Introduction to Computer Networks Computer Networks Computer network connects two or more autonomous computers. The computers can be geographically located anywhere.
Introduction to Computer Networks LAN, MAN & WAN Network in small geographical Area (Room, Building or a Campus) is called LAN (Local Area Network) Network in a City is call MAN (Metropolitan Area Network) Network spread geographically (Country or across Globe) is called WAN (Wide Area Network)
Introduction to Computer Networks Applications of Networks Resource Sharing Hardware (computing resources, disks, printers) i Software (application software) Information Sharing i Easy accessibility from anywhere (files, databases) t Search Capability (WWW) Communication I Email y Message broadcast Remote computing Distributed processing (GRID Computing)
Local Area Networks (LANs)Local Area Networks are privately-owned networks within a small area,usually a single building or campus of up to a few kilometers.Since it is restricted in size, that means their data transmission time canbe known in advance, and the network management would be easier.Spring 2005 Local Area Networks 5
Motivations forLocal Area NetworkingThe growing demand for local area networks is due to technical,economic and organizational factors: Cost reductions through sharing of information and databases, resources and network services. Increased information exchange between different departments in an organization, or between individuals. The trend to automate communication and manufacturing process. Improve the community security. Increasing number and variety of intelligent data terminals, PCs and workstations.Spring 2005 Local Area Networks 6
Introduction to Computer Networks 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 well as the paths used by data transmissions.
Metropolitan area network• A Metropolitan Area Network (MAN) is a network that is utilized across multiple buildings• Commonly used in school campuses or large companies with multiple buildings• Is larger than a LAN, but smaller than a WAN• Is also used to mean the interconnection of several LANs by bridging them together. This sort of network is also referred to as a campus network 11
Metropolitan Area Networks (MANs)• A Metropolitan Area Network is a system of LANs connected throughout a city or metropolitan area. MANs have the requirement of using telecommunication media such as voice channels or data channels.• Branch offices are connected to head offices through MANs. Examples of organizations that use MANs are universities and colleges, grocery chains, and banks.
Wide Area Networks (WANS)WANs connect LANs together between cities
Wide Area Networks (WANS) …The main difference between a MANand a WAN is that the WAN uses LongDistance Carriers. Otherwise the sameprotocols and equipment are used as aMAN.
Wide area network• A Wide Area Network is a network spanning a large geographical area of around several hundred miles to across the globe• May be privately owned or leased• Also called “enterprise networks” if they are privately owned by a large company• It can be leased through one or several carriers (ISPs-Internet Service Providers) such as AT&T, Sprint, Cable and Wireless• Can be connected through cable, fiber or satellite• Is typically slower and less reliable than a LAN• Services include internet, frame relay, ATM (Asynchronous Transfer Mode) 17
Network Interconnection Components• Networks can be connected to each other through several components – Repeater – Bridge – Router 18
Repeater• Regenerates and propagates all electrical transmissions between 2 or more LAN segments• Allows extension of a network beyond physical length limitations• Layer 1 of the “OSI model”Network A Network B Higher Higher Layers Layers Repeater Physical Physical Physical 19
Bridge • Connects 2 or more LAN segments and uses data link layer addresses (e.g.MAC addresses) to make data forwarding decisions • Copies frames from one network to the other • Layer 2 of the “OSI model”Node in Network A Node in Network B Higher Higher Layers Bridge Layers Data Link Data Link 23-01-88-A8-77-45 Data Link Data Link 53-F1-A4-AB-67-4F Physical Physical 1 Physical 2 Physical 20
Router • Connects 2 or more networks and uses network layer addresses (like IP address) to make data forwarding decisions • Layer 3 of the “OSI model”A node in Network A A node in Network B Higher Higher Layers Router Layers Network Network 184.108.40.206 220.127.116.11 Network Network Data Link Data Link Data Link Data Link Physical Physical 1 Physical 2 Physical 21