[ndnSIM] Inconsistent number of sent packets

yao hu huyao0107 at gmail.com
Thu Apr 18 07:07:31 PDT 2013


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
>> > _______________________________________________
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>> > ndnSIM at lists.cs.ucla.edu
>> > http://www.lists.cs.ucla.edu/mailman/listinfo/ndnsim
>>
>>
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