Network, Internet and e-commerce Session 4

IS Infrastructure Components: Networking Both human and computer communication involve senders, a message to share, and receivers. Network requires: Sender and receiver Transmission pathway Rules/protocols for communication

Network and Telecommunications Two or more interconnected computers or computing devices. Telecommunications: transmittal of data and information Allows communications over large distances Network technologies bring about several improvements to business process The exchange of information in any form over a network

Networking and Communication Trends Convergence: Telephone networks and computer networks converging into single digital network using Internet standards Broadband: More than 68% U.S. Internet users have broadband access Broadband wireless: Voice, data communication are increasingly taking place over broadband wireless platforms

Networking and Communication Trends…… Examples of these trends in organizations? Why do managers need to be aware of these trends?

Communication Model

Transmission Modes Simplex Half duplex Full duplex One direction e.g. Television Half duplex Either direction, but only one way at a time e.g. police radio Full duplex Both directions at the same time e.g. telephone

What is a computer network? Two or more connected computers Major components in simple network Client computer Server computer Network interfaces (NICs) Connection medium Network operating system Hub or switch Router

Network Classification: Servers, Clients, and Peers Host (serve up) data, databases, files, applications, Web sites, video, and other content for access over the network Clients Consume hosted resources Peers (P2P) Serve and consume resources, both a server and a client interacting with similar computers

Client/Server network Nodes and servers share data roles Nodes are called clients Servers are used to control access Database software Access to data controlled by server Server is the most important computer

Peer to peer networks (P2PN) All nodes are equal Nodes access resources on other nodes Each node controls its own resources Most modern OS allow P2PN Distributed computing is a form Kazaa Torrent

Networking Hardware Networks use variety of devices to connect computers and peripheral devices Network interface card: connects through cable or wireless antenna to middle device Middle device connects to LAN or WAN Hub: central location to connect computers Switch: controls direction of communications Router: Connects Two or more network

Networking Hardware (continued) Bridge: connects two networks Router: routes data packets to next node Repeater: amplifies or regenerates signals Modem: translates communication signals form analog to digital and vice versa Dial-up connection: slower type of connection through modem

COMPONENTS OF A SIMPLE COMPUTER NETWORK Illustrated here is a very simple computer network, consisting of computers, a network operating system residing on a dedicated server computer, cable (wiring) connecting the devices, network interface cards (NICs), switches, and a router.

CORPORATE NETWORK INFRASTRUCTURE Today’s corporate network infrastructure is a collection of many different networks from the public switched telephone network, to the Internet, to corporate local area networks linking workgroups, departments, or office floors.

IS Infrastructure Components: Types of Computer Networks Usage Size Personal area network (PAN) Wireless communication between devices (Bluetooth) Under 10 meters Local area network (LAN) Sharing of data, software applications, and other resources between several users Typically a building Wide area network (WAN) Connect multiple LANs, distributed ownership and management Large physical distance, up to worldwide Networks are typically used to connect devices within an organization, or across organizational subunits. Increasingly, LANs are becoming wireless (WLANs) using high-frequency radio-wave technology; WLANs are also referred to as Wi-Fi networks (wireless fidelity). These are easier to install, as there is no need for cabling. Wide area networks can range from spanning multiple buildings (sometimes called a campus area network) to covering the area of a city (sometimes called a metropolitan area network) to worldwide (the Internet).

Network Topology Logical layout of wires and equipment Choice affects Network performance Network size Network collision detection

BUS Also called linear bus One wire connects all nodes Terminator ends the wires Advantages Easy to setup Small amount of wire Disadvantages Slow Easy to crash

STAR All nodes connect to a hub Packets sent to hub Hub sends packet to destination Advantages Easy to setup One cable can not crash network Disadvantages One hub crashing downs entire network Uses lots of cable Most common topology

RING Nodes connected in a circle Tokens used to transmit data Nodes must wait for token to send Advantages Time to send data is known No data collisions Disadvantages Slow Lots of cable

MESH All computers connected together Internet is a mesh network Advantage Data will always be delivered Disadvantages Lots of cable Hard to setup

TREE Hierarchal Model Advantages Scaleable Easy Implementation Easy Troubleshooting

Network Media Links that connect nodes Choice impacts Speed Security Size

Twisted-pair cabling Most common LAN cable Called Cat5, Cat 6 or 100BaseT Four pairs of copper cable twisted May be shielded from interference Speeds range from 1 Mbps to 10,000 Mbps

Coaxial cable Similar to cable TV wire One wire runs through cable Shielded from interference Speeds up to 10 Mbps Nearly obsolete

