[ndnSIM] initial RTO value

[yao hu]

Hi Alex and Yaogong,

Thanks for your both explanations. For my understanding, this RTO is used
in setting up a retry-timer. But I am a little confused by the word "retry"
in "retry-timer". This "retry" refers to the retransmission for end users
for sure, but it also refers to the retry for intermediate nodes (retry
other alternative faces than failed one)?

Regards,
huyao



2013/5/29 Alex Afanasyev <alexander.afanasyev at ucla.edu>

> 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/
> ============================
>
>
>


-- 
**************************************************
早稲田大学 基幹理工学研究科 情報理工学専攻
後藤滋樹研究室
胡 曜 (HU Yao)
E-mail : huyao at goto.info.waseda.ac.jp
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