INTRODUCTION TO COMPUTER NETWORKS Dr Kusay Faisal Abdulrazak

INTRODUCTION TO COMPUTER NETWORKS Dr. Kusay Faisal Abdulrazak

The questions 1. 2. 3. 4. 5. 6. 7. What is network? Why do we need networking? How Data flow ? What are networks hardware components? How many types of network connection? How many kinds of Networks? How many network topologies?

What is a Network? A network is two or more computers linked together, it share data files, software applications and hardware like printer and other computer resources such as fax. Why do we need Networking? • Sharing information • Sharing hardware or software. • Centralize administration and support. 3

Data flow (simplex, half-duplex, and full-duplex) Simplex : one way like radio broadcast, Paging system satellite broadcasting. Half-duplex: two-way of communication Like: walky-talky, Full: like cellular system, Telephone.

Physical Structures � • Type of Connection – Point to Point - single transmitter and receiver – Point to Multipoint - multiple recipients of single transmission

How many kinds of Networks? • we can classify networks in different ways: • • Based on network size: LAN and WAN (and MAN) Based on management method: Peer-to-peer and Client/Server Based on topology (connectivity): Bus, Star, Ring. . Based on transmission media: Wired (UTP, coaxial cables, fiberoptic cables) and Wireless : : 6

LAN and WAN • Local Area Network (LAN) • Small network, short distance • A room, a floor, a building • Limited by number of computers and distance covered • Serve a department within an organization • Examples: • Network inside the Student Computer Room • Network inside your home 7

Figure. An isolated LAN connecting 12 computers to a hub in a closet

• Wide Area Network (WAN) • A network that uses long-range telecommunication links to connect 2 or more LANs/computers housed in different places far apart. • Towns, states, countries Your home • Examples: Internet WAN USA Student Computer Centre 9

WANs: a switched WAN and a point-to-point WAN

How many network topologies? � • There are four network topologies 1. Ring network If a cable breaks or one computer fails, whole network will fail. 2. Bus network If main cable fails, whole network will fail. 3. Star network If center server fails, whole network will fail. 4. Mesh network If a cable breaks or one computer fails, it won’t affect the other computers.