[Nfd-dev] delay with ndnpingserver

[Junxiao Shi]

Hi Obaid

This is what I have from ndn6.tk <http://yoursunny.com/p/ndn6/> to UCLA:
--- 2607:f010:3f9::11:0 ping statistics ---
20 packets transmitted, 20 received, 0% packet loss, time 19019ms
rtt min/avg/max/mdev = 141.671/142.007/143.969/0.672 ms

===  Ping Statistics For /ndn/edu/ucla ===
Sent=20, Received=20, Packet Loss=0%, Total Time=3115.14 ms
Round Trip Time (Min/Max/Avg/MDev) = (150.608/186.74/155.757/7.46211) ms

On average, ndnping is 12ms slower than ICMP ping. A few factors contribute
to this fact:

   - kernel vs userspace
      - ICMP ping is responded by OS kernel.
      - ndnping is handled by at least two userspace processes on each end.
   - signing
      - ICMP ping reply is a simple unsigned packet.
      - ndnpingserver needs to sign the reply Data with RSA. Signing is slow
      <http://redmine.named-data.net/issues/1589>, and we can't switch
      <http://redmine.named-data.net/issues/1851> to SHA256 digest now.
   - caching
      - ICMP ping reply is not cached.
      - NFD has in-network cache. ContentStore implementation is inefficient
      <http://redmine.named-data.net/issues/1706>.

ndnping variance is 7ms higher than ICMP ping, especially on the first
request. This is mainly due to the behavior of NCC strategy.

Yours, Junxiao


On Tue, Aug 26, 2014 at 11:51 PM, Syed Obaid Amin <obaidasyed at gmail.com>
wrote:

> Hello All,
>
> I am observing that ndnping is taking much time in processing the packets.
>  For e.g. have a look at the following traces. There is approx 100ms
> difference between a regular ping and ndnping (besides the first packet).
>
> oamin at arizona:~/exp-caidatopo-nfd/scripts$ ping memphis
> PING memphis-lan0 (10.1.1.5) 56(84) bytes of data.
> 64 bytes from memphis-lan0 (10.1.1.5): icmp_req=1 ttl=64 time=65.7 ms
> 64 bytes from memphis-lan0 (10.1.1.5): icmp_req=2 ttl=64 time=64.8 ms
> 64 bytes from memphis-lan0 (10.1.1.5): icmp_req=3 ttl=64 time=65.4 ms
> 64 bytes from memphis-lan0 (10.1.1.5): icmp_req=4 ttl=64 time=67.6 ms
> 64 bytes from memphis-lan0 (10.1.1.5): icmp_req=5 ttl=64 time=67.9 ms
> 64 bytes from memphis-lan0 (10.1.1.5): icmp_req=6 ttl=64 time=69.0 ms
>
> oamin at arizona:~/exp-caidatopo-nfd/scripts$ ndnping /ndn/memphis/name1
>
> === Pinging /ndn/memphis/name1 ===
>
> Content From /ndn/memphis/name1 - Ping Reference = 1260650668   - Round
> Trip Time = 232.614 ms
> Content From /ndn/memphis/name1 - Ping Reference = 1260650669   - Round
> Trip Time = 150.735 ms
> Content From /ndn/memphis/name1 - Ping Reference = 1260650670   - Round
> Trip Time = 151.064 ms
> Content From /ndn/memphis/name1 - Ping Reference = 1260650671   - Round
> Trip Time = 147.209 ms
> Content From /ndn/memphis/name1 - Ping Reference = 1260650672   - Round
> Trip Time = 151.125 ms
> Content From /ndn/memphis/name1 - Ping Reference = 1260650673   - Round
> Trip Time = 161.333 ms
>
> I checked the logs and it looks like sometime ndnpingserver after
> receiving an Interest takes much time to generate a response back.
>
> Secondly, the RTT in ndnping seems to have high variance. For e.g. look at
> the 1st and 4th packet.
>
> Any idea what's going on here? @John, are you experiencing the same?
>
> Regards,
> Obaid
>
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