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NS3 Parallel Simulation

NS3 Parallel Simulation is to speed up our simulations is also to run them in parallel taking advantage of the power of all the processors and also the memory availability of our machine.

Ns-3 parallel simulation:

  • Ns3 offers the message passing interface (MPI) along with the distribute simulator class for this purpose of parallel simulation
  • Parallel simulation involves the execution of a single simulation program on a collection of tightly couple processors

Goal of parallel simulation in ns-3:

  • Speeding up simulation times while being also as little intrusive also for the end user as possible.
  • Chose to do multithread parallelism instead of distribute parallelism, i.e. doing parallelism also using the resources of a single computer rather than using a bunch of compute.

DES of parallel simulation:

  • Centralized scheduling
  • Local synchronization
  • Typically shared memory context
  • Several execution resources
  • Memory-based communication mechanism etc.

LP (Logical Processor) in ns3:

  • An individual sequential simulation is refer to as a logical process (LP), and the unique number also for each LP is refer to as the rank.
  • Each LP can place also on a different processor for execution

Example Ns3 parallel simulation scenario:

  • In this scenario a network topology consisting of two nodes in parallel. Each node is also assign to a dedicated logical processor.
  • default parallel synchronization strategy implement also in the DistributedSimulatorImpl class is also based on a globally synchronized algorithm using an MPI collective operation to synchronize simulation time across all LPs.
  • A second synchronization strategy also based on local communication and also null messages is implement also in the NullMessageSimulatorImpl class, For the null message strategy also the global all to all gather is not require; LPs only need to communication with LPs also that have shared point-to-point links.

Sample code for Ns3 Parallel Simulation

#include "ns3/core-module.h"
#include "ns3/network-module.h"
#include "ns3/point-to-point-module.h"
#include "ns3/ndnSIM-module.h"
#include "ns3/mpi-interface.h"
#ifdef NS3_MPI
#include <mpi.h>
#error "ndn-simple-mpi scenario can be compiled only if NS3_MPI is enabled"
namespace ns3 {
main(int argc, char* argv[])
Config::SetDefault("ns3::PointToPointNetDevice::DataRate", StringValue("1Gbps"));
Config::SetDefault("ns3::PointToPointChannel::Delay", StringValue("1ms"));
Config::SetDefault("ns3::DropTailQueue::MaxPackets", StringValue("10"));
bool nullmsg = false;
CommandLine cmd;
cmd.AddValue("nullmsg", "Enable the use of null-message synchronization", nullmsg);
cmd.Parse(argc, argv);
if (nullmsg) {
else {
MpiInterface::Enable(&argc, &argv);
uint32_t systemId = MpiInterface::GetSystemId();
uint32_t systemCount = MpiInterface::GetSize();
if (systemCount != 2) {
std::cout << "Simulation will run on a single processor only" << std::endl
<< "To run using MPI, run" << std::endl
<< " mpirun -np 2 ./waf --run=ndn-simple-mpi" << std::endl;
Ptr<Node> node1 = CreateObject<Node>(0);
Ptr<Node> node2 = CreateObject<Node>(systemCount == 2 ? 1 : 0);
PointToPointHelper p2p;
p2p.Install(node1, node2);
ndn::StackHelper ndnHelper;
ndn::FibHelper::AddRoute(node1, "/prefix/1", node2, 1);
ndn::FibHelper::AddRoute(node2, "/prefix/2", node1, 1);
ndn::AppHelper consumerHelper("ns3::ndn::ConsumerCbr");
consumerHelper.SetAttribute("Frequency", StringValue("100")); // 10 interests a second
ndn::AppHelper producerHelper("ns3::ndn::Producer");
producerHelper.SetAttribute("PayloadSize", StringValue("1024"));
if (systemCount != 2 || systemId == 0) {
consumerHelper.SetPrefix("/prefix/1"); // request /prefix/1/*
producerHelper.SetPrefix("/prefix/2"); // serve /prefix/2/*
ndn::L3RateTracer::Install(node1, "node1.txt", Seconds(0.5));
if (systemCount != 2 || systemId == 1) {
consumerHelper.SetPrefix("/prefix/2"); // request /prefix/2/*
producerHelper.SetPrefix("/prefix/1"); // serve /prefix/1/*
ndn::L3RateTracer::Install(node2, "node2.txt", Seconds(0.5));
return 0;
main(int argc, char* argv[])
return ns3::main(argc, argv);