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How to calculate window size in Stop and Wait, Select and Repeat, GBN.

Some where I have seen window size as w = 1+2a

where a = PT/TT.

and some where it is calculated as:

if we have

RTT = 160msec

BW = 256 Kbps

Data size  = 64Bytes

then window size as

[160 * 10^(-3) * 256 * 10^(3)]/(64 * 8)

which one to follow.

And how to calculate Throughput and Efficiency ib all three protocol u can take above configuration to derive result.

@Shubhanshu

window size = (1+2a)*efficiency,

if efficiency = 100%, then window size = 1+2a
Ok so it means that in S and W we keep window size as 1 thats why we get the  tt/(tt+2pt) as efficiency.

and for other two we keep window size as acc to given question

and for throughout we do product of eff and BW right?
yes.
@joshi_nitish check this

Some where in the soln I have seen that processing time is also used to includes in the denomenator.

I think eff is transfer time of data packet div by total time which is tt of data and pt of data and tt of ack and pt of ack and processing of data and processing of ack

right??

+1 vote

this is how to find efficiency,throughput and window size

Some where in the soln processing time also used to include in the denomenator.

I think eff is transfer time div by total time which is tt of data and pt of data and tt of ack and pt of ack and processing of data and processing of ack

right??
generally we ignore processing time...but in some ques  if processing time is given then we have to include that also...then in that case total time=processing time+RTT+transmission+............
Is it will be directly given in the question or we have to calculate if it is not given in the question?

for both ack and data pkts.
Processing time or any other extra information would be given directly i the question... You do one thing just analyze the previous year gate question, then you will get an idea.
Thanks !!!