[ndnSIM] dealing with duplicated Interests for data provider

[Alex Afanasyev]

Hi huyao,

This is a very good question.  I completely agree that there is kind of ambiguity with what you routers-producers need to do when they receive duplicate interests and there is actually both options available in ndnSIM.   By default, ndnSIM will reply both such interests, but you can configure as well to drop the second duplicate interests.

Here is some details.  When producer receives the first interest, it will immediately satisfies it, marking PIT entry to be erased.  In default mode, the entry is immediately deleted, removing all the knowledge about previously seen nonces.  You can configure PitEntryPruningTimeout (http://ndnsim.net/doxygen/classns3_1_1ndn_1_1_pit.html#details), so this knowledge is retained for some time, effectively preventing second/third interest from being satisfied.

Which way is the right one?  I don't really have a definite answer... As you can see from the default mode, I tend to agree with you that the second Interest should be satisfied as well, but one can argue that this is kind of wasteful.

---
Alex

On Jun 17, 2013, at 9:40 AM, yao hu <huyao0107 at gmail.com> wrote:

> Hi Alex,
> 
> For intermediate routers, they drop the subsequent Interests (with the same nonce) from the same requester to avoid the loop Interest path. But if the data provider receives two identical Interests (with the same nonce) from two different faces, it will still drop the subsequent incoming Interest? How about replying the Data both on these two faces? Because I think this is still meaningful to ensure the data retrieval.  
> 
> Thanks for your reply~
> 
> Regards,
> huyao
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