• Internet Corporation for Assigned Names and
Numbers (ICANN) responsibles to assign class
A, B and C to organization.
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55. • Class A, B and C are the primary class
– Use for normal host addressing
• Class D for multicast purpose,
– to broadcast message
• Class E reserved for future use
• Each host has virtual address interface known
as loopback interface that is 127.0.0.1
– Also known as localhost
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56. Figure 19.19 A network with two levels of hierarchy
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57. IP Address Weakness
• Some hosts have more than one IP address
• Network classes are too rigid
• There was not enough IP address for future
use.
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58. Subnet
• IP address has been organized as subnet to
simplify network management.
• Each subnet is address set determined by
– Subnet address (example: 199.17.35.96)
– Subnet mask (example: 255.255.255.240)
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59. Subnet
A campus network consists of LAN for the
departments
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60. Figure 19.20 A network with three levels of hierarchy (subnetted)
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61. Figure 19.21 Addresses in a network with and without subnetting
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62. Example of Subnet
For class B network:
• 3 bits have been used as subnet to become
15 subnet
– subnet mask: 255.255.224.0
• The other 13 bits represent host
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63. Routing
• If destination host not in the same network,
datagram will be sent to gateway.
• How IP choose route to transmit the datagram
to a remote network?
– By using routing table which has the information
on the next hop – other nodes directly connected
to the gateway.
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64. Example of Routing Table
netstat -nr
$ netstat -nr
Routing Table: IPv4
Destination Gateway Flags Ref Use Interface
-------------------- -------------------- ----- ----- ------ ---------
202.185.46.0 202.185.46.197 U 1 25591 hme0
224.0.0.0 202.185.46.197 U 1 0 hme0
default 202.185.46.254 UG 1 80525
127.0.0.1 127.0.0.1 UH 3 137862 lo0
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65. Figure 19.31 Default routing
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66. Internet Protocol Version 6 (IPv6)
• Known as Next Generation Internet Protocol
(IPng)
• Length of the address has been added to 128
bits
• Allow additional hosts on the Internet web
• Allow the development of Internet
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67. Diagnostic Tools
• ping
– test connection to host
– measure round trip time
• traceroute (at microsoft: tracert)
– Show the data route from host to destination
– http://www.traceroute.org/
• netstat -nr
– Show routing table
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68. Diagnostic Tools
• ipconfig (at microsoft)
• ifconfig -a (at *nix)
– Show IP number, subnet and computer gateway
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69. Domain Name System
(DNS)
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70. DNS
• DNS is a name and address database
• It is difficult for human to remember the IP address
• DNS provides translation between symbolic name
and IP address.
• Symbolic name consist of, sequence of alphanumeric
component which has been separated by full stop.
– example: www.ftsm.ukm.my , sun1.ftsm.ukm.my
• Name hierarchy:
– The far right shows the domain (example: ftsm.ukm.my)
– The far left shows the computer name (example: sun1, www)
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71. Domain Name
• The top domain name was determined
– example: com, net, org, my
• Company buy the name from InterNIC and
sell it to other company.
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72. 11/17/2011 MTN 2013 72
Chapter 12: The Internet 72

73. Name Mapping and IP Address
• An application program call the library procedure
(resolver), by sending the host name as parameter.
• Resolver send the UDP packet to local DNS server
• The server find the name and return the IP address
to resolver, and then to the caller.
• With the IP address, program can then make a TCP
connection to destination.
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74. 11/17/2011 MTN 2013 74

75. Tools
• hostname
– The name of computer
• domainname
– Name of domain
• nslookup
– Network and Server Information Tools from
Myloca (Telekom Malaysia)
http://www.myloca.net/cgi-bin/trace/index.pl
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76. 3. Data Communication:
Data Standard
Layer Common Standards
5. Application layer HTTP, HTML (Web)
MPEG, H.323 (audio/video)
IMAP, POP (e-mail)
4. Transport layer TCP (Internet)
SPX (Novell LANs)
3. Network layer IP (Internet)
IPX (Novell LANs)
2. Data link layer Ethernet (LAN)
PPP (dial-up via modem)
1. Physical layer RS-232c cable (LAN)
Category 5 twisted pair (LAN)
V.92 (56 kbps modem)
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77. END
Q&A