Data Communication (CS601) Short Notes

Introduction to Data Communication

·       Communication: Sharing of Information (Local or remote)

·       Telecommunications: Communication at a Distance (includes telephony, telegraph, and television etc.)

·       Data communications: Exchange of data between two devices via some form of transmission media

Characteristics of a Data Communication System

Effectiveness of a Data Communication System:

• •       Delivery

•       Accuracy

•       Timeliness

•       Jitter

Components of a Data Communication system

A data communications system has five components

Protocol (Rules)

Message

Sender

Receiver

Transmission Medium

Data Representation and Data Flow

Forms of Information

•       Text

•       Numbers

•       Images

•       Audio

•       Video

Data Flow between two devices:

•       Simplex

•       Half-Duplex

•       Full-Duplex

Networks

•       Network:

Interconnection of a set of devices capable of communication

•       Host

•       Connecting Device

Network Criteria

A network must be able to meet a certain number of criteria:

•       Performance

ü  Throughput

ü  Delay

ü  Reliability

•       Security

Physical Structures

Physical Network Attributes

•       Link

•       Type of Connection

ü  Point-to-Point

ü  Multipoint

Physical Topologies

•       Physical Layout of Network

•       Links + Nodes = Topology

•       Physical Topologies:

ü  Mesh

ü  Star

ü  Bus

ü  Ring

Networks Types

•       Network classification:

ü  Size

ü  Geographical

       Coverage

ü  Ownership

ü  Local Area Networks   (LANs)

•       Wide Area Networks (WANs)

Local Area Networks

•       Usually Privately owned

•       Connects some hosts in a single office, building, or campus

•       Can be as simple as two PCs and a printer in someone’s home office

•       Can extend throughout a company

•       Host Address

Wide Area Network

•       Wider geographical span than a LAN

•       Spans a town, a state, a country, or even the world

•       Interconnects connecting devices such as switches, routers, or modems

•       Normally created and run by communication companies

•       Point-to-Point WAN

•       Switched WAN

•       Internetwork

Point-to-Point WANs

Switched WANs

Internetwork

Switching

•       Switching

ü  Circuit-Switched Network

ü  Packet- Switched Network

The Internet

•       An internet (note the lowercase i) is two or more networks that can communicate with each other

•       The Internet (uppercase I ), and is composed of thousands of interconnected networks.

•       Accessing the Internet

Internet History

•       Telegraph and Telephone networks, before 1960:

ü  Constant-rate communication only

ü  ARPANET- Packet Switched

•       Birth of the Internet &TCP/IP

•       MILNET

•       CSNET

•       NSFNET

•       Internet Today

Internet Standards and Administration

•       Internet draft

•       Request for Comments (RFC)

ü  Proposed Standard

ü  Draft Standard

ü  Internet Standard

ü  Historic

ü  Experimental

ü  Informational