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<p>Okay, so I performed a new experiment (i.e. just ran minindn and quit after some time) with FibManager and Forwarder DEBUG logs.</p>
<p><br>
</p>
<p>In this experiment, looked at the first Duplicate NACK on localhop prefix (Nonce:
<span>567161547</span>) and found the following:</p>
<p>1) b->a</p>
<p>2) b->c<br>
</p>
<p>3) a->c</p>
<p>4) c sends Duplicate NACK</p>
<p><br>
</p>
<p>This happens around <span>1467225861</span> - I don't see any FibManager messages around this time in NFD logs.</p>
<p><br>
</p>
<p>I have attached a sync interest trail where I grepped for the particular sync interest such as:</p>
<p><span>grep "/localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce" */ndndump* | sort -t: -nk2 | awk '{split($NF,a,"Nonce="); $NF=""; print $0 " " a[2]}' > sync-interest-trail</span></p>
<p><br>
</p>
<p>(ndndump* includes localhost as well as interface)<br>
</p>
<p><br>
</p>
<p>Seems like before the NACK, a sends interests with two different Nonces - one to c (which resulted in the above NACK), one to b (resulted in another NACK).
<br>
</p>
<p>This time I didn't see any local new interest for the sync on a (which should be equivalent to b from the previous example).<br>
</p>
<p><br>
</p>
<p>Ashlesh<br>
</p>
</div>
<hr style="display:inline-block;width:98%" tabindex="-1">
<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Junxiao Shi <shijunxiao@email.arizona.edu><br>
<b>Sent:</b> Wednesday, June 29, 2016 11:54:37 AM<br>
<b>To:</b> Ashlesh Gawande (agawande)<br>
<b>Cc:</b> Lan Wang (lanwang); nfd-dev@lists.cs.ucla.edu<br>
<b>Subject:</b> Re: [Nfd-dev] Help needed with debugging duplicate Nonce</font>
<div> </div>
</div>
<div>
<div class="">Hi Ashlesh</div>
<div class=""><br class="">
</div>
<div class="">As discussed in 20160628 NFD call, packet timing at B is like:</div>
<div class="">
<ol class="MailOutline">
<li class="">fwB receives Interest from appB with nonceB; this Interest is not forwarded</li><li class="">fwB receives Interest from fwC with nonceC</li><li class="">Interest is forwarded to fwA with nonceC</li></ol>
</div>
<div class=""><br class="">
</div>
<div class="">This exposes a weakness in outgoing Interest pipeline “pick Interest” step: when fwB forwards the Interest, it picks the latest incoming Interest with nonceC, and thus trigger Nack-Duplicate from fwA. If it picks nonceB instead, there wouldn’t
be a Nack-Duplicate from fwA.</div>
<div class=""><br class="">
</div>
<div class="">But another question is: why fwB did not forward the Interest from appB in the first place? This indicates there might be a FIB update during this process.</div>
<div class="">Can you provide NFD logs to show whether a FIB update occurred? Log level settings should be FibManager=DEBUG, Forwarder=DEBUG.</div>
<div class=""><br class="">
</div>
<div class="">Yours, Junxiao</div>
<br class="">
<div>
<blockquote type="cite" class="">
<div class="">On Jun 28, 2016, at 10:29 AM, Ashlesh Gawande (agawande) <<a href="mailto:agawande@memphis.edu" class="">agawande@memphis.edu</a>> wrote:</div>
<br class="Apple-interchange-newline">
<div class="">
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<div style="margin-top: 0px; margin-bottom: 0px;" class="">Confirmed that this is happening because node b has the same (sync) interest and hence forwards the interest to a resulting in a NACK.</div>
<div style="margin-top: 0px; margin-bottom: 0px;" class=""><br class="">
</div>
<div style="margin-top: 0px; margin-bottom: 0px;" class="">Ashlesh</div>
</div>
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<span style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px; float: none; display: inline !important;" class=""></span>
