[ndnSIM] Confusion about consumer settings

[yao930 at mail.ustc.edu.cn]

Hello all，


I am doing experiment with ndnSIM2.7 recently, and encountered some strange problems.


The topology I used has 8 nodes,whick looks like the follows: 
5
 \
  \
6---4--3--2--1--0  
  /
 /
7
Node 5,6,7 is consumer, and node 0 is producer. Bandwidth in 1-2 and 2-3 is set to be 1Mbps, and others is set to be 5Mbps. Max packet size is set to be 10 packets. Packet payload is set to be 1024.




I use 3 consumerHelper to make node 5,6,7 generate interests with different prefix, like:
 NodeContainer consumerNodes1;
  NodeContainer consumerNodes2;
  NodeContainer consumerNodes3;
  NodeContainer producerNodes;
  NodeContainer routerNodes;




  consumerNodes1.Add(Names::Find<Node>("5"));
  
  consumerNodes2.Add(Names::Find<Node>("6"));


  consumerNodes3.Add(Names::Find<Node>("7"));  


  std::string prefix1 = "/A1";  
  std::string prefix2 = "/A2";  
  std::string prefix3 = "/A3";  


  // Install NDN applications
  ndn::AppHelper consumerHelper1("ns3::ndn::ConsumerZipfMandelbrot");
  consumerHelper1.SetPrefix(prefix1);
  consumerHelper1.SetAttribute("Frequency", StringValue("100")); // 100 interests a second
  consumerHelper1.SetAttribute("NumberOfContents", StringValue("5000"));
  consumerHelper1.Install(consumerNodes1);


  ndn::AppHelper consumerHelper2("ns3::ndn::ConsumerZipfMandelbrot");
  consumerHelper2.SetPrefix(prefix2);
  consumerHelper2.SetAttribute("Frequency", StringValue("100")); // 100 interests a second
  consumerHelper2.SetAttribute("NumberOfContents", StringValue("5000"));
  consumerHelper2.Install(consumerNodes2);


  ndn::AppHelper consumerHelper3("ns3::ndn::ConsumerZipfMandelbrot");
  consumerHelper3.SetPrefix(prefix3);
  consumerHelper3.SetAttribute("Frequency", StringValue("100")); // 10 interests a second
  consumerHelper3.SetAttribute("NumberOfContents", StringValue("5000"));
  consumerHelper3.Install(consumerNodes3);


what I expected is that node5,6,7 should receive data packets equally, but the actual result is node5 receive most, and node7 receive the least. I counted the rate-trace.txt, and the result is:
A1Packet: 4460
A2Packet: 1386
A3Packet: 382
totalPacket: 6228


My questions are：
1、why the data packets received by the 3 consumer is so different?
2、I observed that in this scenario 1Mpbs bandwidth can transmit at most 120 or so，how is this result calculated? 


Thanks in advance!


Sincerely,
Chris Chen.







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