[ndnSIM] how to modify nonce field in Interest packet

[yao hu]

I am sorry to append some words.. When link failure or network congestion
happens,

1) end host or consumer is responsible to retransmit the interest on other
alternative interfaces
2) intermediate node retries the retransmitted interest to other
alternative interfaces

So is there any strategy difference between 1) and 2) ? what part of
functions or methods shows that retransmission or retry stategies?

Thanks a lot again!


2013/5/2 yao hu <huyao0107 at gmail.com>

> Hi Alex,
>
> Thanks a lot. I am looking into the related code but I am not sure if it
> also applies to requester? Because there is no PIT entry to check for a
> requester or consumer. What to do to change or control the requester
> behavior when retransmitting the interest?
>
> Regards,
> huyao
>
>
> 2013/5/2 Alex Afanasyev <alexander.afanasyev at ucla.edu>
>
>> Hi huyao,
>>
>> Not really.  An application has basically no control on how exactly and
>> to where its interests are getting forwarded.
>> Moreover, an application does not know (and should not know) anything
>> about other faces of an NDN router.
>>
>> Actually, there is already some code (this is part of the forwarding
>> strategy) that attempts to use different faces if interest is
>> retransmitted.  If an NDN router receives an interests for which there is
>> an outstanding PIT entry, and this interest is coming from the face from
>> which the router has already received an interest (with different nonce),
>> such an interest is considered a retransmission and there is an attempt to
>> forward the interest somewhere else.
>>
>> ndn::ForwardingStrategy::DetectRetransmittedInterest method defines the
>> retransmission detection logic.
>> ndn::ForwardingStrategy::CanSendOutInterest  performing some checking to
>> determine whether an interest should be forwarded on the face or not,
>> considering possible retransmission (this call is used in
>> DoPropagateInterst by the implemented forwarding strategies).
>>
>> ---
>> Alex
>>
>> On May 1, 2013, at 8:22 AM, yao hu <huyao0107 at gmail.com> wrote:
>>
>> Hi Alex,
>>
>> Thanks for your answer. I am sorry there is one more question after this.
>> How to re-send timed out interest to all faces, not retransmit it to the
>> same face again? Do I have to write my own "customConsumer", and do the
>> following
>> ndn::AppHelper consumerHelper ("customConsumer");
>> ApplicationContainer consumer = consumerHelper.Install (node);
>>
>> Am I right? Thanks a lot~
>>
>> Regards,
>> huyao
>>
>>
>>
>> 2013/4/29 Alex Afanasyev <alexander.afanasyev at ucla.edu>
>>
>>> Hi huyao,
>>>
>>> Actually, each retransmitted Interest by ndn::Consumer* application gets
>>> its own "unique" (random) nonce.
>>>
>>> Consumer::CheckRetxTimeout method (
>>> https://github.com/NDN-Routing/ndnSIM/blob/master/apps/ndn-consumer.cc#L122)
>>> is responsible for detecting and scheduling retransmission of Interest.
>>>
>>> ---
>>> Alex
>>>
>>> On Apr 28, 2013, at 7:12 PM, yao hu <huyao0107 at gmail.com> wrote:
>>>
>>> Hi Alex,
>>>
>>> Thanks for your reply. I see.
>>>
>>> One more question is about interest time out or retransmission. Is there
>>> a method or function to deal with Interest retransmission or retransmission
>>> queue in ndnsim? How about adding a new value to the nonce field in
>>> retransmission Interest packet to differentiate it from the orginal one?
>>>
>>> I assume that by default the original Interest and the retransmission
>>> Interest if timeout happens should be the same format, right?
>>>
>>> Thanks a lot ~
>>>
>>> Regards,
>>> huyao
>>>
>>>
>>>
>>> 2013/4/29 Alex Afanasyev <alexander.afanasyev at ucla.edu>
>>>
>>>> Hi huyao,
>>>>
>>>> (1) The application is fully responsible to put the nonce into the
>>>> interests. ndn::Consumer-based applications put nonce from uniform
>>>> distribution (
>>>> https://github.com/NDN-Routing/ndnSIM/blob/master/apps/ndn-consumer.cc#L206
>>>> )
>>>>
>>>> (2) There is  GetNonce() method for ndn::Interest class
>>>>
>>>> (3) If you write your own app, you just set nonce using SetNonce
>>>> method.  If you want to reuse existing consumers, then you probably need to
>>>> change their implementation to some extent.
>>>>
>>>> ---
>>>> Alex
>>>>
>>>> On Apr 28, 2013, at 7:06 AM, yao hu <huyao0107 at gmail.com> wrote:
>>>>
>>>> Hi Alex,
>>>>
>>>> ndnsim documents says nonce field is filled with a value of uint32_t
>>>> type. Could you please tell
>>>>
>>>> (1) what value is filled in nonce field in the current Interest packet
>>>> implementation.
>>>>
>>>> (2) how to get the nonce value when receiving Interest packet?
>>>>
>>>> (3) is it possible to fill a self-defined value into nonce field?
>>>>
>>>> Thanks very much!
>>>>
>>>> Regards,
>>>> huyao
>>>> _______________________________________________
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>>>> ndnSIM at lists.cs.ucla.edu
>>>> http://www.lists.cs.ucla.edu/mailman/listinfo/ndnsim
>>>>
>>>>
>>>>
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>>>
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>>
>


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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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