[Ndn-interest] Loop Detection Issue

marxer at claudio.li marxer at claudio.li
Wed Aug 3 06:50:24 PDT 2016


Sorry, last sencence should mean: "I think that loop detection might be 
partially broken..."

On 08/03/16 15:43, marxer at claudio.li wrote:
> 
> On 08/03/16 14:28, Lan Wang (lanwang) wrote:
>> They have different nonces but if the PIT entry created by C1 has not
>> been removed, then C2 may be suppressed.   This is the dangling PIT
>> entries problem.The solutions (already implemented in NFD) are the
>> following:
> 
> Yes, this is what we meant in the example.
> 
>> 
>> 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.
> 
> Yes, this works. A question regarding the implementation: According to
> the NFD developer guide, the PIT does not hold nonce values. Thus Z can
> not fully reconstruct the interest from C2. Does Z generate a new 
> nonce?
> If yes: Not sure but intuitively I think that loop partially detection
> might be broken if the green interest was also part of a loop (because 
> Z
> changes its nonce).
> 
>> 
>> Lan
> 
> Thanks to all of you for the explanations,
> Claudio
> 
>> 
>>> 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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