Fiber-optic cable Data is transmitted with light pulses Glass strand instead of cable Immune to interference Very secure Hard to work with Speeds up to 100 Gbps

Wireless Media Data transmitted through the air LANs use radio waves WANs use microwave signals Easy to setup Difficult to secure

Wireless Local Area Network LAN using wireless technology to connect computers or workstations Located within range of network Security vulnerabilities Open architecture; difficulty keeping intruders out

What is the Internet? A world-wide network of computers allows people to share information electronically Like a BIG book with many web-pages on different topics Can be accessed anywhere with an Internet connection

How you access to Internet ? A company that provides Internet access for customers (examples: World link , Mercantile , NTC ) Your computer connects to the Internet Service Provider (ISP), then to the Internet Your computer ISP Internet

The Internet and the World Wide Web (WWW) The Internet is one of several global networks The Internet has standard protocols The Internet is based on internetworking, or combining networks to form larger networks The World Wide Web uses the Internet The World Wide Web is not the Internet The World Wide Web is Web protocols (e.g., HTML and HTTP) Web pages (documents containing HTML ) Web servers (store and provide access to Web pages via a Web site) Web browsers (provide users with an interface to Web pages)

The Internet and the World Wide Web: Web Domain Names and Addresses Uniform Resource Locator (URL) is used to identify and locate a particular Web page Domain name is a term that helps people recognize the company or person Prefix, like “google” or “microsoft” Suffix, like .com, .edu, .org, .gov, or two-letter country codes Dissecting a URL.

The Internet and the World Wide Web: IP Addresses The Internet uses IP addresses IPV4: Old style, 32-bit, running out of addresses IPV6: New style, 128-bit, huge address space The WWW translates domain names into IP addresses www.kusom.edu.np translates to (IPV4) 209.190.97.210 A URL could be expressed directly as an IP address, although it’s more common to use domain name. The Internet uses a numeric addressing approach computers can understand. The old style of address was IPv4, which is running out of addresses and is slowly being replaced by IPv6, which has many more possible addresses and would allow for assigning a unique address to every grain of sand in the world. The World Wide Web uses domain names as an addressing technique, and then translates requests for domain names into the IP addresses. In addition to specifying the address of the Web server, URLs typically also include the path to the requested resource, such as a particular page located in a particular directory (e.g., http://mis.eller.arizona.edu/faculty/index.asp).

The Internet and the World Wide Web: World Wide Web Architecture Components Interconnected Web servers Utilize Transmission Control Protocol/Internet Protocol (TCP/IP) Communicate over the Internet Clients request Web page hosted on server Server breaks into packets Packets stream over internet to client Client reassembles Client can request retransmission of any missing packets Web browser translates Web page into visible output PACKED SWITCHED NETWORKS

Packet switching Method of slicing digital messages into parcels (packets), sending packets along different communication paths as they become available, and then reassembling packets at destination Previous circuit-switched networks required assembly of complete point-to-point circuit Packet switching more efficient use of network’s communications capacity

PACKED-SWITCHED NETWORKS AND PACKET COMMUNICATIONS Data are grouped into small packets, which are transmitted independently over various communications channels and reassembled at their final destination.

Switching technique Circuit switching: dedicated channel established for duration of transmission Packet switching: message broken into packets Packet: group of bits transmitted together Frame relay: high-speed packet-switching protocol used in WANs Variable-sized packets routed quickly

Circuit Switched Technology Connection is established between 2 devices on a network before they begin transmitting Bandwidth is dedicated to this connection and remains available only to the source and destination devices until the connection is terminated During connection all data follows the same path 1st selected by the switch or other connectivity device

Circuit Establishment

The Internet and the World Wide Web: Extranets and Intranets Companies have confidential data These data still need to be shared on a limited basis Intranet: password-protected Web site designed for sharing within the company Extranet: password-protected Web site designed for sharing with select partners Data and communication are protected via firewalls and virtual private networks (VPNs) Companies that want to share private data using the Internet create intranets for internal use and extranets for use by themselves and partner organizations. These protected Web sites allow wide sharing but with security to ensure data only reach the intended audience.

The Internet and the World Wide Web: Extranets and Intranets Intranet architecture Extranet architecture

Virtual Private Network using the Internet Why do organizations use VPNs? When is using a VPN a good idea? Laudon & Laudon, fig. 7-14 This VPN is a private network of computers linked using a secure “tunnel” connection over the Internet. It protects data transmitted over the public Internet by encoding the data and “wrapping” them within the Internet Protocol (IP). By adding a wrapper around a network message to hide its content, organizations can create a private connection that travels through the public Internet.

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