 Prof. Dr. M. H. Assal A.S. 1/4/2014

 A network is a collection of computers or other hardware devices that are connected together, using special hardware and software, to allow them to exchange information and cooperate. 2

 Sharing an Internet connection among several users.  Sharing application software, printers, and other resources.  Facilitating Voice over IP (VoIP), , video conferencing, messaging, and other communications applications.  Working collaboratively, such as sharing a company database.  Exchanging files among network users and over the Internet. 3

Networks can be identified by a variety of characteristics:  Wired or Wireless access  Topology  Architecture  Size or Coverage area 4

 Wired network: A network in which computers and other devices are connected to the network via physical cables.  Wired networks include: o Conventional Telephone Networks o Cable TV Networks  The wired networks commonly found in: o Schools o Businesses o Government Facilities 5

 Wireless network: A network in which computers and other devices are connected to the network without physical cables; data is typically sent via radio waves.  Wireless networks include: o Conventional television and radio networks o Cellular telephone networks, o Satellite TV networks  The wireless networks commonly found in: o Homes o Schools o Businesses 6

WiredWireless Advantages Inexpensive Equipment Extremely Reliable Superior Performance Greater Mobility Relatively Easy to Setup Much less cabling Disadvantages Need to run cables n difficult environments (walls, floors & ceilings) Cables needed for device to device communication Not very much Reliable Suitable for mobile devices only Slower than Wired 7

 Topology is how the devices in the network (called nodes) are arranged.  Bus networks: A network consisting of a central cable to which all network devices are attached 8

 Ring networks: Network devices are connected in a circular chain, with the channel beginning and ending at the same computer. 9

 Star networks: A network in which any device is connected directly to several other devices 10

 Mesh networks: A network in which there are multiple connections between the devices on the network so that messages can take any one of several paths.  Some networks use a combination of topologies 11

 Architecture is the way Networks are designed to communicate.  The two most common network architectures are: o Client-server o Peer-to-Peer (P2P). 12

 Client-Server Networks include both clients (computers and other devices on the network that request and utilize network resources) and servers (computers that are dedicated to processing client requests). 13

 With a peer-to-peer (P2P) network, a central server is not used. Instead, all the computers on the network work at the same functional level, and users have direct access to the computers and other devices attached to the network. 14

 Networks are classified is by the size of their coverage area. This also impacts the types of users the network is designed to service.  The most common categories of networks: o Personal Area Networks (PANs): A network that connects an individual’s personal devices that are located close together. o Local Area Networks (LANs): A network that connects devices located in a small geographical area, such as within a building. o Wide Area Networks (WANs): A network that connects devices located in a large geographical area. o Intranets: is a private network (such as a company LAN) that is designed to be used by employees and is set up similar to the Internet and is accessed via a Web browser. o A company network that is accessible to authorized outsiders is called an extranet. 15

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 Telephone Service  Global Positioning System (GPS) Applications  The Internet  Television and Radio Broadcasting  Monitoring Systems  Videoconferencing, Collaborative Computing  Telemedicine 17

18  The Internet o The Internet is the largest and most well-known computer network in the world. o It is technically a network of networks, since it consists of thousands of networks that can access each other via the internet backbone. o Many networking applications today (such as information retrieval, shopping, entertainment, and ) take place via the Internet.

 The Internet is a worldwide collection of separate, but interconnected, networks accessed daily by millions of people using a variety of devices to obtain information, access entertainment, or communicate with others. 19

 The Internet we know today is the result of the evolution of ARPANET and the creation of the World Wide Web (WWW).  ARPANET Project: o created by The U.S. Department of Defense Advanced Research Projects Agency (ARPA) in 1969 o small network of supercomputer o allow researchers located in different places to communicate with each other 20

 The World Wide Web: The collection of Web pages available through the Internet o Proposed by Tim Berners-Lee in 1989 o Originally only text-based Pages linked together through text or images (today’s hyperlinks) o Wide variety of content available via Web pages today (social networking, podcasts, blogs and wikis)  Internet2: Researches advanced Internet applications and technologies 21

