Recap of Lecture 1

Data CommunicationBrief History of Communication

Data Communication System

Key Data Communication Terminology

Networks and their need Distributed Processing Network CriteriaNetwork Applications

Today ‘s Topics

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- And their need:Point to point communication not usually practical

Devices are too far apartLarge set of devices would need impractical number of connections

Solution is to connect all devices to a central system known as a NETWORK

Two Main Classes of NetworksLocal Area Networks (LANs)Wide Area Network (WANs)

Networks- And their need:

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 basesFaster Problem SolvingSecurity through RedundancyCollaborative Processing

Network Criteria

Data Communication Network Criteria

Performance Reliability Security

Network CriteriaPerformance

Number of UsersType of Transmission Medium HardwareSoftware

Network CriteriaReliability

Recovery Time after Failure CatastropheFrequency of failure

Network CriteriaSecurity

Viruses Unauthorized Access

Network ApplicationsMarketing and SalesFinancial ServicesManufacturingElectronic MessagingTeleconferencingCable Television

SummaryKey Data Communication Terminology

Networks and Why we need Them?

Distributed Processing Network CriteriaNetwork Applications