Question about Throughput calculation

[Konstantinos]

Hey,

I want to calculate the throughput in a wifi scenario.
From examples/wireless/hidden-terminal.cc I found this code. This "10.0" i suppose is the time of the simulation. Shouldn't this be (timeLastRxPacket - timeFirstRxPacket).GetSeconds() ??

...
line 159: std::cout << "  Throughput: " << i->second.rxBytes * 8.0 / 10.0 / 1024 / 1024  << " Mbps\n";
...

[Mathieu Lacage]

On Wed, Mar 2, 2011 at 17:36, Konstantinos <dinos.k...@gmail.com> wrote:

> I want to calculate the throughput in a wifi scenario.
> From examples/wireless/hidden-terminal.cc I found this code. This "10.0" i
> suppose is the time of the simulation. Shouldn't this be (timeLastRxPacket -
> timeFirstRxPacket).GetSeconds() ??

I suspect that it really depends on what your definition of throughput
is. In this case, the numeric result should not change much since the
applications start sending packets really early in the simulation.

Mathieu
--
Mathieu Lacage <mathieu...@gmail.com>

[idrees.a...@gmail.com]

Sir Konstantinos and Mathieu Lacage

i am trying to simulate a research paper on wimax whose title is "Dynamic QoS based bandwidth allocation framework for broadband wireless networks", i have created topology for it. sir its scheduler is based on two primary parameters  i.e. throughput and allocated bandwidth, sir in my implementation i have added flow monitor and i am getting values of throughput, but i have two questions:
1) how to get throughput of each packet sent or received  and
2) while getting the values of throughput i have to call scheduler so is it possible to call scheduler after flow monitor implementation?

[Konstantinos Katsaros]

Hi

1) Throughput is a statistical metric, not calculated per packet. Throughput means how many packets/bytes/bits per unit of time.

2) You can put FlowMonitor inside your scheduler and get throughput statistics e.g. every 1, 2, 3 .. seconds.

Regards,

Konstantinos Katsaros

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[idrees.a...@gmail.com]

Sir
thanks alot for clarification and giving such a kind advice.

[dio...@gmail.com]

Hi Konstantinos,

I am not sure if this is the right place to ask this question. However, based on your answer I was wondering if someone is able to define freely what is a "flow" for him/her.
I mean that, I may want to define as flow1 the data transferred from node A and node B from t1 = 5 until t2 = 15 seconds. Based on this definitition, I can use FlowMonitor and estimate the throughput (what I consider as throughput) for this specific flow1.

Thanks in advance,
Dionysios

[Konstantinos]

Dear Dionysios,

A flow is well defined in terms of transport layer (either TCP or UDP) [1] and is the combination of 5 elements: source IP, source port, destination IP, destination port and the protocol type.
FlowMonitor uses the same classification but I think it leaves out the protocol type (not sure though). So you can identify your flow (flow1) if you know those 4 parameters.
You can configure FlowMonitor to start 'looking' into the packets at t1=5sec using the start function of flowmonitor and make it stop at t2=15sec with the stop. For more information read the documentation [2].

void	Start (const Time &time)
	Set the time, counting from the current time, from which to start monitoring flows.

void	Stop (const Time &time)
	Set the time, counting from the current time, from which to stop monitoring flows.

Regards,
Konstantinos

[1] http://en.wikipedia.org/wiki/Traffic_flow_%28computer_networking%29
[2] http://www.nsnam.org/doxygen/classns3_1_1_flow_monitor.html

[salma subh]

is there any example about how to calculate instantaneous throughput using flow monitor sir ?

[Andres Glücksberg]

hello Konstantinos,

what do the number in the line 159 mean?

 8.0 / 10.0 / 1024 / 1024  

thanks

[Konstantinos]

Hi Andres,

The first 8.0 is to convert the bytes in bits (because the "second.rxBytes" returns you the total received bytes
The 10 (which was also my initial question) should be the time difference from the first received packet till the last.
The last two 1024 is to convert the bits into kbits and Mbits respectively.

[hafza kareem]

Hello Konstantinos,

Could you please share the answer for this question if you have figured it.