MAKERERE UNIVERSITY College of Computing and Information Sciences School of Computing and Informatics Technology

BIT 1102: COMMUNICATIONS BIT 1102: COMMUNICATIONS TECHNOLOGY AND THE INTERNETTECHNOLOGY AND THE INTERNET

8. The Internet Protocol Suite and the 8. The Internet Protocol Suite and the InternetInternet

Internet protocol Suite:

In this lecture, we discuss another model known as the TCP/IP Model, also known as the Internet Protocol suite.

This is a simplified and more widely implemented set of protocols than the OSI (Open Systems Interconnection) model.

The main difference between the OSI and the TCP/IP is the number of layers illustrated.

2

BIT 1102: Communications Technology & the Internet

TCP IP

Generally consists of 4 Layers.

Layer 4: Application

Layer 3: Transport

Layer 2: Network

Layer 1: Data Link Layer

3

BIT 1102: Communications Technology & the Internet

TCP / IP SUITE SUMMARY

4. Application A layer that communicates with the application. Protocols include: DNS, HTTP, FTP, DHCP,SMTP etc.

3. Transport Reliable end to end data delivery. TCP is connection oriented while UDP is connection less

2.Network (also known as the Internet work)

Implementation of IP Addresses to enable best effort transmission of packets through routing (Internet Protocol resides here)

1.Link (also known as the Network Access)

Defines physical features / type of network .Protocols include Ethernet, ATM, FDDI etc

4

BIT 1102: Communications Technology & the Internet

Qn:

Differentiate between the OSI and the TCP/IP reference models for communication and critique both models.

BIT 1102: Communications Technology & the Internet

5

DNS: An Introduction:

• Located at the application layer, the Domain Name System (DNS) is an important aspect of the Internet.

• DNS translates IP addresses into Human readable names known as domain names (and Vice versa) so that the user does not need to remember the thousands of numeric (IP) addresses on the Internet.

• For example, www.makerere.ac.ug could be 196.43.133.84.

• Imagine having to know each IP address of the website you’re going to visit!!!.

6

BIT 1102: Communications Technology & the Internet

DNS

Quick exercise:Find out the IP address of the following

Domain names.www.google.comwww.msn.comwww.trueafrican.com

HINT: Use the ping command in DOS and then

type the website name. Note the set of numbers that are sent back to your screen. Eg at DOS prompt, type PING Google.COM

7

BIT 1102: Communications Technology & the Internet

Internetworking - The Internet and the world wide web

Internetworking refers to the connecting of two or more distinct networks together.

One of the most prominent networks is the Internet.

TCP/IP is the architecture on which the Internet is based. This architectural model provides a common frame of reference for discussing Internet communications.

8

BIT 1102: Communications Technology & the Internet

The Internet

• The Internet is described by many as a “Network of networks”

• The Internet is made up of millions of computers connected together across the globe.

• As we discussed before, data across the Internet is transmitted via packed switching using the Internet protocol (IP).

• Current versions of IP include IPV4 and a newer version-IPV6.

9

BIT 1102: Communications Technology & the Internet

Brief History of the Internet

• 1958: Advanced Research Project Agency (ARPA) later known as DARPA is created in the United states.

• 1969: Development of Packet switching and the first packets are transmitted over a network named ARPANET.

• 1982/1983: Introduction of the TCP/IP protocol suite that enable communication between different networks.

•

10

BIT 1102: COMMUNICATION TECHNOLOGY AND THE INTERNET

Internet History continued

1983: First TCP wide Area Network known as the NFSNET was created by the National Foundation of Science (NFS) as a University backbone.

1989/1990: Due to the popularity of the TCP/IP, several other networks implemented it. Tim Bernes Lee at CERN creates first few www pages and develops the HTTP. The term Internet is introduced with over 100,000 internet hosts worldwide.

11

BIT 1102: COMMUNICATION TECHNOLOGY AND THE INTERNET

WORLD INTERNET USAGE AND POPULATION STATISTICS

March 31, 2011

Source: http://www.internetworldstats.com/stats.htm

WORLD REGIONS Population2011 estimate

Internet UsersDec. 31, 2000

Internet UsersLatest Data

AFRICA 1,037,524,058 4,514,400 118,609,620

ASIA 3,879,740,877 114,304,000 922,329,554

EUROPE 816,426,346 105,096,093 476,213,935

MIDDLE EAST 216,258,843 3,284,800 68,553,666

NORTH AMERICA 347,394,870 108,096,800 272,066,000

LATIN AMERICA/ CARIB

597,283,165 18,068,919 215,939,400

OCEANEA/AUSTRALIA

35,426,995 7,620,480 21,293,830

WORLD TOTAL 6,930,055,154 360,985,492 2,095,006,005

12

The World Wide Web:

The World wide web can be described as the huge amount of Information stored on the internet that can be accessed by users Worldwide.

It is referred to as the “web” because users move from one resource to another using the “hyper links”.

Tim Bernes Lee is the founder of the World Wide Web , HTTP, and HTML- Language that is a standard used to develop websites)

The World Wide Web consortium (w3.org) helps develop the web standards.

