[ndnSIM] Sending extra interest to just neighbor nodes

[Kanin Assantachai]

Dear Alex / Spyridon,

Hopefully you are not too busy at this time. I just discovered that the 
code I used to create extra interest for the same content to be sent to 
neighbor nodes did not work as expected. Originally after the 
PropagateInterest (inFace, interest, pitEntry); code of OnInterest 
function of ndn-forwarding-strategy.cc, I added these lines with the 
hope to send another interest for the same content, but with different 
scope and outgoing face:

interest->SetScope (2);
pitEntry->ClearOutgoing ();
pitEntry->AddOutgoing (<another_out_face>);
PropagateInterest (inFace, interest, pitEntry);

However after this part of code is called, the second call to 
PropagateInterest function (the last line that I added) detects that it 
is a retransmission of interest instead, and I get the -SIGIOT error. (I 
checked the isRetransmitted boolean value in the PropagateInterest 
function and found this error)

To fix this, I first thought about creating another pitEntry requesting 
the same content, but with the new outgoing face and interest scope. 
However, I believe this is not possible because PIT table should not 
contain multiple entries for the same content request.

Then I thought about modifying the existing pitEntry for that particular 
content by adding another outgoing face to its list of outgoing face. 
However, I am not sure what the simulator will behave when it finds 
multiple outgoing faces in its list. Will the node send interests to all 
possible faces in the list of outgoing faces? Also by using this method, 
the PropagateInterest function will be called only once to send 
interests with different scopes. If this is the correct approach, how 
can I set different scopes for interests which are to be forwarded to 
different outgoing faces?

Or if you can suggest other approaches, I will gladly follow those 
suggestions as well. Your kind help is appreciated.

Kanin Assantachai