[ndnSIM] Inconsistent number of sent packets

Fri Apr 19 08:16:22 PDT 2013

Hi Alex,

"Tx Packets" is from the "interface statistics" (right click the node from
the ns3 visualizer) of the node0 which is the data requester in this grid
scenario. Just now I tried it again by setting interest frequency as 100
(for 20 seconds), still the "Tx Packets" is 1805 (interface 0) and 22
(interface 1). The missing "Tx Packets" (around 200) are from the interest
retransmission? I also used the L3RateTracer following your instruction (as
follows).  The "PacketRaw" column of
20 Node0 2 dev=local(2) InInterests
refers the number of outgoing interest packets? Then what is the difference
between this "2000" and that "1805"?

Thanks very much for your time!

Time Node FaceId FaceDescr Type Packets Kilobytes PacketRaw KilobytesRaw
20 Node0 0 dev[0]=net(0,0-1) InInterests 0 0 0 0
20 Node0 0 dev[0]=net(0,0-1) OutInterests 0 0 0 0
20 Node0 0 dev[0]=net(0,0-1) DropInterests 0 0 0 0
20 Node0 0 dev[0]=net(0,0-1) InNacks 0 0 0 0
20 Node0 0 dev[0]=net(0,0-1) OutNacks 0 0 0 0
20 Node0 0 dev[0]=net(0,0-1) DropNacks 0 0 0 0
20 Node0 0 dev[0]=net(0,0-1) InData 71.72 74.0581 1793 1851.45
20 Node0 0 dev[0]=net(0,0-1) OutData 0 0 0 0
20 Node0 0 dev[0]=net(0,0-1) DropData 0.12 0.12375 3 3.09375
20 Node0 1 dev[0]=net(1,0-3) InInterests 0.04 0.00105469 1 0.0263672
20 Node0 1 dev[0]=net(1,0-3) OutInterests 0 0 0 0
20 Node0 1 dev[0]=net(1,0-3) DropInterests 0.04 0.00105469 1 0.0263672
20 Node0 1 dev[0]=net(1,0-3) InNacks 0 0 0 0
20 Node0 1 dev[0]=net(1,0-3) OutNacks 0 0 0 0
20 Node0 1 dev[0]=net(1,0-3) DropNacks 0 0 0 0
20 Node0 1 dev[0]=net(1,0-3) InData 0.84 0.865859 21 21.6465
20 Node0 1 dev[0]=net(1,0-3) OutData 0.04 0.0412891 1 1.03223
20 Node0 1 dev[0]=net(1,0-3) DropData 0.72 0.742109 18 18.5527
20 Node0 2 dev=local(2) InInterests 80 2.12891 2000 53.2227
20 Node0 2 dev=local(2) OutInterests 0 0 0 0
20 Node0 2 dev=local(2) DropInterests 0.2 0.00507813 5 0.126953
20 Node0 2 dev=local(2) InNacks 0 0 0 0
20 Node0 2 dev=local(2) OutNacks 0 0 0 0
20 Node0 2 dev=local(2) DropNacks 0 0 0 0
20 Node0 2 dev=local(2) InData 0 0 0 0
20 Node0 2 dev=local(2) OutData 71.72 74.0581 1793 1851.45
20 Node0 2 dev=local(2) DropData 0 0 0 0

