[ndnSIM] Question about the inconsistent entry in PIT

Saran Tarnoi sarantarnoi at gmail.com
Tue Sep 10 07:22:11 PDT 2013

Dear Alex,

I was about to modify ndn-forwarding-strategy.cc and I found an ambiguous

ForwardingStrategy::OnData (from line 224,)
you put some line of codes for the case that pitEntry == 0,
where Ptr<pit::Entry> pitEntry = m_pit->Lookup (*data);.

I ran simulation in a fixed topology with ZipfMandelbrot consumer app.
Therefore, a data packet should always follow the path used by it's
interest packet.

I found that if I set the frequency of request rate to 1, there was no
single time that pitEntry = 0. Everything seemed to work as it should do.

In contrast, if the request rate was set to 10 or greater values, pitEntry
was sometimes equal to 0 at some nodes.
In other words, the considering data packet was logically unsolicited, but
in fact there should be a pending interest waiting for that data at this

I really don't understand the reason behind this case.
I have checked the PIT's size of those nodes, it was either 0 or 1, so it
did not seem to be the problem of PIT size.
I attached my scenario and topology file to this email.
If you have some time, please help me explain this.

Thanks so much for your help.

Saran Tarnoi
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