EVOLUTION OF INTERNET

 THE INTERNET HAS REVOLUTIONIZED MANY ASPECTS OF OUR DAILY LIVES.IT HAS AFFECTED THE WAY WE DO BUSINESS AS WELL AS THE WAY WE SPEND OUR LEISURE TIME.COUNT THE WAY YOU HAVE USED THE INTERNET RECENTLY.PERHAPS YOU HAVE SENT E-MAIL TO A BUSINESS ASSOCIATE ,PAID A UTILITY BILL,READ A NEWS PAPER FROM DISTANT CITY,OR LOOKEDUP A LOCAL MOVIE SCHEDULE ALL BY USING THE INTERNET.             

INERNET SERVICE PROVIDERS ARE BACKBONE NETWORKS CREATED AND MAINTAINED BY SPECIALISED COMPANIES.TO PROVIDE CONNECTIVTY BETWEEN THE END USERS,THESE BACKBONE NETWORKS ARE CONNECTED BY COMPLEX  SWITCHING STATIONS CALLED NETWORK ACCESS POINTS.SOME INERNET SERVICE PROVIDERS  ARE ALSO CONNECTED TO ONE ANOTHER BY PRIVATE SWITCHING STATIONS CALLED PEERING POINTS.THESE NORMALLY OPERATE AT A HIGH DATA RATE.

REGIONAL INTERNET SERVICE PROVIDERS ARE SMALLER INERNET SERVICE PROVIDERS THAT ARE CONNECTED ONE OR MORE SERVICE PROVIDERS.THESE ARE THIRD LEVEL OF THE HIERARCHY WITH A SMALLER DATA RATE.

LOCAL INTERNET SERVICE PROVIDERS PROVIDE DIRECT SERVICE TO THE END USERS.THE LOCAL SERVICE PROVIDERS CAN BE CONNECTED TO REGIONAL SERVICE PROVIDERS OR DIRECTLY TO NATIONAL SERVICE PROVIDERS.MOST END USERS ARE CONNECTED TO THE LOCAL SERVICE PROVIDERS.

IN COMPUTER NETWORKS ,COMMUNICATION OCCURS BETWEEN ENTITIES IN DIFFERENT SYSTEMS.AN ENTITY IS ANYTHING CAPABLE OF SENDING OR RECEIVING INFORMATION.HOWEVER ,TWO ENTITIES  CANNOT SIMPLY SEND BIT STREAMS TO EACH OTHER AND EXCEPT TO BE UNDERSTOOD.FOR  COMMUNICATION TO OCCUR,THE ENTITIES MUST AGREE ON A PROTOCOL.A PROTOCOL IS A SET OF RULES THAT GOVERN DATA COMMUNICATIONS.A PROTOCOL DEFINES WHAT IS COMMUNICATED,HOW IT IS COMMUNICATED,WHEN IT IS COMMUNICATED.THE KEY ELEMENTS OF A PROTOCOL ARE SYNTAX,SEMANTICS AND TIMING.

THE TERM SYNTAX REFERS TO THE STRUCTURE OR FORMAT OF THE DATA MEANING THE ORDER IN WHICH THEY ARE PRESENTED.FOR EXAMPLE,A SIMPLE PROTOCOL MIGHT EXPECT THE FIRST 8 BITS OF DATA TO BE THE ADDRESS OF THE SENDER,THE SECOND 8 BITS TO BE THE ADDRESS OF THE RECIEVER,AND THE REST OF THE STREAM TO BE THE MESSAGE ITSELF.

SEMANTICS REFERS TO THE MEANING OF EACH SECTION OF BITS.HOW IS A PARTICULAR PATTERN TO BE INERPRETED,AND WHAT ACTION IS TO BE TAKEN BASED ON THE INERPRETATION.FOR EXAMPLE ,DOES AN ADDRESS  IDENTIFY THE ROUTE TO BE TAKEN OR FINAL DESTINATION OF THE MESSAGE.