World Famous Networks

• There are so many large and specific networks in the world that performs specific operations. Some of them are public and some are private networks. Among these, it may be research networks, cooperative networks, commercial or corporate networks, etc.
• These large networks can be distinguished from each other on the basis of their history, administration, facilities/services, offered, technical design, and the people who use them (user communities) etc.
• There are some unique or specific typical world-famous computer networks are –

[A] ARPANET

[B] INTERNET

[C] NOVELL NETWARE

[D] ATM NETWORK

[A] ARPANET

• ARPANET was established in 1969 by the Advanced Research Projects Agency (ARPA) of the US Department of Defense.
• Bob Taylor initiated the ARPANET project in 1966 to enable access to remote computers. ARPANET was an American military defense agency that was established in 1969 and by 1990 the ARPANET was shut down and dismantled.
• In 1969, the American Department of Defense (DOD) started a network of devices called ARPANET (Advanced Research Projects Administration Network) with one computer in California and three in Utah. In September 1969, the University of California at Los Angeles (UCLA), the Stanford Research Institute (SRI), the University of California, Santa Barbara (USCB), and the University of Utah were connected by a network that was called the ARPANET.
• The ARPANET(Advanced Research Projects Agency Network) was the first wide-area packet-switched network with distributed control and one of the first working computer networks to implement the TCP/IP protocol suite.
• Its initial purpose was to link computers at Pentagon-funded research institutions over telephone lines but later mainly used in academic and research work.
• This WAN network finally leads to today’s Internet later time, hence ARPANET is popularly called the ‘Pioneer of Internet’.

[B] INTERNET

History of Internet

• The Internet was not developed within a period of a few days or a few months. Rather, it is the result of long and aggressive research that took many years.
• The term Internet was finally coined in 1995 by the FNC (Federal Networking Council, USA).
• The internet’s evolution can be broadly categorized into several phases:
  1. Pre-Internet era(1960s):
     • The foundation for the Internet was laid with the development and use of early computer networks.
     • Research organizations like RAND(Research and Development) Corporation and ARPA (Advanced Research Projects Agency) worked on projects that led to the creation of packet-switching networks, which formed the basis for data transmission in the future internet.
  2. ARPANET and Early Networks (1969-1980s):
     • ARPANET, initiated by the U.S. Department of Defense’s ARPA, is often considered the precursor to the modern internet.
     • It successfully connected various research institutions, allowing researchers to share resources and communicate electronically.
     • The development of protocols like TCP/IP (Transmission Control Protocol/Internet Protocol) standardized data transmission, paying the way for interoperability between different networks.
  3. Commercialization and World Wide Web (1990s):
     • The 1990s witnessed the commercialization of the Internet and the emergence of the World Wide Web. Tim Berners-Lee’s invention of the WWW allowed users to easily navigate and access content using hyperlinks.
     • This period also saw the proliferation of internet service providers (ISPs) and the growth of e-commerce, online communities, and search engines.
  4. Dot-com Bubble and Broadband Expansion (Late 1990s – Early 2000s):
     • The late 1990s saw the dot-com bubble, characterized by a rapid rise in internet-based companies and investments. While the bubble eventually burst, it led to advancements in internet infrastructure and broadband technology, enabling faster and more reliable connections for users.
  5. Web 2.0 and Social Media (The mid-2000s):
     • The mid-2000s marked the transition to Web 2.0, characterized by interactive and user-generated content. Platforms like Facebook, YouTube, and Twitter gained prominence, reshaping how people share information and connect online.
     • Mobile internet access also became more prevalent, leading to the development of mobile apps and responsive web design.
  6. Cloud Computing and Internet of Things (2010s):
     • Cloud computing revolutionized how services and resources are accessed and delivered over the internet.
     • This decade also saw the rise of the Internet of Things (IoT), where everyday objects are connected to the Internet, enabling data exchange and automation on a large scale.
  7. 5G and Future Developments (2020s and Beyond):
     • The ongoing development of 5G networks promises even faster and more reliable connectivity, supporting applications like augmented reality, autonomous vehicles, and advanced IoT deployments.
     • Additionally, concerns about privacy, cybersecurity, and digital inclusion have become central issues in the continued evolution of the Internet.

