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<div>On Mar 1, 2015, at 2:01 PM, Lixia Zhang <<a href="mailto:lixia@CS.UCLA.EDU">lixia@CS.UCLA.EDU</a>> wrote:</div>
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<div class="">On Mar 1, 2015, at 10:08 AM, Junxiao Shi <<a href="mailto:shijunxiao@email.arizona.edu" class="">shijunxiao@email.arizona.edu</a>> wrote:</div>
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<div dir="ltr" class="">Hi Lixia
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<div class="">Yes, UCLA knows CSU is a better nexthop than UMICH, so it will prefer CSU for the next Interest.</div>
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<div class="">However, UMICH thinks UIUC is a better nexthop than CSU, which isn't true.</div>
<div class="">This will affect future traffic than originates from UMICH.</div>
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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.</div>
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<div>So A is the branching point my earlier msg talked about.</div>
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<div>If A’s purpose is measurement: A better sends interest with different nonces to D and R.</div>
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The problem here is ineffective duplicate suppression. There's no need to use a different nonce in this case, as long as interests with duplicate nonces are detected correctly *after* a PIT is satisfied. Using a different nonce may work, but it's not required
for solving this problem.</div>
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<div>Lan<br>
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<div class="gmail_quote">On Sun, Mar 1, 2015 at 10:42 AM, Lixia Zhang <span dir="ltr" class="">
<<a href="mailto:lixia@cs.ucla.edu" target="_blank" class="">lixia@cs.ucla.edu</a>></span> wrote:
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<div class="">On Feb 28, 2015, at 10:28 PM, Lan Wang (lanwang) <<a href="mailto:lanwang@memphis.edu" target="_blank" class="">lanwang@memphis.edu</a>> wrote:</div>
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<div style="word-wrap:break-word" class="">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. <br class="">
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</span>Lan, I do not know exactly how your ping measurement works, but from the above description, it seems that,</div>
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<div class="">- 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</div>
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<div class="">- 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)</div>
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<div class="">- this branching point (could be the origin consumer?) should be able to tell a good path from a worse path, right?</div>
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<div class="">Lixia</div>
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