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LECTURE
Standards
“A standard provides a model for development that makes it possible for a product to work regardless of the individual manufacturer|”
A great deal of coordination and cooperation is required by the devices to communicate A device prepared by a specific manufacturer may not be compatible with the devices prepared by other manufacturers Unavailability of standards creates problems and puts a halt to product growth
An example of non-standardized products is AUTOMOBILES
Why Standards are Essential?
Standards are therefore essential in: o Creating and Maintaining an Open and competitive Market for Equipment Manufacturers o Guaranteeing National and International Interoperability of Data and Telecommunications Technology and Equipment
Let us understand this using an EXAMPLE
NOTE
- K sources and L receivers leads to KL protocols and 2K*L implementations
- If common protocol used, K + L implementations needed
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Categories of Data Communication Standards
Standards
De facto
(By Fact)
De jure
(By Law)
Proprietary Non Proprietary
De facto (By fact or By Convention)
Standards not approved by an organized body but have been adopted as standards through their widespread use
De jure (By Law or By Regulation)
Standards that have been legislated by an officially recognized regulation body
Subdivision of De Facto Standards
PROPRIETARY (Closed Standards)
Standards that are originally invented by a Commercial Organization as a basis for the operation of its products they are wholly owned by that company. They are also called Closed Standards because they close off Communication between systems
NON - PROPRIETARY (Open Standards)
They are originally developed by groups or committees that have passed them into public domains. They are also called Open Standards because they open Communication between different systems
Standard Organizations
Standards are developed mainly by 3 entities:
Standard Creation Committees Forums Regulatory Agencies
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Each Forum Concentrate on a specific technology and present their conclusions to the standard bodies
Frame Relay Forum ATM Forum Internet Society & IETF
Regulatory Agencies All communication technology is subject to regulation and laws by government agencies. The purpose is to protect Public Interest by regulating Radio, Television and Cable Communications.
FCC
Before we go into the details of how data are transmitted from one device to the other, it is important to understand:
o The relationship between communication devices. o How the devices connect with each other in a System? o How do they do the exchange of information?
Five Concepts provide the basis
o Line Configuration o Topology o Transmission Mode o Categories of networks o Internetworks
LINE CONFIGURATION
“Line Configuration refers to the way two or more devices attach to a Link ”
A link is the physical communication path that transfers data from one device to the other. Link can be thought of as a Line drawn between two points. For communication to occur, two devices must be connected to each other using a link.
Line Configurations
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Line
Configuration
Point-to-Point Multipoint
Spatially Shared Time Shared
Point-to-Point Line Configuration
Dedicated Link between two devices. Entire Capacity of the channel is reserved for TX B/w these two devices. Mostly point-to-point connection use wire/cable to connect with each other. But Microwave, Satellite Links can also be used Data and Control information pas directly between entities with no intervening agent Examples :
TV Remote Control and TV Control Systems Mobile Phone (when talking) and Base Station (Antenna)
Multipoint Line Configuration More than two devices share the Link that is the capacity of the channel is SHARED now. With shared capacity, there can be two possibilities in a Multipoint Line Config:
Spatial Sharing : If several devices can share the link simultaneously, its called Spatially shared line configuration
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