Introduction of Internet

• The Internet is evolving every day and it is difficult to visualize or describe each and every aspect of the architecture of the Internet.
• The process of interconnection between two/more different networks is called internetworking.
• The Internet is often referred to as the ‘Net’.

Definition of Internet

• The internet is comprised of several same and different types of networks, connected with each other either with the same or different protocols.
• The Internet is the largest, global, WAN type of network of computers and their related and associated devices.

Features of Internet

• The best example of internetworking is the internet.
• The Internet is often called the ‘Network of Networks’.
• It allows easy and quick access to a huge amount of information/resources stored at many different locations around the world.

Functioning/Working Mechanism of Internet

• The functioning of the Internet is not controlled/governed by a single/one particular organization. Rather, it is managed by a group of voluntary organizations called the Internet Society. They decide the rules/protocols, for communication over the Internet.
• The different networks may have their own rules that they follow internally, but when they communicate with each other, they must follow some common rules of the internet. 
• In order to activate Internet services on any computer, it requires an Internet connection from an Internet Service Provider. There are several Internet Service Providers (ISPs) in India like VSNL, BSNL, Airtel, Reliance, etc. They charge a nominal fee for installation and connection. Depending on the requirement we can get any one type of Internet access method or connection.
• In order to have an internet connection we need a device called the modem. which converts the digital signal from the computer into an analog signal that can travel through the telephone line. On the other end, this analog signal is again converted back to digital form by the modem at the destination end of the computer. Some computer systems have internal modems (built-in within the motherboard) while in some systems there might be a need to have an external modem(outside the system) to have an Internet connection. Another device called a router can be attached to the computer to access the Internet. The router is a device used for connecting two different networks.

Architecture of Internet

• It consists of a complex network of computers connected by high-speed communication technologies like satellites, microwave devices, etc.

Uses/Applications of the Internet

There are the following common use of the Internet normally seen – 

(a) Search the Information :

• As we know that Internet is a sea of information and hence user searches all these using certain keywords with the help of search engine.

(b) E-mail Services :

• E-mail is the commonly used service over the internet for sending and receiving e-mails. We can send a message electronically to any person on the globe, provided that person has an e-mail-id. This service is fast and economical.

(c) Chatting Services :

• Chatting services are the textual exchange of messages in real-time.
• In chatting, chat servers provide the facility to create virtual chat rooms, and only the members associated with these rooms are allowed to share their messages.
• Chat works best when the time is scheduled by both parties who are willing to chat – as both parties must be connected to the Internet while chatting.
• Some common chat engines are Yahoo Messenger, Google Talk, Rediff Bol, etc.

(d) Instant Messanger Services :

• These tools are used to send messages instantly.
• It also allows us to talk to anyone anywhere in the world.
• This is a cheaper and quicker method compared to other services.
• Unlike chatting, it is not necessary to have an account with the same provider. Additionally, both users need not be connected while sending messages.
• We can easily download messenger software from the Internet e.g. MSN Messenger, Yahoo Messenger, etc.

(e) Newsgroup Services :

• The newsgroup is an e-service hosted by many newsgroup organizations. One can become a member of a newsgroup and read and share current affairs and messages.
• Newsgroups cover a broad domain of interests including education, science and technology, medicine, arts, sports, etc.
• USENET is a popular example of a newsgroup.

(f) Teleconferencing Services :

• In Teleconferencing, people can have a conference or meeting sitting at different locations with a microphone attached to their computers/smartphones.
• In teleconferencing, we are able to only talk to each other sitting at different places.

(g) Video Conferencing Services :

• In video conferencing, we can talk and see what is happening on the other side simultaneously. We have observed that the anchor, panelists, and experts sitting at different locations across the globe communicate and share their views in many news channels. For this, we need a web camera and a microphone connected to the computer system or smartphone, high bandwidth connection, and video-conferencing software.

• outside even in diverse conditions such as heat or heavy rains. He can do shopping by sitting at home, visiting the desired e-commerce site online and placing an order and then finally product is delivered to the destination address.

(h) M-Commerce Services :

• M-commerce stands for mobile commerce.
• It is an upcoming and even used modern technology after e-commerce.
• It involves buying and selling goods and services electronically through wireless handheld mobile devices at any place.
• We can do transactions through our mobile phones also.