 Most members of the Internet community fall into one or more of the following groups: o Users: People who use the Internet o Internet service providers (ISPs): Provide access to the Internet, typically for a fee o Internet content providers: Provide Internet content (Businesses, organizations, educational institutions, Individuals) o Application service providers (ASPs): Companies that manage and distribute software-based services over the Internet Web service: Added to a Web page to provide specific services for end users o Infrastructure companies: Own or operating the physical structure of the Internet (Conventional/Mobile phone companies, & satellite Internet providers) 22

 Possible devices include: o Personal Computers o Mobile Phones o Gaming devices  Connections can be: o Dial-up Uses standard phone lines & modem to dial-up ISP Inconvenient Slower, but cheaper Ties up telephone lines 23

o Direct (always on) Device is continually connected to the Internet typically broadband; fast speeds needed for many Web activities today Because you are always connected, it is important to protect your computer from hackers DSL: Broadband delivered over telephone lines Transmits over telephone lines but does not tie up the line Satellite: Broadband option for rural areas Requires satellite modem, and transceiver dish Fixed wireless: Uses radio transmission towers rather than satellites Mobile wireless: Access via mobile phone or device Hotspot: Public wireless networks (Wi-Fi) 24

 TCP/IP is a set of protocols developed to allow cooperating computers to share resources across a network  TCP stands for “Transmission Control Protocol”  IP stands for “Internet Protocol”  Every host on the Internet must have a unique IP address  The IP (version 4) or IPv4 address is a 32-bit number written in dotted 4 decimal parts.  Each part range from 0 to 255 (Single Byte).  A maximum of 4.3 billion possible addresses Ex:

 While 4.3 billion addresses might seem enough, The world run out of addresses by the end of  Because most every Computer, Smart Phone, Printer, Game Console, … require IP addresses, IPv4 was insufficient.  Good news ! a new internet addressing system has been rolled out, and it fills our need for more addresses. It called IPv6 or IP Version 6.  IPv6 uses 128 bits instead of 32 bits for its addresses, creating 3.4 x 10^38 possible addresses (a trillion-trillion- trillion) Ex: 21DA:D3:0:2F3B:2AA:FF:FE28:9C5A 3ffe:1900:4545:3:200:f8ff:fe21:67cf 26

 IP addresses are used to identify hosts on a TCP/IP network  Example:  Numbers are not ‘friendly’ – people prefer names  DNS is a protocol used to map IP addresses to textual names  e.g. maps to

 DNS names have a hierarchical structure  Example: 28 Top Level Domain (LTDs). com Microsoft netgoveg comedu mti appsintroeLearning… cuasu net… uk… Root Level 2 nd Level Domain Subdomains

 How a DNS query is resolved  When you type mti.edu.eg into your computer’s web browser i.e. Firefox, Chrome, IE, Spartan, … 1. Type mti.edu.eg in your Browser 2. Query DNS server for mti.edu.eg Root Server eg Server edu Server mti.edu.eg Open (connect)

 World Wide Web  is the most popular form of business communication-surpassing conventional mail  Instant Messaging (Chatting)  FTP: Protocol for copying files between client and an FTP server  E-commerce: Online financial transactions 30

 Social networking site: A site that enables a community of individuals to communicate and share information o Facebook, Twitter etc. allow people to post information about themselves o Video and photo sharing (YouTube, Flickr, etc.) o Used in politics and business (LinkedIn, etc.)  Users should be careful not to reveal too much about themselves for safety reasons 31

 Netiquette is a set of rules for properly behaving online. These rules are intended to enhance the quality of discussion.  Adhere to the same standards of behaviors online that you follow in real life.  Treat that you receive as confidential unless the sender specifically gives you permission to share it with others.  Respect the copyright and license agreements of material written by others. If you quote something from a book or magazine, mention your source.  Typing messages in all caps is as bad as shouting  Do not assume any Internet communication to be completely secure  Use abbreviations sparingly; overuse can make your message difficult to understand. 32

 Myth 1: The Internet is free o Most people and businesses pay for Internet access o Businesses & schools lease internet lines from phone companies o Fee-based content is growing at a rapid pace Music/movie downloads Donation based sites  Myth 2: Someone controls the Internet o No single group or organization controls the Internet o Governments can regulate Internet use within its country, but difficult to enforce  Myth 3: The Internet and World Wide Web are identical o Internet = physical network o WWW = one resource (Web pages) available via the Internet 33

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