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Why in csma cd transmission time=2*propogation time
asked in Computer Networks by Junior (729 points) 1 20 47 | 194 views

Actually it should be transmission time >= 2*propagation time

I've tried to explain it here: http://gateoverflow.in/29736/frame-size-jamming-signal

3 Answers

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Best answer

In CSMA/CD ,in worst case maximum time to reach the frame bit to other end is Tp and then Tp time is required to get back the collision signal to node again.So it takes one RTT and at that time node still should be sending the data,then only it can be sure that the collision signal it received,belonged to its frame.And it have to retransmit the packet again.

So Transmission Time >= 2* Propogation Time

In this case sender is sending the data until collision signal is reached back to sender,so it can be make sure whether its packet got involved in collision or not (including worst case too).

answered by (237 points) 1 2 8
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+1 vote
To detect collision in worst case:
transmission time  >= 2 * propagation time.
answered by Boss (8.7k points) 14 35 91
edited by
0 votes
actually in csma\cd the condition for collision detection in the worst case is Tt>=2*Tp

for a collision detection the sender should transmitted its packet till the carrersence is not returning back to the sender  and in worst case the carrer will travell 2*tp
answered by (121 points) 2


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