(i) E-Services :

(a) E-Commerce

• • E-commerce(Electronic-Commerce) means online transactions of a business.
  • In this, the vendor and customer conduct a transaction sitting at different geographical locations, connected through the Internet.
  • In this, the customer need not strain himself by visiting a number of shops outside even in diverse conditions such as heat or heavy rains. He can do shopping by sitting at home, visiting the desired e-commerce site online and placing an order and then finally product is delivered to the destination address.

(b) E-Banking

• • In E-Banking, almost all the nationalized banks have started providing their services/transactions online through the Internet.
  • E-banking is a facility that allows us to conduct our banking transactions online with a laptop or computer with an Internet connection. For this, every user is allotted a unique user id and password by the bank for this purpose. The account holder can view account balances and transaction statements, transfer money between accounts in the bank, pay utility bills at any time of the day and from any place, can take printouts of financial statements, and many more.

(c) E-Learning

• • E-learning is educating people online with the help of the Internet.
  • Development in this field has led to the formation of virtual classes and online sessions. Here, a teacher can teach many students at the same time sitting at different geographical locations. Such classes may be open to all or may require prior student registration.
  • E-Learning can be delivered in different ways:
    [i] At the time of learning teachers and students both are to be online.

Video Lecture: The teacher or instructor can take a class while students can see and listen to him/her. For such a classroom a web camera is required at every terminal.
Textual Lecture: The teacher can take a class by passing his lectures as text and students providing textual responses. Students can post their queries online and can get a response instantly.

[ii] At the time of class both teacher and student need not be online at the same time.

(a) The teacher can send the lecture using tools like explaining these and blogs online to the students.
(b) The students can read their lessons online. If they have any queries then they can mail their queries to the teacher’s account.

[C] NOVELL NETWARE

History :

• There are several versions of NetWare.
  • The earlier versions of NetWare 286 version 2. X was written to run on 286 machines.
  • NetWare 386 versions 3. X was written to run on 386 and 486 machines.
  • The most recent version is NetWare 4. X can probably run on almost any type of machine.
  • The latest version of Netware is 6.5

Introduction :

• The official website of this system is http://www.novell.com.
• NetWare evolved from a very simple concept: file sharing instead of disk sharing.

Definition :

• Novell is a company and Netware is a widely installed network server operating system made by Novell itself in 1983. Thus, Novell NetWare is the most popular network system in the PC world.

Characteristics :

• This network OS works in CUI(Command line User Interface or Character User Interface or Text User Interface) mode like MS-DOS.
• This network operating system is used as a multitasking OS to run various services on a PC.
• Netware OS is hardware-independent, running on any suitable Intel-based IBM PC  compatible and a wide range of network cards.
• Netware OS also works in/supports heterogeneous networks.
• Netware OS needs only low hardware requirements and has memory protection.
• This system is specially made for LAN environment and its product runs on a variety of different types of LAN.

Architecture :

• Novell Networks system works on the principle of the client-server model in which at least one computer functions as a Server which is actually called here Network File Server, which actually runs all of the NetWare protocols and maintains the network’s shared data on one or more disk drives.
• Here, network file servers/servers generally allow users on other PCs to access application software or data files i.e., it provides services to other network computers called clients.
• There are two types of file servers found in this system :
  • Dedicated file servers.
  • Non-dedicated file servers.

Dedicated File Servers:

• • The dedicated file server runs only NetWare and does not run any other software, such as Windows applications.
  • Dedicated file servers are mostly used in large networks, because, in large networks, one extra client is less significant and a dedicated server can handle a larger number of requests more efficiently. In large networks, security is one of the major concerns, and providing a clear distinction between client and server hardware provides greater security. 

Non-dedicated File Server:

• • A non-dedicated file server can run both applications and NetWare.
  • It is useful in small networks because it allows the server to also act as a client and thus, increase the number of clients in the network by one.
  • There are many other servers within a Novell NetWare such as Print server, Message server, Database server, etc.
    
    Print server: The job of the Print server is to allow users to access shared printers. A Print server manages both requests and printers.
    
    Message server: The job of the Message server is to transfer email messages between a client’s PC and a user’s mailbox.
    
    Database server: A database server manages database files i.e., it adds, deletes, and modifies records in the database; queries the database and generates the result required by the client; and transmits the results back to the client.

