regarding bca course subject

1. FRAMING IN COMPUTER NETWORK

2. WHAT IS FRAMING
•FRAMING IS A POINT-TO-POINT CONNECTION BETWEEN
TWO COMPUTERS OR DEVICES CONSISTS OF A WIRE IN
WHICH DATA IS TRANSMITTED AS A STREAM OF BITS.

3. HOW IT WORKS?
•THE DATA LINK LAYER, NEEDS TO PACK BITS INTO FRAMES, SO THAT EACH IS DISTINGUISHABLE
FROM ANOTHER.
•THE DATA LINK LAYER PREPARES A PACKET FOR TRANSPORT ACROSS THE LOCAL MEDIA BY
ENCAPSULATING IT WITH A HEADER AND A TRAILER TO CREATE A FRAME.

5. PARTS OF FRAME
•FRAME HEADER- IT CONTAINS THE SOURCE AND DESTINATION ADDRESSES OF THE FRAME.
•PAYLOAD FIELD- IT CONTAINS THE MESSAGE TO BE DELIVERED.
•TRAILER- IT CONTAINS ERROR DETECTION AND ERROR CORRECTION BITS.

6. TYPES OF FRAMING
FIXED-SIZED FRAMING-
•HERE, THE SIZE OF THE FRAME IS FIXED AND SO THE FRAME LENGTH ACTS AS DELIMETER OF
THE FRAME.
•CONSEQUENTLY, IT DOES NOT REQUIRE ADDITIONAL BOUNDARY BITS TO IDENTIFY THE START
AND END OF THE FRAME.
VARIABLE-SIZED FRAMING-
• HERE, THE SIZE OF EACH FRAME TO BE TRANSMITTED MAY BE DIFFERENT.
• SO ADDITIONAL MECHANISMS ARE KEPT TO MARK THE END OF ONE FRAME AND THE
BEGINNING OF NEXT FRAME.

7. •BYTE-STUFFING- A BYTE IS STUFFED IN THE MESSAGE TO DIFFERENTIATE FROM THE DELIMETER.
THIS IS ALSO CALLED CHARACTER-ORIENTED FRAMING.
•BIT-STUFFING- A PATTERN OF BITS OF ARBITRARY LENGTH IS STUFFED IN THE MESSAGE TO
DIFFERENTIATE FROM THE DELIMETER. THIS IS ALSO CALLED BIT-ORIENTED FRAMING.
IF PATTERN OCCURS IN MESSAGE, THEN TWO APPROACHES ARE
USED TO AVOID SITUATION