[Ndn-interest] Loop Detection Issue
marxer at claudio.li
marxer at claudio.li
Wed Aug 3 06:43:38 PDT 2016
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
>>>
>>> <interest-looping.pdf>_______________________________________________
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>>> Ndn-interest at lists.cs.ucla.edu
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>>
>>
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