[ndnSIM] initial RTO value

Alex Afanasyev alexander.afanasyev at ucla.edu
Tue May 28 11:11:41 PDT 2013


Hi Yaogong,

Thanks for opening an issue and finding the problem!  I just incorporated your commit that fixes the incorrect initialization of attributes.

As of now, the initial RTO is 1 second, and later cannot become smaller than the minimum, which is by default set to 200ms.

---
Alex

On May 28, 2013, at 8:21 AM, Yaogong Wang <ywang15 at ncsu.edu> wrote:

> Hi Alex,
> 
> I believe the initial RTO should not be 200ms. According to the code, RTO is set to m_currentEstimatedRtt + 4 * m_variance bounded by minRto and maxRto. By default, m_currentEstimatedRtt is initially set to 1s (InitialEstimation) and m_variance to 0. Hence, the initial RTO should be 1s which is within minRto=200ms and maxRto=200s.
> 
> The current code does set initial RTO to 200ms due to a bug that sets m_currentEstimatedRtt to 0 initially. I have reported the bug here: https://github.com/NDN-Routing/ndnSIM/issues/40
> 
> Thanks,
> Yaogong
> 
> 
> On Wed, May 22, 2013 at 4:40 PM, Alex Afanasyev <alexander.afanasyev at ucla.edu> wrote:
> Hi huyao,
> 
> Yes. There is an initial RTO value and it is 200ms.  You can control this value by setting "ns3::ndn::RttEstimator::MinRTO" value.  ndnSIM uses a modified version of RTT estimator, originally in Internet module: https://github.com/NDN-Routing/ndnSIM/blob/master/utils/ndn-rtt-estimator.cc.
> 
> --
> Alex
> 
> On May 22, 2013, at 10:52 AM, yao hu <huyao0107 at gmail.com> wrote:
> 
>> Hi Alex,
>> 
>> Is there a default initial RTO value for consumer node? RTO should be calculated based on the observed RTT samples, but how about the first Interest timeout for some reason? If there is a default initial value, is it 200ms?
>> 
>> Thanks for your explanation~
>> 
>> Regards,
>> huyao
>> 
>> 
>> 
>> 
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> 
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> 
> 
> -- 
> ============================
> Yaogong Wang, PhD Candidate
> Department of Computer Science
> North Carolina State University
> http://www4.ncsu.edu/~ywang15/
> ============================

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