2013/4/19 Alex Afanasyev <alexander.afanasyev at ucla.edu>

> Hi huyao,
>
> Hmm.  I just run ndn-grid scenario with frequency 10, 100, and 1000 and in
> all of the cases I see that the consumer send out exactly the theoretical
> amount of interests within 20 seconds (200, 2000, and 20000), though the
> same consumer has received different number of Data packets back due to
> buffer overflows (199, 1989, 2342).
>
> How exactly did you measure number of Interests and I'm not very sure what
> is "Tx Packets" you were referring to?  I obtained my data
> using ndn::L3RateTracer.  I put the following before Simulation::Run() in
> ndn-grid scenario (assuming the total simulation time is 20 seconds):
>
> boost::tuple< boost::shared_ptr<std::ostream>,
> std::list<Ptr<ndn::L3RateTracer> > >
>     rateTracers = ndn::L3RateTracer::InstallAll ("rate-trace.txt", Seconds
> (19.99999999));
>
> (don't forget to include the header file:
> #include <ns3/ndnSIM/utils/tracers/ndn-l3-rate-tracer.h>
> )
>
> ---
> Alex
>
> On Apr 18, 2013, at 7:07 AM, yao hu <huyao0107 at gmail.com> wrote:
>
> Hi Alex,
>
> The scenario I tested in is just the 9-node grid topology. I think maybe
> it has something wrong with my modified algorithm, since it shows no
> problem with a certain interest frequency, while with larger interest
> frequency (generally speaking) , the missing interest packets become
> obvious. I will check it soon. Thanks for your reply about routingCost. I
> see. :)
>
> Regards,
> huyao
>
>
>
> 2013/4/18 Alex Afanasyev <alexander.afanasyev at ucla.edu>
>
>> Can you send out scenario (or link to scenario), so I can try to debug
>> the problem on my machine?
>>
>> routingCost is basically an aggregated cost for the specific path.  If
>> you're using globalRoutingController, it sums up all the specified metrics
>> on the path.  For example, if you have this topology
>>
>> node1 ------ node2 ------- node3 ------- node4
>>
>> and all metrics for each link is 10, then routing cost on node1 to
>> forward towards node4 using the only available face would be 30.
>>
>> If you are using "EnableDefaultRoute" in ndn::StackHelper, then this
>> value doesn't really mean anything and suggests only that this "default" is
>> the least preferred option to forward interests.
>>
>> ---
>> Alex
>>
>> On Apr 17, 2013, at 8:36 AM, yao hu <huyao0107 at gmail.com> wrote:
>>
>> Hi Alex,
>>
>> I did not specify any randomization using Randomize parameter. I am not
>> sure whether all the interests are consumed at the first attempt, but if
>> that is a reason, the retransmitted Interest packets are not counted into
>> "Tx Packets"? Besides, I am not sure about the meaning of routingCost
>> column (2147483647) in FIB. Does it has something different from the
>> 'metric' which affects the forwarding strategy to select the BestRoute?
>> Could I specify it somewhere?
>>
>> Sorry for many questions. Thanks very much!
>>
>> Regards,
>> huyao
>>
>>
>>
>> 2013/4/17 Alex Afanasyev <alexander.afanasyev at ucla.edu>
>>
>>> Hi huyao,
>>>
>>> Did you specify any randomization for inter-interest gap using Randomize
>>> parameter (uniform, exponential)?  Though, by default there is no
>>> randomization.
>>>
>>> Btw. Do all your interest are getting satisfied from the first attempt?
>>>  If not, the difference can come from the interest retransmission, since
>>> those that needs to be retransmitted are sharing the same "cbr" constraints
>>> as new interests.
>>>
>>> ---
>>> Alex
>>>
>>> On Apr 16, 2013, at 8:32 AM, yao hu <huyao0107 at gmail.com> wrote:
>>>
>>> > Hi Alex,
>>> >
>>> > Just now, in order to verify my modification I used CustomerCbr to
>>> produce a certain number of Interest from a specific consumer, however, I
>>> found that there is a little difference between expectation and simulation
>>> result. For example, I set the Interest frequency as 10 (packets per
>>> second) for 20 seconds, the result is the number of sent packets is 200
>>> which is the same as theoretic value. But if I set the Interest frequency
>>> as 100 for 20 seconds, the simulation result is the number of sent packets
>>> is 1805 which is less than the theoretic value 2000. What is the possible
>>> reason for this phenomenon? (No packets are sent from other faces)
>>> >
>>> > Thanks for your reply!
>>> >
>>> > Regards,
>>> > huyao
>>> > _______________________________________________
>>> > ndnSIM mailing list
>>> > ndnSIM at lists.cs.ucla.edu
>>> > http://www.lists.cs.ucla.edu/mailman/listinfo/ndnsim
>>>
>>>
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>>
>
>
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