udp packet delay

[Lily]

Hi all,

In my test, I use udp client to generate traffic and use extract statistics from flowmonitor.  I calculate the average packet delay with (delaysum)/ rxPackets.

I found that when the bandwidth is not saturated the average delay keep same.   I think the delay should increase with the growth of flow traffic rate.

For example, the delay is x , when flow traffic rate is 1Mbps, and then the delay is y, when flow traffic rate is 2Mbps.   x should be greater than y.  But in ns3 , they are same. 

 

Could you give me some hints on how to solve the problem? Or what's the situation in real network?  Thanks.

[Tommaso Pecorella]

It heavily depends on the technology you're simulating. In most systems the difference is not noticeable unless you use really advances statistical analysis, and also in these cases it can be hard to notice.

As an example, Wi-Fi tx delay depends only on the back off timers, and the are changing only if a node experiences a collision, which is not that common (unless very close to the saturation point).

T.

[Wenrui Ma]

One more question, we can set interval and packet size for UDP application. I think it uses constant traffic model.  I want to apply burst model on UDP application.  The average throughput is still same, but in some duration there's no packets and in other duration there's a packet burst. But I have no idea now. Do you have any suggestion? Thanks.

Regards,

Wenrui Ma

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[Konstantinos]

Hi,

You can use OnOffApplication to generate UDP traffic with random On and Off times. 

This can mimic bursty arrival process.

Regards,

K.

On Tuesday, November 3, 2015 at 12:58:09 AM UTC, Lily wrote:

One more question, we can set interval and packet size for UDP application. I think it uses constant traffic model.  I want to apply burst model on UDP application.  The average throughput is still same, but in some duration there's no packets and in other duration there's a packet burst. But I have no idea now. Do you have any suggestion? Thanks.

Regards,

Wenrui Ma

On Mon, Nov 2, 2015 at 6:54 PM, Tommaso Pecorella <tomm...@gmail.com> wrote:

It heavily depends on the technology you're simulating. In most systems the difference is not noticeable unless you use really advances statistical analysis, and also in these cases it can be hard to notice.

As an example, Wi-Fi tx delay depends only on the back off timers, and the are changing only if a node experiences a collision, which is not that common (unless very close to the saturation point).

T.

On Monday, November 2, 2015 at 10:28:39 PM UTC+1, Lily wrote:

Hi all,

In my test, I use udp client to generate traffic and use extract statistics from flowmonitor.  I calculate the average packet delay with (delaysum)/ rxPackets.

I found that when the bandwidth is not saturated the average delay keep same.   I think the delay should increase with the growth of flow traffic rate.

For example, the delay is x , when flow traffic rate is 1Mbps, and then the delay is y, when flow traffic rate is 2Mbps.   x should be greater than y.  But in ns3 , they are same. 

 

Could you give me some hints on how to solve the problem? Or what's the situation in real network?  Thanks.

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[Wenrui Ma]

Thanks. It works.

Regards,

Wenrui Ma

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