Is p2p channel delay attribute transmission or propagation delay?

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Charis Ch

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Oct 31, 2015, 6:14:08 PM10/31/15
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In the tutorial it clearly states that the "delay" attribute of p2p channel is transmission delay.
But after looking at the code for several days I came to the conclusion that it is propagation delay. 
https://www.nsnam.org/docs/release/3.24/doxygen/classns3_1_1_point_to_point_channel.html#a81318c3ab2fdd02f5663fb0e8fcdeabf
In fact how can we set netdevice's datarate with fixed packetsize and fixed transmission delay?? 
I have read many unanswered posts regarding this subject, so please, I need your two cents.

Thanks!


P.S. Post #1! Yeahh!!

Tommaso Pecorella

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Nov 1, 2015, 3:04:23 AM11/1/15
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Define the difference between transmission delay and propagation delay please...

Thanks,

T.

Charis Ch

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Nov 1, 2015, 9:16:13 AM11/1/15
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I think that the definitions are known. Transmission delay is the time that the net device needs to push a whole packet into the channel (packet size/datarate) and propagation delay is the time that the packet travels throught the channel to the receiver. Isn't it?

Tommaso Pecorella

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Nov 1, 2015, 12:21:25 PM11/1/15
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Well, it's debatable. I'd call the first transmutation time, not delay. Anyway, you're right about the fact that the p2p "play" attribute is the propagation delay. Tbh *any* device "delay" attribute is the propagation delay, and this is fairly obvious: the transmission delay (or time) is dependent on the channel data rate and the packet length. Thus, it can not be an attribute.
Moreover, in many NetDevices there's no "delay" attribute at all, because the propagation delay is dependent on the signal speed in the medium (usually close enough to the speed of light in the vacuum) and the nodes mutual distance.

Hope this clarifies a bit,

T.

Charis Ch

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Nov 1, 2015, 1:16:55 PM11/1/15
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Thank you very much for your prompt and detailed response!

SUBIN JOSEPH

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Oct 21, 2016, 5:00:20 AM10/21/16
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Dear Tommaso,
As related to this,I would like to ask one question.
Does propagation delay change with respect to nodes mutual distance in csma /p2p channel.??

I have written a script where I measured the round trip time between two nodes(in csma channel) in two ways.(1st method:distance between nodes is 100m, 2nd method:distance between nodes is 1lakh meters).

I could not find any difference in round trip time.I have read in an article that theoretically there is a propagation delay of 6560 ns in every 1 km distance for csma channel.Is it so?

How can i set the propagation delay in wired links with respect to the nodes distance?( I know that there is an attribute called delay in csma and p2p channel.But it seems to be constant irrespective of distance)

Thanks and Regards
Subin

Tommaso Pecorella

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Oct 22, 2016, 11:11:36 AM10/22/16
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The answer is no, but... why don't you look at the code ?

T.

Noam Munz

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Nov 10, 2022, 8:34:26 AM11/10/22
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Did you figure out how to set propagation with respect to the node's distance? 
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