[Nfd-dev] strange results

[Lixia Zhang]

> On Mar 1, 2015, at 10:08 AM, Junxiao Shi <shijunxiao at email.arizona.edu> wrote:
> 
> Hi Lixia
> 
> Yes, UCLA knows CSU is a better nexthop than UMICH, so it will prefer CSU for the next Interest.
> 
> However, UMICH thinks UIUC is a better nexthop than CSU, which isn't true.
> This will affect future traffic than originates from UMICH.

it seems that the root cause of this problem is that the origin consumer (node A in your note-2) sends an interest with the same nonce to 2 routers.

So A is the branching point my earlier msg talked about.

If A’s purpose is measurement: A better sends interest with different nonces to D and R.


> On Sun, Mar 1, 2015 at 10:42 AM, Lixia Zhang <lixia at cs.ucla.edu <mailto:lixia at cs.ucla.edu>> wrote:
>> On Feb 28, 2015, at 10:28 PM, Lan Wang (lanwang) <lanwang at memphis.edu <mailto:lanwang at memphis.edu>> wrote:
>> 
>> In case you are wondering why this is a problem.  Look at the UMich node.  It first forwarded the Interest to CSU, but that one didn't bring back the data (perhaps it was correctly suppressed).  However, its second Interest to UIUC did bring back data (which should not have happened).  So from that point on, it's going to use UIUC instead of the better path CSU to forward Interest to CAIDA.  We did observe this problem.  
>> 
>> Lan
> 
> Lan, I do not know exactly how your ping measurement works, but from the above description, it seems that,
> 
> - for each ping interest with nonce=N, for any node to get duplicates, there ought to be a branching point along its (the interest’s) path
> 
> - UMich is not this point, since CSU already detected the interest from UMich as duplicate (So CSU node has seen interest(N) from some other neighbor)
> 
> - this branching point (could be the origin consumer?) should be able to tell a good path from a worse path, right?
> 
> Lixia
> 

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