[ndnSIM] question about faceIterator in CustomStrategy

[yao hu]

Hi Alex,

I understand what you mean. In ndnsim, setting forwarding strategy is
meaningless if routes are not configured. Now I have made some progress. I
am sorry for bothering you to check the following..

When setting up *default* FIB entries using
StackHelper::SetDefaultRoutes()<http://ndnsim.net/doxygen/classns3_1_1ndn_1_1_stack_helper.html#a12b1c8f16bad953ac3b9bb4a6ab1fcab>
call
that is to let each node/router have a FIB entry to / prefix, containing
all available faces. So for the prefix "/"(class Name), its size() ==
0? (pitEntry->GetFibEntry
()->m_prefix->size() == 0?)

Thanks a lot!

Regards,
huyao


2013/3/31 Alex Afanasyev <alexander.afanasyev at ucla.edu>

> Looks good.
>
> Your forwarding strategy has full control on how Interests are forwarded,
> so you're free to ignore the contents suggested faces in the FIB entry.
>
> ---
> Alex
>
> On Mar 30, 2013, at 9:34 PM, yao hu <huyao0107 at gmail.com> wrote:
>
> Hi Alex,
>
> Thanks for your reply. That means SetDefaultRoutes(true) does not
> conflict with my later implementation in ccnxHelper.SetForwardingStrategy
> ("ns3::ndn::fw::CustomStrategy")? That is, before installing stack on
> nodes, the following codes is ok?
>
>   ndn::StackHelper ccnxHelper;
>   *ccnxHelper.SetForwardingStrategy ("ns3::ndn::fw::CustomStrategy");*
>   *ccnxHelper.SetDefaultRoutes (true);*
>   ccnxHelper.SetContentStore ("ns3::ndn::cs::Lru",
>                               "MaxSize", "1"); // ! Attention ! If set to
> 0, then MaxSize is infinite
>   ccnxHelper.InstallAll ();
>
> Regards,
> huyao
>
>
>
> 2013/3/31 Alex Afanasyev <alexander.afanasyev at ucla.edu>
>
>> Hi huyao,
>>
>> You still have to have an entry in FIB that corresponds to forwarded
>> interests.  This entry is part of overall logic to forward interests, data,
>> and record data performance stats for the forwarded data.
>>
>> In your case, you can have an entry that corresponds to "/" prefix.  The
>> easiest way to do it, is to use ndn::StackHelper::SetDefaultRoutes(true),
>> which will create this entry and fill with all available faces (which you
>> can ignore later).
>>
>> ---
>> Alex
>>
>> On Mar 30, 2013, at 8:33 PM, yao hu <huyao0107 at gmail.com> wrote:
>>
>> Hi Alex,
>>
>> I see. I forgot about it. Thanks for your explanation. I am sorry I have
>> one question about flooding strategy in ndnsim.
>>
>> I saw your reply
>> http://www.lists.cs.ucla.edu/pipermail/ndnsim/2012-December/000030.html that
>> mentions how to flood to all available faces not listed in FIB. Now I
>> assume that when ndnsim simulation starts, I do not manually configure FIB
>> routes by AddRoute, that is, FIB on each node is empty, and let each node
>> forward the incoming interest to all available faces and don't want them
>> to add to FIB entries by the following
>>
>> Ptr<L3Protocol> ndn = this->GetObject<L3Protocol> (); for (uint32_t
>> faceNum = 0; faceNum < ndn->GetNFaces (); faceNum++) { Ptr<Face> outFace =
>> ndn->GetFace (faceNum); TrySendOutInterest (inFace, outFace, header,
>> origPacket, pitEntry); }
>>
>> However the interest will be not forwarded from any face and it seems no
>> interest packet is produced. What is wrong with it? Thanks a lot.
>>
>> Regards,
>> huyao
>>
>>
>>
>> 2013/3/31 Alex Afanasyev <alexander.afanasyev at ucla.edu>
>>
>>> Hi huyao,
>>>
>>> The data structure that stores ordered Face instances in FIB behaves
>>> like any other STL container:
>>> begin ()  returns iterator to first element in the container
>>> end () returns a special iterator, indicating element just after the
>>> last valid element
>>>
>>> In other words, end () is never an iterator to a valid element in the
>>> container, and situations when begin () == end () means that the container
>>> has no elements.  If there is at least one element in the container, begin
>>> () will return iterator to a valid first element.
>>>
>>> ---
>>> Alex
>>>
>>> On Mar 30, 2013, at 8:20 AM, yao hu <huyao0107 at gmail.com> wrote:
>>>
>>> Hi Alex,
>>>
>>> Thanks for your reply to the previous question about ndnsim update.
>>>
>>> Now I am looking into the CustomStrategy::DoPropagateInterest. This
>>> function is to let Interest be forwarded to first two best-metric faces
>>> specified by FIB. However, in the codes, the faceIterator is first pointed
>>> to the beginning of faces ordered by metric and then checked whether it is
>>> pointed to the end of the faces. Assume that there is only one face
>>> existing in the associated faces for the fib entry. For my understanding,
>>> this face is located at the beginning of the faces and also should be
>>> located at the end of the faces. Then according to the DoPropagateInterest
>>> algorithm, the incoming interest will be not sent out though the fact is
>>> not like that for sure. So what is wrong with my understanding for the
>>> faceIterator? Or what is the internal structure of FacesByMetric &faces
>>> especially faces.begin () or faces.end()?
>>>
>>> I am sorry for my confusing expression. Thank you very much!
>>>
>>> Regards,
>>> huyao
>>> _______________________________________________
>>> ndnSIM mailing list
>>> ndnSIM at lists.cs.ucla.edu
>>> http://www.lists.cs.ucla.edu/mailman/listinfo/ndnsim
>>>
>>>
>>>
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