Bit Stuffing

Question

Answer is 4 or 6 ?

Comments

https://gateoverflow.in/153783/bit-stuffing

Answer 1

In general with a flag 01^k0 the bit stuffing is required whenever 01^k-1 appears in the original data stream.

1011010110110110111110   so total 3 times 0 is stuffed.

Answer 2

Flag : 01110

Data Frame: 1011101111011111110

Data after bit stuffing: 1011010110110011011011010

6 0's will be stuffed! for your reference see the following screenshot from the book:

 

Comments

@manuOOx

Yes I do agree I was also getting 6 0's according the concept given in book but why people are answering 3 0's.

But I think If you see there is no need to add last 3 0's(stuffed) at the end where run of 7 1's is written because there will be no confusion of 011 here and we need to stuff only 3 0's.

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@Ashwani when you add a 0, that itself prepares another pattern for example 

1011-0-1011-0-11-0-011-0-11 -0-11-0-10 when this 0 is inserted then it self prepared a continuous pattern of 011 hence we have to stuff 5th bit, and for the same reason we have to stuff 6th 0.

system will remove any bit after two consecutive 1's,  system believes that after 2 consecutive 1's one 0 is stuffed by the sender. By looking ( we have eyes but system doesn't have) at data we can recognize it but not the system.

Answer 3

Stuff bit pattern :01110  
dataFrame :1011101111011111110  
After stuffing 1011010110110110111110: 3 Bit stuffing

Answer 4

ans is 6

1011010110110011011011010