Self Doubt :Bit Stuffing

Question

End delimeter is → 0111

data to be sent 0111111111.

What is the data we should send to the reciever?

Comments

@srestha

Help!

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@hirak what is the term "URGENT" indicating in the title

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It will be 01101111111.

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@srestha

I also thought the same but see this --> https://gateoverflow.in/146996/result-after-bit-stuffing

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Since the end delimiter is 0111 we need to make sure that there isn't 0111 as a part of data.

Data:0111111111
To get rid of 0111 from the data we can add a 0 after 011 to make it 0110 1

And do this until there isn't 0111 as a subset.

You will get the data as:

01101101101101

Also read: https://gateoverflow.in/141461/computer-networks-bit-stuffing

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but on the receiver side receiver automatically removes the 0 whenever it encounters it after 011..! so why dp we need to stuff 0 each and every time..!

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Because the first time you stuff 0 you get:

01101111111

As you can see now the new data (partially stuffed data) contains 0111 which can be mistaken as the end delimiter and it will consider the data as 011.

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@Hirak @sakharam

Can u mention exact line of forouzan , which tells that??

I never seen such a thing in any standard question.

Plz. mention specifically the line from forouzan which mention that.

It may be, but I am not getting where forouzan mentioned that.

Tell me the line. Quote it from book plz.

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@sakharam

whenever the reciever sees 011 it removes the next 0..so 011 can never occur again..

@srestha

I agree with your ans..I also have the same concept..but in other ans it is different

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@Hirak
Check @Ayush ans again
it told
100011111P110011111P0100011111P111111000011111P

see the red portion they havenot added 0.

That means which 0 , we are adding extra, that is not considered as flag bit

right?

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Yes...

that means our ans will be 0110111111..right?

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yes, will not be wrong for sure

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@Hirak

@srestha

Check this: http://web.mit.edu/modiano/www/6.263/lec2.pdf   (page 8) its done differently.

This is same as done in CN by Tanenbaum, Communicaition Networks by Garcia and Widjaja and also in Data and Computer Communications by Stallings .

Above image Src: Tanenbaum

Above image src: CN by Garcia and Widjaja

Above image src: William Stallings

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@sakharam

If u get such a GATE/ISRO question, and answer like this, then plz inform me. I donot think such thing applied in any answer

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Yes @srestha mam. In the Forouzan's exercise there is a question whose answer will vary depending on which procedure we follow. But I didn't find any official solution (from the publisher or author). following is the question:

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@sakharam

Okay..there is lots ambiguity surrounding this.. Anything like this has not been asked in GATE till now, guess they have also found it ambiguous.. :)

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Yes, I hope such questions never comes and I tried to search an implementation of this but couldn't find it.

Answer 1

End delimeter is → 0111

data to be sent 0111111111.

ans-

receiver side data -01101101101101

after 11 puts 0.

Answer 2

End delimiter is 0111

Data sent is 0111111111

Here we have to place 0s in such a way that the receiver is able to distinguish up to what part data is present. 0111 is the end delimiter. Our data is containing end delimiter we have to find a way such that the receiver is able to know that 0111 is not end delimiter but data and that's why we will put 0s after each 011. While putting 0s if new 0111 sub strings formed then for such cases also we will be putting 0s after 011

so, I think answer will be 01101101101101