Download - Data Communication Networks
Data Communication
Exchange of data between two or more
devices using some transmission
medium.
Another explanation could be:
Electronic transmission of information
that has been encoded digitally (as for
storage and processing by computers)
Components of Data Communication System
Message (text, image, numbers, audio, video)
Sender(computer, workstation, telephone, camera etc.)
Receiver
Transmission Medium(twisted-pair, optical fiber, coaxial cable, radio waves)
Protocol(set of rules that govern data communication)
Mode of Data Communications
Simplex (unidirectional)
Half-Duplex (bidirectional)
Full-Duplex(bidirectional)
Applications of Networks
Resource Sharing
Hardware (Computing Resources, Disks, Printers, etc.)
Software (Application Software)
Information Sharing
Easy accessibility from anywhere (Files, Databases, etc.)
Search Capability (WWW)
Communication
Message Broadcasting
Network Criteria
Performance:
Transmit Time, Response Time, Throughput
Reliability:
Frequency of failure, Time to recover
Security:
Unauthorized Access, Protecting Data
Physical Topology
It refers to the way how the network is laid out physically.
Geometric representation of the relationship of all the links and linking devices
Categories of Networks
Local Area Network (LAN)
Wide Area Network (WAN)
Metropolitan Area Network (MAN)
Local Area Network
Privately owned computer network that connects computers and other information processing device.
LAN size – Few Kilometers
LAN Examples
Ethernet (CSMA/CD)
LocalTalk (CSMA/CA)
Wireless LAN
Token Ring
Wide Area Network
Network that covers a broad area
Example- Any telecommunications network that links across metropolitan, regional, or national boundaries.
Metropolitan Area Network(MAN)
Designed to extend over the entire city.
It may be a single network as a cable TV network OR
It may be means of connecting a number of LANs into a larger network
The main reason for distinguishing MANs as a special category is that a standard has been adopted for them. It is DQDB(Distributed Queue Dual Bus) or IEEE 802.6.
Protocols and Standards
Protocol: Syntax
The structure or format of data, i.e. the order in which they are presented.
Semantics
Semantics refers to the meaning of each section of bits.
Timing
When and how fast data to be sent.