Chapter_1.pdf

11/13/2023 COMPUTER NETWORK CHAPTER ONE Asst. Prof. Rebwar Raees Sulaimani Polytechnic University Chamchamal Technical Institute IT Dept. CONTACT INFO E- mail: [email protected] 1 11/13/2023 BRAIN STORM Why do we need communications?  Why do we need computer networks?  Is there anythi...

11/13/2023 COMPUTER NETWORK CHAPTER ONE Asst. Prof. Rebwar Raees Sulaimani Polytechnic University Chamchamal Technical Institute IT Dept. CONTACT INFO E- mail: [email protected] 1 11/13/2023 BRAIN STORM Why do we need communications?  Why do we need computer networks?  Is there anything shared?  INTRODUCTION    Network is an interconnection between two or more devices that able to send or receive data. The purpose of a network is to enable the sharing of files and information (email, instant message, Voice, Vedio ……) Example The Internet could be described as a global network of networks. Mobile Communication system (ex: Asia cell) can be described as a wireless network 2 11/13/2023 INTRODUCTION  The Element of a Network are DEVICES  End-user Devices generates messages Ex: Cell phone, PC , IP phone & Security cameras . ( can be client or server), they have their own address 3 11/13/2023 DEVICES Intermediary Devices make possible to deliver data form source to destination Ex: Switch, Router, Firewalls. Mainly they are responsible for: 1. Regenerate and retransmit data signals 2. Determine the pathways exist through the network 3. Notify other devices of errors and communication failures  MEDIUM  Medium provides the channel over which the message travels from source to destination. 4 11/13/2023 MEDIUM Modern networks primarily use three types of media RULE & SERVICE Rules: are the standards and protocols that specify how the messages are sent, how they are directed through the network. Services include many of the common network applications like e-mail 5 11/13/2023 LAN, WAN & INTERNETWORKS Networks infrastructures can vary greatly in terms of: 1. The size of the area covered 2. The number of users connected 3. The number and types of services available LOCAL AREA NETWORK LAN: usually spans a single geographical area, providing services and applications to people within a common organizational structure, such as a single business, campus or region. 6 11/13/2023 WIDE AREA NETWORK Networks that connect LANs in geographically separated locations are referred to as Wide Area Networks (WANs) INTERNET--! Internet is created by the interconnection of networks belonging to Internet Service Providers (ISPs). These ISP networks connect to each other to provide access for millions of users all over the world 7 11/13/2023 INTRANET The term intranet is often used to refer to a private connection of LANs and WANs that belongs to an organization, and is designed to be accessible only by the organization's members, employees, or others with authorization. REVISION Elements of a network can be classified into …..  What are the differences between end-user device and intermediary device?  LAN refer to interconnection of several WANs, is that true ?  8 11/13/2023 NETWORK TERMINOLOGY Drawback Congestion Collision Remote Access Privacy Physical Logical Layer Encapsulation de capsulation 9