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Q. When calculating channel efficiency, they have not mentioned propagation delay (i.e. the delay it takes for last bit to cross the link in successful transmission)

https://gateoverflow.in/?qa=blob&qa_blobid=300869075225723175

https://gateoverflow.in/?qa=blob&qa_blobid=3762516041534646972

Q. But here they have mentioned propagation delay (i.e. the delay it takes for last bit to cross the link in successful transmission)

[[ second part ethernet efficiency ]]

https://gateoverflow.in/?qa=blob&qa_blobid=13532445277728198980

https://gateoverflow.in/?qa=blob&qa_blobid=415976416681037505

Please tell should I take the propagation delay of the last bit in calculating efficiency and throughput ?

@sourav+anand
@srestha

Propagation delay doesnt depend upon the size of the packet.It depends upon the speed of the signal in the channel.
Rather, I think its a channel property. Its like the difference between 8 lane highways and 2 lane highways.

I say to Lambhorghini that drive on 2 lane highway. It will go like Maruti Alto. But if its 8 lane road, it will be like superfast bullet train.

Here the car was same, channels were different.

Similarly, packet is always the same but the time required to cross a channel depends upon the channel I think.

edited

SO I should take propagation time

CSMA/CD $Throughput = \frac{FrameSize}{TransmissionPeriod+CollitionPeriod+PropagationPeriod}$

@Sushant+Gokhale

edited
Propagation time is

length of channel/ speed of signal in channel.