BIT 1102: Communications Technology & the Internet

13

Discussion:

How has the Internet and the worldwide Web affected us in the following aspects:

Education: Health: Economic Development: Socially / personally: Politically ETC

14

BIT 1102: COMMUNICATION TECHNOLOGY AND THE INTERNET

Intranet

• An Intranet can be defined as the private network that uses internet protocols like HTTP and FTP to securely share information in the internal environment such as an Organisation.

• To access the intranet, a user generally has to be authenticated / authorized through mechanisms such as login passwords.

• An example of an Intranet is the Students Results Management System at CoCIS which only allows CoCIS students to access their results from within the Institution.

BIT 1102: Communications Technology & the Internet

15

Intranet cont’d

Intranet can be described as the “mini internet” within an organisation that suites the internal needs of that organisation.

An extranet can be viewed as part of the intranet that is accessible to selected and authorised outsiders such as suppliers, Vendors etc. External Examiners of MUK can access needed information

BIT 1102: Communications Technology & the Internet

16

Why Intranets

They enable knowledge sharing and interactive Discussions.

Easy and speedy communication within an organisation

Enables distribution of confidential company sensitive information such as personnel records, operation manuals, work policies, strategies etc. (read more about Intranets)

17

BIT 1102: Communications Technology & the Internet

The Internet: How do we get access?

We have defined what the Internet is and the vast information stored the WWW,

Next we attempt to answer these questions.How does one get access to the internet?What access methods are available?What are the considerations to be made?

BIT 1102: COMMUNICATION TECHNOLOGY AND THE INTERNET

18

Internet Service Providers

• An ISP is an organisation that provides an individual or company with internet access and services usually at a monthly / annual fee.

• In Uganda, we have several ISPs such as– MTN– Uganda telecom– Bush net– Afsat– Infocom– Orange– Airtel– ETC

BIT 1102: COMMUNICATION TECHNOLOGY AND THE INTERNET

19

Some consideration

What service is being provided eg Broadband, Dail up Modem?

Speed: (Bandwidth is the amount of information that can be transferred across a network in a given time. Measured Bit/kiloBits /mega Bits per second).

Cost: (can the individual / organisation afford?)

Availability: eg some areas may not have a particular service perhaps due lack of infrastructure.

Internet services are discussed next

20

Dial-up Internet Access

Dial-up internet access involves the user connecting to the internet using a Modem over telephone lines.

Dial up modems have a theoretical speed of 56 KBPS but dial up internet transfer speeds will generally average between 33-45 KBPS due to data transmission and conversion delays (overhead).

After many years of usage, Dial-Up Internet is slowly being replaced by newer technologies such as the ISDN and Broadband

21

ISDN

ISDN (Integrated Services Digital Network ) is a network technology that supports digital transfer of simultaneous voice and data traffic. Similar to DSL in this respect, an ISDN Internet service works over ordinary telephone lines.

Supports data rates of 128 Kbps.

ISDN emerged as an alternative to traditional dialup networking during the 1990s. The much higher network speeds supported by newer broadband technologies like DSL have drawn many consumers away from ISDN service.

BIT 1102: COMMUNICATION TECHNOLOGY AND THE INTERNET

22

Broadband Internet

The most common type of Internet service is called broadband internet which is generally referred to as “High speed internet”.

Broadband generally refers to as an Internet connection with a speed of at least 200kb/s though this is not industry standard.

Broadband Technologies include : DSL (Digital Subscriber line ). This includes

ADSL and SDSL. Cable Internet Satellite internet

23

i) Digital subscriber Line x DSL

Using a DSL modem, DSL is a digital communications Technology that offers high speed internet services over plain old Telephone Service lines.How DSL works:

It works by utilising unused frequencies on the normal telephone line that was developed to cater for the human voice.

The modem converts digital signals into voltage of suitable frequency range

24

Synchronous Digital Subscriber Line (ADSL)

ADSL is one of the most popular DSL technologies in home and small office Internet connections. ADSL transmission rates generally vary from 512 KBPS to 8MBPS for upload and download speeds respectively.

The User needs to be located roughly 3 miles from the phone exchange company. (phone line restricts distance because of the high frequency transmissions).

25

Synchronous Digital Subscriber Line (ADSL) cont’d

“Asynchronous” as opposed to “Synchronous” DSL (SDSL) means that ADSL has lower upload than download speeds while SDSL has equal speeds.

SDSL requires more specialised equipment.

Other variations of DSL include HDSL, VDSL etc

BIT 1102: COMMUNICATION TECHNOLOGY AND THE INTERNET

26

Cable internet

Another popular Broadband Access method (about 22m users in US) that has high speeds.

This technology uses cable modem to provide internet services over the cable TV Infrastructure by utilizing the free bandwidth.

BIT 1102: COMMUNICATION TECHNOLOGY AND THE INTERNET

27

Other services

Other Internet access methods include Satellite Internet that provides internet Access via global satellite. This provides access where Land-based Infrastructure such as phone lines may not be available such as in war zones or other remote areas.

Broadband wireless internet technologies such as Wimax are being developed to provide the “last mile” connection between wired Broadband services such as DSL to wireless networks. Wimax is sometimes referred to as Wireless Metropolitan Network (wMAN)- read more

28

Read about the internet – its history and use and how

organizations connect to it.

BIT 1102: Communications Technology & the Internet

29