[ndnSIM] Issue with RttEstimator.

[Saeid Montazeri]

Hi all,

Sorry, m_retxTimer is the period that a CcnxConsumer checks to see
whether there is any sent interest which gets expired or not.

I think m_retxEvent should be canceled in the
CcnxConsumer::StopApplication (). Am I right?

Best Regards,
Saeid

On Mon, May 19, 2014 at 12:51 AM, Saeid Montazeri
<saeid.montazeri at gmail.com> wrote:
> Hi all,
>
> I found an strange behaviour with ndnSIM related to RttEstimator. I made a
> very simple scenario to debug. There are five nodes in a linear topology.
> Suppose one consumer node is connected to router_0 and one producer node is
> connected to router_4.  There are two cases:
> 1) the consumer node installs CcnxConsumerCbr to request the content on the
> producer with rate of 1 CcnxConsumerCbr per second and the simulation time
> is 10 second.
>
> 2) tthe consumer node installs CcnxConsumerCbr to request the content on the
> producer with rate of 0.1 CcnxConsumerCbr per second and the simulation time
> is 100 second.
>
> The execution times are very different. That is, case 2 has longer execution
> time. After digging dipper, I found that the number of call for
> RttEstimator:RetransmitTimeout makes the difference.
>
> RetransmitTimeout is called by CcnxConsumer::CheckRetxTimeout which
> periodically calls itself with the period of m_retxTimer with the default
> value of 50ms.
>
> This makes a real issue for the scenarios with large number of CcnxConsumer
> in terms of execution time. That is, this leads to a lot of unnecessary
> events. In addition, I found that for my evaluation which is network of
> caches performance (network with rare congestion), it is not necessary to
> have m_retxTimer very small. I changed it to 500ms and the execution time
> drastically is decreased.
>
> Please let me know your comments, specially about the right value of
> m_retxTimer for different scenarios. I think the smaller the m_retxTimer
> leads to faster detection of the network RTT fluctuation by consumers.
>
> In addition, do you think that I need to change the default value of
> m_minRto and m_maxRto?
>
> Best Regards,
> Saeid
>
>