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Basically, we saw a large jump in ndnping results between two nodes even though there was no path change for the path between those two nodes. We found that it was because those nodes (or the intermediate ones) were busy updating their FIB (for other routes)
-- each registration and unregistration of a route obviously took ~10ms for NRD/NFD to process.
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<div>We were interested in RTT changes due to route changes, so the extra delay caused by the route registrations is an undesirable side effect we'd like to remove (thus Vince's email). So any suggestions on how to deal with this in our experiments are highly
appreciated.</div>
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<div>In the long term, we do need to address the problem of high processing delays of route registrations.</div>
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Lan</div>
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<div>On Apr 23, 2015, at 6:15 PM, Vince Lehman (vslehman) <<a href="mailto:vslehman@memphis.edu">vslehman@memphis.edu</a>> wrote:</div>
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Hi all,
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<div class="">I was looking over some of our hyperbolic routing results and noticed some substantial delays in ndnping when RIB registration commands are sent to the forwarder.</div>
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<div class="">Our tests use ndnping to track the RTTs between routers and when a node fails, the routing converges and new routes are registered with NFD.</div>
<div class="">What I saw in the logs was that even with our link-state routing implementation, two nodes that are directly connected were experiencing additional delay even though</div>
<div class="">their direct path was unaffected by the failed node.</div>
<div class=""><br class="">
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<div class="">I am able to replicate this result on my laptop from the command line. When I run an ndnping server and ndnping on my laptop, I see consistent RTTs. But, when I send</div>
<div class="">nfdc register commands at a relatively slow interval (0.5 s) at the same time, I see a large jump in the RTT.</div>
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<div class="">Below is an example. I started the RIB registrations right after the ping with reference 810245465.</div>
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Content From /ndn - Ping Reference = 810245457 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.307 ms<br class="">
Content From /ndn - Ping Reference = 810245458 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.296 ms<br class="">
Content From /ndn - Ping Reference = 810245459 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.229 ms<br class="">
Content From /ndn - Ping Reference = 810245460 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.291 ms<br class="">
Content From /ndn - Ping Reference = 810245461 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.155 ms<br class="">
Content From /ndn - Ping Reference = 810245462 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.251 ms<br class="">
Content From /ndn - Ping Reference = 810245463 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.271 ms<br class="">
Content From /ndn - Ping Reference = 810245464 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.436 ms<br class="">
Content From /ndn - Ping Reference = 810245465 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.328 ms<br class="">
Content From /ndn - Ping Reference = 810245466 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.22 ms<br class="">
Content From /ndn - Ping Reference = 810245467 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 14.618 ms<br class="">
Content From /ndn - Ping Reference = 810245468 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.255 ms<br class="">
Content From /ndn - Ping Reference = 810245469 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.211 ms<br class="">
Content From /ndn - Ping Reference = 810245470 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 0.854 ms<br class="">
Content From /ndn - Ping Reference = 810245471 <span class="Apple-tab-span" style="white-space:pre">
</span>- Round Trip Time = 1.274 ms<br class="">
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<div class="">I used this simple bash script to send the registration commands:</div>
<div class=""><font face="Menlo" class="">for i in `seq 1 25`; do<br class="">
nfdc register /a 258<br class="">
sleep 0.5<br class="">
done</font></div>
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<div class="">Has anyone else experienced this delay caused by registration commands? Any ideas to help reduce the RTT variance to stabilize our results?</div>
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<div class="">Any comments or suggestions you can provide would be appreciated. Thanks.</div>
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--</div>
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Vince Lehman</div>
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