[Ndn-interest] Loop Detection Issue

Lixia Zhang lixia at CS.UCLA.EDU
Wed Aug 3 05:35:19 PDT 2016


> On Aug 3, 2016, at 5:28 AM, Lan Wang (lanwang) <lanwang at memphis.edu> wrote:
> 
> They have different nonces but if the PIT entry created by C1 has not been removed, then C2 may be suppressed.

just to clarify: the original scenario described in the slide deck says that the data has been returned to C1 before C2's interest, that's what my early reply was based on.

Otherwise: yes procedure (2) below as Lan described should be followed by design.

>   This is the dangling PIT entries problem.  The solutions (already implemented in NFD) are the following:
> 
> 1. some strategies, e.g., recent versions of BestRoute) allow interest retransmission: when an interest is forwarded, a suppression timer is set on the PIT.  When the timer expires, it  may forward any new Interest matching the PIT (and then set the suppression timer again).
> 
> 2. when X detects an Interest with a duplicate nonce, it sends a duplicate NACK  which may be further forwarded to clear the dangling PIT entries at the nodes that sent the interest.  When the PIT entry is cleared, new interest with the same name can be forwarded.  Right now some strategies (not all) in NFD handle the NACKs correctly.
> 
> Lan
> 
>> On Aug 3, 2016, at 4:54 AM, Lixia Zhang <lixia at cs.ucla.edu> wrote:
>> 
>> I have a few other questions to the specifics of the scenario.
>> for a short answer quick: interests form C1 and C2 carry different nonces, so your concern on the last slide should not happen as I see.
>> 
>>> On Aug 3, 2016, at 1:15 AM, marxer at claudio.li wrote:
>>> 
>>> Hi all,
>>> 
>>> Urs and I constructed a situation in which we think the network does not behave as expected (attached PDF). Can this happen in the wild or did we oversee something?
>>> 
>>> Thanks,
>>> Urs and Claudio
>>> 
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>> 
>> 
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