<div id="divRplyFwdMsg" dir="ltr" style="font-family: Helvetica; font-size: 12px; font-style: normal; font-variant-caps: normal; font-weight: normal; letter-spacing: normal; orphans: auto; text-align: start; text-indent: 0px; text-transform: none; white-space: normal; widows: auto; word-spacing: 0px; -webkit-text-stroke-width: 0px;" class="">
<font face="Calibri, sans-serif" style="font-size: 11pt;" class=""><b class="">From:</b><span class="Apple-converted-space"> </span>Nfd-dev <<a href="mailto:nfd-dev-bounces@lists.cs.ucla.edu" class="">nfd-dev-bounces@lists.cs.ucla.edu</a>> on behalf of Ashlesh
Gawande (agawande) <<a href="mailto:agawande@memphis.edu" class="">agawande@memphis.edu</a>><br class="">
<b class="">Sent:</b><span class="Apple-converted-space"> </span>Tuesday, June 28, 2016 10:48:35 AM<br class="">
<b class="">To:</b><span class="Apple-converted-space"> </span>Lan Wang (lanwang); Junxiao Shi<br class="">
<b class="">Cc:</b><span class="Apple-converted-space"> </span><a href="mailto:nfd-dev@lists.cs.ucla.edu" class="">nfd-dev@lists.cs.ucla.edu</a><br class="">
<b class="">Subject:</b><span class="Apple-converted-space"> </span>Re: [Nfd-dev] Help needed with debugging duplicate Nonce</font>
<div class=""> </div>
</div>
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<div style="margin-top: 0px; margin-bottom: 0px;" class="">Have attached proof for the said observation.</div>
<div style="margin-top: 0px; margin-bottom: 0px;" class=""><br class="">
</div>
<p style="margin-top: 0px; margin-bottom: 0px;" class=""></p>
<div class="">tmp-localhost_6_27$ grep --color=always 927845950 */ndndump* | sort -t: -k2<br class="">
c/ndndump.c-eth0_1.0.0.10.pcap:1467054254.052399 From: 1.0.0.10, To: 1.0.0.9, Tunnel Type: UDP, INTEREST: /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950<br class="">
b/ndndump.b-eth1_1.0.0.9.pcap:1467054254.052424 From: 1.0.0.10, To: 1.0.0.9, Tunnel Type: UDP, INTEREST: /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950<br class="">
c/ndndump.c-eth1_1.0.0.6.pcap:1467054254.052428 From: 1.0.0.6, To: 1.0.0.5, Tunnel Type: UDP, INTEREST: /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950<br class="">
a/ndndump.a-eth1_1.0.0.5.pcap:1467054254.052436 From: 1.0.0.6, To: 1.0.0.5, Tunnel Type: UDP, INTEREST: /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950<br class="">
b/ndndump.b-eth0_1.0.0.2.pcap:1467054257.955331 From: 1.0.0.2, To: 1.0.0.1, Tunnel Type: UDP, INTEREST: /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950<br class="">
a/ndndump.a-eth0_1.0.0.1.pcap:1467054257.955348 From: 1.0.0.2, To: 1.0.0.1, Tunnel Type: UDP, INTEREST: /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950<br class="">
a/ndndump.a-eth0_1.0.0.1.pcap:1467054257.965760 From: 1.0.0.1, To: 1.0.0.2, Tunnel Type: UDP, NACK: Duplicate, /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950<br class="">
b/ndndump.b-eth0_1.0.0.2.pcap:1467054257.965760 From: 1.0.0.1, To: 1.0.0.2, Tunnel Type: UDP, NACK: Duplicate, /localhop/NLSR/sync/e4c858598a526f7f25d42f4da49cb51b7950cf352e26d5092bd35126b509101b?ndn.MustBeFresh=1&ndn.Nonce=927845950<br class="">
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</div>
<div style="margin-top: 0px; margin-bottom: 0px;" class="">1) c to b</div>
<div style="margin-top: 0px; margin-bottom: 0px;" class="">2) c to a<br class="">
</div>
<div style="margin-top: 0px; margin-bottom: 0px;" class="">3) b to a<br class="">
</div>
<div style="margin-top: 0px; margin-bottom: 0px;" class="">4) a responds with duplicate NACK<br class="">
</div>
<br class="">
<div style="margin-top: 0px; margin-bottom: 0px;" class="">Meanwhile I will also try to test Junxiao's suggestion by forcing communication over TCP and make sure that this is because of local sync expressing the same interest.<br class="">
</div>
<br class="">
Ashlesh<br class="">
</div>
</div>
</div>
</blockquote>
</div>
<br class="">
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