3_lecture_Networks (1).pptx

HINF232-TELEMEDICINE AND E-HEALTH Networks Computer Networks • Computer network connects two or more autonomous computers. • The computers can be geographically located anywhere. 2 LAN, MAN & WAN • Network in small geographical Area (Room, Building or a Campus) is called LAN (Local Area Networ...

HINF232-TELEMEDICINE AND E-HEALTH Networks Computer Networks • Computer network connects two or more autonomous computers. • The computers can be geographically located anywhere. 2 LAN, MAN & WAN • Network in small geographical Area (Room, Building or a Campus) is called LAN (Local Area Network) • Network spread geographically (Country or across Globe) is called WAN (Wide Area Network) 3 Applications of Networks • Resource Sharing  Hardware (computing resources, disks, printers)  Software (application software) • Information Sharing  Easy accessibility from anywhere (files, databases)  Search Capability (WWW) • Communication  Email  Message broadcast • Remote computing 4 Network Topology • The network topology defines the way in which computers, printers, and other devices are connected. A network topology describes the layout of the wire and devices as 5 Bus Topology • Commonly referred to as a linear bus, all the devices on a bus topology are connected by one single cable. 6 Star & Tree Topology • The star topology is the most commonly used architecture in Ethernet LANs. • When installed, the star topology resembles spokes in a bicycle wheel. 7 Ring Topology • A frame travels around the ring, stopping at each node. If a node wants to transmit data, it adds the data as well as the destination address to the frame. 8 Mesh Topology • The mesh topology connects all devices (nodes) to each other for redundancy and fault tolerance. • It is used in WANs to interconnect LANs and for mission critical networks like those used by banks and financial institutions. • Implementing the mesh topology is expensive and difficult. 9 Network Components • • • • • Physical Media Interconnecting Devices Computers Networking Software Applications 10 Networking Devices HUB, Switches, Routers, Wireless Access Points, Modems etc. 11 mputers: Clients and Servers In a client/server network arrangement, network services are located in a dedicated computer whose only function is to respond to the requests of clients. The server contains the file, print, application, security, and other services in a central 12 computer that is continuously available to