• Novell Netware System uses IPX (Internet Packet eXchange) network protocol in place of TCP/IP in its proper network functioning. This model is based on the old Xerox Network System, XNS™ but with a lot of modifications. 
• The IPX protocol stack consists of 4 layers –
  • Physical & Data Link Layer
  • Network Layer
  • Transport Layer
  • Application Layer

(Here, the Session and Presentation Layer do not exist.)

• • Physical & Data Link Layer
    • The Physical and Data link layers contain the Ethernet, IBM Token ring, and ARCnet protocols.
  • The Network Layer
    
    • The Network layer has a protocol called IPX(Internet Packet eXchange) that creates an unreliable connectionless between source and destination even on different networks.
    • The functioning of IPX is similar to IP of TCP/IP, except that IPX uses 12-byte addresses instead of 4-byte addresses of IP.

• • The Transport Layer
    
    • The Transport layer contains a protocol called NCP (Network Core Protocol) that creates a reliable connection(connection-oriented) between the source and destination.
    • NCP is believed that the heart protocol of NetWare and provides various other services besides user data transport i.e. it defines the type of requests that can be made and how the server responds to the request it eventually receives.
    • The other protocol of the transport layer is SPX (Sequenced Packet eXchange), which provides only transport.
  • The Application Layer
    
    • The Application layer contains various application protocols like SAP(Session Announcement Protocol), File servers, etc. 

Use :

• Installing its products in large as well as small office LANs is very successful.

[D] ATM NETWORK

History :

• ATM was developed in the late 1980s.

Introduction :

• ATM stands for ‘Asynchronous Transfer Mode’.
• ATM was developed to meet the needs of the Broadband Integrated Services Digital Network, and designed to integrate telecommunication networks.

Definition :

• ATM is a modern high-performance switching(both circuit and packet) & multiplexing(asynchronous TDM) network technology used in the telecommunication sector to transmit multimedia data(Video, Audio, Images, Text, etc.) with very high speed over the same network in the form of cells or packets of fixed size(53 bytes).
• ATM is a telecommunications standard defined by ANSI(American National Standards Institute) and ITU(International Telecommunication Union) (formerly called CCITT[Consultative Committee for International Telephony and Telegraphy]) for digital transmission of multiple data traffic, such as telephony (voice), data, images, and video signals in one network without the use of separate overlay networks.

Characteristics :

• ATM technology may be used in LANs, MANs, and WANs.
• It supports real-time voice and video as well as data.
• Its topology uses a logical virtual circuit between source and destination, to transfer data reliably and hence maintain guarantees of quality of service (QoS) for data.
• They provide connection-oriented services using virtual circuits by packet switching technique.
• ATM is defined at the physical layer (Layer 1) and data link layer (Layer 2) of the OSI reference model.
• ATM is highly scalable.
• It supports various data transmission speeds of 1.5, 25, 100, 155, 622, 2488, and 9953 Mbps i.e. it can provide very high bandwidth with few delays.
• ATM is also running as slow as 9.6 Kbps between ships at sea. 

Architecture :

• Instead of using frames as in Ethernet, the ATM technique uses 53-byte, fixed-size cells.

Function :

•  It provides the following
  levels of service:
  􀁸 Constant Bit Rate (CBR) guarantees bandwidth for real-time voice and video.
  
  􀁸 Realtime Variable Bit Rate (rt-VBR) supports interactive multimedia that
  requires minimal delays.
  
  􀁸 Non-realtime variable bit rate (not-VBR) is used for bursty transaction traffic.

Available Bit Rate (ABR) adjusts bandwidth according to congestion levels for
LAN traffic.

􀁸 Unspecified Bit Rate (UBR) provides the best effort for non-critical data such
as file transfers.

Advantages of ATM : 

• Provides flexible bandwidth allocation.
• Uses a simple routing algorithm due to connection-oriented services.
• High bandwidth utilization during transmission due to the use of statistical multiplexing technology.
• Maintains guaranteed QOS (Quality Of Service) data delivery.
  
  

Disadvantage of ATM :

• The overhead of 5 bytes cell header per cell.
• Complex processing mechanisms for achieving Quality of Service.
• Congestion during data transmission may cause cell losses.
• It is costly compared to the IP mechanism.

Use :

• ATM is now used as a core protocol in the SONET/SDH(Synchronous optical networking/synchronous digital hierarchy)backbone of the public switched telephone network (PSTN) and in the Integrated Services Digital Network (ISDN).