[ndnSIM] Question on default forwarding strategy

Alex Afanasyev alexander.afanasyev at ucla.edu
Fri Sep 12 15:59:29 PDT 2014


Hi Wenjie,

Nonce is used to detect whether the network has any loops.  If a node is receiving a similar interests (e.g., the same name) and different nonce, then it is either original requester retransmitted or somebody else in the network has expressed the same interest.  If a node is receiving exactly the same interest (same name and nonce), then network has looped back the interest.  In the latter case, the forwarding strategy can simply ignore such interest, while in the former case the strategy would remember the incoming face and will forward the data packet towards this face when/if it becomes available.

---
Alex

On Aug 22, 2014, at 11:59 AM, Wenjie Li <liwenjie at cs.QueensU.CA> wrote:

> Hi Alex,
> 
> I have a question on a piece of code about default forwarding strategy.
> It locates in ndn-forwarding-strategy.cc, OnInterest(...) function.
> 
> In the code, you check the the nonce of interest packet to check whether it is duplicated. Since in ndn-consumer.cc, you assign a different nonce to an interest packet even if it is retransmitted, I don't know the purpose of this check. It seems that the duplication will happen total randomly (according to some distribution set in consumer). How do you define such 'duplicate'.
> 
> Thank you for your help.
> 
> All the best,
> 
> Wenjie Li
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