MTN 2013 Computer Network Technology

Chapter 1Introduction

Part I

04/10/2023 MTN 2013 3

Outline

1. Communication Concept2. Data Communications3. Computer and Data Communications4. Component of Communication Data System

04/10/2023 MTN 2013

1. Communication Concept

4

04/10/2023 MTN 2013 5

• Communication – exchange of information between two humans

• Data communication - exchange of information between two computers

04/10/2023 MTN 2013

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

6

TelecommunicationData

Communication

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 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)

04/10/2023 MTN 2013 14

4. Component of Communication Data System

• Sender• Receiver• Message• Transmission Medium• Protocol

04/10/2023 MTN 2013 15

Sender ReceiverTransmission Medium

Message

Step 1:..

Step 2:.

…..

Protocol Protocol

Step 1:..

Step 2:..

…..

-Information data

which is connected

e.g. image, sound, video-Devices that

send the messages

e.g. computer,telephone,

video camera

-Devices that receive

the message

e.g. computer, video camera,

telephone

-physical path over which data travels from the

Sender to receiver

e.g. wire, network,

radio waves

-A set of rules in data

-communications

e.g. formal language

Part II

04/10/2023 MTN 2013 17

Outline

1. Computer Data Network Application2. Data Communication: Data Protocol3. Data Communication: Data Standard

04/10/2023 MTN 2013 18

1. Computer Data Network Application

E-mailSearchable Data (Web Sites)E-CommerceNews GroupsInternet Telephony (VoIP)Video ConferencingChat GroupsInstant Messengers Internet Radio

04/10/2023 MTN 2013 19

E-mail

• E-mail stands for Electronic Mail• Basically, allow user to compose and exchange

message

04/10/2023 MTN 2013 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.

04/10/2023 MTN 2013 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.

04/10/2023 MTN 2013 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.

04/10/2023 MTN 2013 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.

04/10/2023 MTN 2013 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.

04/10/2023 MTN 2013 25

Chat Groups

• Need to choose which group to join.

04/10/2023 MTN 2013 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.

04/10/2023 MTN 2013 27

Internet Radio

• Also known as web radio, net radio, streaming radio, e-radio.

• An audio service transmitted via the Internet.

04/10/2023 MTN 2013 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.

04/10/2023 MTN 2013 29

Transmission Control Protocol (TCP)

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 32

Host sun1.ftsm.ukm.my/etc/services

PORT

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 34

TCP

• Provides reliable transmission services• Uses port protocol for addressing process• Applications that depends on reliability

for example telnet, http, ftp etc.

04/10/2023 MTN 2013 35

TCP Header Format

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 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 BHost B receives A's SYN

2. Host B sends a SYNchronize-ACKnowledgementHost A receives B's SYN-ACK

3. Host A sends ACKnowledgeHost 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.

04/10/2023 MTN 2013 38

Three-way Handshake

04/10/2023MTN 2013

39

Four-way Handshake - End the TCP Connection

• TCP use FIN segment to end the connection

• Four-way Handshake

04/10/2023 MTN 2013 40

User Datagram Protocol (UDP)

04/10/2023 MTN 2013 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]

04/10/2023MTN 2013

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

04/10/2023 MTN 2013 43

Internet Protocol (IP)

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 45

Figure 19.2 Links in an internetwork

04/10/2023 MTN 2013 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.

04/10/2023 MTN 2013 47

Figure 19.4 Network layer at the source

04/10/2023 MTN 2013 48

Figure 19.5 Network layer at a router

04/10/2023 MTN 2013 49

Figure 19.6 Network layer at the destination

04/10/2023 MTN 2013 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)

04/10/2023MTN 2013

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

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 53

Address Range to Identify Address Class

04/10/2023 MTN 2013 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.

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 56

Figure 19.19 A network with two levels of hierarchy

04/10/2023 MTN 2013 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.

04/10/2023 MTN 2013 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)

04/10/2023MTN 2013

59

Subnet

A campus network consists of LAN for the departments

04/10/2023 MTN 2013 60

Figure 19.20 A network with three levels of hierarchy (subnetted)

04/10/2023 MTN 2013 61

Figure 19.21 Addresses in a network with and without subnetting

04/10/2023MTN 2013

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

04/10/2023 MTN 2013 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.

04/10/2023MTN 2013

64

Example of Routing Tablenetstat -nr

$ netstat -nr

Routing Table: IPv4 Destination Gateway Flags Ref Use Interface-------------------- -------------------- ----- ----- ------ ---------202.185.46.0 202.185.46.197 U 1 25591 hme0224.0.0.0 202.185.46.197 U 1 0 hme0default 202.185.46.254 UG 1 80525 127.0.0.1 127.0.0.1 UH 3 137862 lo0

04/10/2023 MTN 2013 65

Figure 19.31 Default routing

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 68

Diagnostic Tools

• ipconfig (at microsoft) • ifconfig -a (at *nix)

– Show IP number, subnet and computer gateway

04/10/2023 MTN 2013 69

Domain Name System(DNS)

04/10/2023 MTN 2013 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)

04/10/2023 MTN 2013 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.

04/10/2023 MTN 2013 72Chapter 12: The Internet 72

04/10/2023 MTN 2013 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.

04/10/2023 MTN 2013 74

04/10/2023 MTN 2013 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

04/10/2023 MTN 2013 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)

Q&A

END