DATA COMMUNICATION Lecture-2

Recap of Lecture 1 Data Communication Brief History of Communication Data Communication System

Overview of Lecture 2 Key Data Communication Terminology Networks and Why we need Them? Distributed Processing Network Criteria Network Applications

Key Data Communication Terminology Session: communication dialog between network users or applications Network: interconnected group of computers and communication devices Node: a network-attached device

Key Data Communication Terminology Link: connects adjacent nodes Path: end-to-end route within a network Circuit: the conduit over which data travels

Key Data Communication Terminology Packetizing: dividing messages into fixed-length packets prior to transmission over a network’s communication media Routing: determining a message’s path from sending to receiving nodes

Network A “Network” is a set of devices (Nodes) connected by Communication Links

Networks- Why we need Them? Point to point communication not usually practical Devices are too far apart Large set of devices would need impractical number of connections

Networks- Why we need Them? Solution is to connect all devices to a central system known as a NETWORK Two Main Classes of Networks Local Area Networks (LANs) Wide Area Network (WANs)

Distributed Processing “Instead of a single large machine being responsible for all aspects of a process, each separate computer handles a subset of the task”

Advantages of Distributed Processing Security Distributed Data bases Faster Problem Solving Security through Redundancy Collaborative Processing

Data Communication Network Criteria Performance Reliability Security

Network Criteria Performance Number of Users Type of Transmission Medium Hardware Software

Network Criteria Reliability Frequency of failure Recovery Time after Failure Catastrophe

Network Criteria Security Unauthorized Access Viruses

Network Applications Marketing and Sales Financial Services Manufacturing Electronic Messaging Teleconferencing Cable Television

Summary Key Data Communication Terminology Networks and Why we need Them? Distributed Processing Network Criteria Network Applications

Suggested Reading Section 1.3, “Data Communications and Networking” 2nd Edition by Behrouz A. Forouzan Sections 1.3, “Data and Computer Communication” 6th Edition by William Stallings