ISRO2016-69

Question

In Ethernet CSMA/CD, the special bit sequence transmitted by media access management to handle collision is called

• A. Preamble
• B. Postamble
• C. Jam
• D. None of these

Comments

C?

Answer 1

The ethernet CSMA/CD,the special bit sequence is transmitted by media access management to handle collision is called Jam signal.

Hence,Option(c)Jam. 

Comments

Lets explore the answer.

As we know the range of collision occurence is (0-pt) and of collision detection is (0-2*pt) where pt=propagation time.

Consider 4 stations:

A      B     C      D

If collision occur between signals of A and D at position between C and D

then C will detect collision before 2*pt so it need to transmit some signal to all other stations that a collision had already occurred here you all please JAM your any more signal,don't transmit anything or it will also result in  collision.

It keeps transmitting this Jamming signal till 2*pt till every channel get to know about collision and then after 2*pt they all go and implement Exponential back off algorithm..together

Answer 2

Lets explore the answer.

As we know the range of collision occurence is (0-pt) and of collision detection is (0-2*pt) where pt=propagation time.

Consider 4 stations:

A      B     C      D

If collision occur between signals of A and D at position between C and D

then C will detect collision before 2*pt so it need to transmit some signal to all other stations that a collision had already occurred here you all please JAM your any more signal,don't transmit anything or it will also result in  collision.

It keeps transmitting this Jamming signal till 2*pt till every channel get to know about collision and then after 2*pt they all go and implement Exponential back off algorithm..together