Description

Lab 3: Experimenting Network Layer with NS3
Dr. Mohammad Reza Pakravan
Introduction
Routing in Fixed wired Networks
In this part we want to run a simulation to investigate the routing algorithm in the following topology. The topology is the same as the example, the sink tree of which is calculated in the class based on Dijkstra’s shortest path algorithm.

Figure 1: Network Topology
Initialization
As the rst step you have to include the modules you need as follows:
#include “ns3/core-module.h”
#include “ns3/network-module.h”
#include “ns3/internet-module.h”
#include “ns3/point-to-point-module.h”
#include “ns3/netanim-module.h”
#include “ns3/applications-module.h”
#include “ns3/animation-interface.h”
#include “ns3/point-to-point-layout-module.h”
#include “ns3/ipv4-static-routing-helper.h” #include “ns3/ipv4-list-routing-helper.h”
#include “ns3/ipv4-global-routing-helper.h”
#include “ns3/flow-monitor.h”
#include “ns3/flow-monitor-helper.h”
#include “ns3/flow-monitor-module.h”
#include <iostream>
#include <fstream>
#include <vector>
#include <string>
The next line enables you in showing some messages while running the code:
NS_LOG_COMPONENT_DEFINE (“Lab3_part1”);
At the beginning of the main function, you should declare some parameters for your simulation as follows:
uint32_t PacketSize = 512; // bytes std::string DataRate (“1Mbps”); uint16_t num_Nodes = 9; uint16_t UDPport = 9; bool tracing = false;
CommandLine object allows the user to override any of the defaults, including the above parameters, at run-time:
CommandLine cmd; cmd.AddValue (“PacketSize”, “size of application packet sent”, PacketSize); cmd.AddValue (“DataRate”, “rate of pacekts sent”, DataRate); cmd.AddValue (“tracing”, “turn on ascii and pcap tracing”, tracing); cmd.Parse (argc, argv);
The following lines override the default values of the OnO Application application used in data generation:
Config::SetDefault (“ns3::OnOffApplication::PacketSize”, UintegerValue(PacketSize));
Config::SetDefault (“ns3::OnOffApplication::DataRate”, StringValue (DataRate));
Config::SetDefault (“ns3::Ipv4GlobalRouting::RespondToInterfaceEvents”,BooleanValue(true));
Finally, you should enable Packet Meta data for animator and the name of le for animation output:
ns3::PacketMetadata::Enable(); std::string animFile = “lab3_part1.xml” ;
Network Topology
In the next step, you have to create the network topology. Network nodes are stored in a container class called NodeContainer.
NodeContainer nodes; nodes.Create (num_Nodes);
Now, you should group nodes to make links between them.
NodeContainer AB = NodeContainer (nodes.Get (0), nodes.Get (1));
NodeContainer BC = NodeContainer (nodes.Get (1), nodes.Get (2));
NodeContainer CD = NodeContainer (nodes.Get (2), nodes.Get (3));
NodeContainer DE = NodeContainer (nodes.Get (3), nodes.Get (4));
NodeContainer EF = NodeContainer (nodes.Get (4), nodes.Get (5));
NodeContainer FG = NodeContainer (nodes.Get (5), nodes.Get (6));
NodeContainer GH = NodeContainer (nodes.Get (6), nodes.Get (7));
NodeContainer HA = NodeContainer (nodes.Get (7), nodes.Get (0));
NodeContainer BH = NodeContainer (nodes.Get (1), nodes.Get (7));
NodeContainer DF = NodeContainer (nodes.Get (3), nodes.Get (5));
NodeContainer BI = NodeContainer (nodes.Get (1), nodes.Get (8));
NodeContainer CI = NodeContainer (nodes.Get (2), nodes.Get (8));
NodeContainer DI = NodeContainer (nodes.Get (3), nodes.Get (8));
NodeContainer FI = NodeContainer (nodes.Get (5), nodes.Get (8));
NodeContainer GI = NodeContainer (nodes.Get (6), nodes.Get (8));
NodeContainer HI = NodeContainer (nodes.Get (7), nodes.Get (8));
Now you should assign bandwidth and delay to each link.
PointToPointHelper p2p; p2p.SetDeviceAttribute (“DataRate”, StringValue (“1Mbps”)); p2p.SetChannelAttribute (“Delay”, StringValue (“10ms”)); NetDeviceContainer dAB = p2p.Install (AB); Do it for other links with the values like link AB.
Network Layer Parameters
In this part, you will con gure the network parameters. First, you have to install IPv4 on the network via using InternetStackHelper. This helper uses static routing as its rst priority algorithm for routing; therefore, we rede ne the priority:
NS_LOG_INFO(“Setting routing protocols”); Ipv4StaticRoutingHelper staticRouting;
Ipv4GlobalRoutingHelper globalRouting; Ipv4ListRoutingHelper list; list.Add(staticRouting,0); list.Add(globalRouting,10); // Install network stacks on the nodes InternetStackHelper internet; internet.SetRoutingHelper(list); internet.Install(nodes);
Now, you should assign IP to each node for routing and also assign the metric of each link to it.
Ipv4AddressHelper ipv4;
ipv4.SetBase (“10.1.1.0”, “255.255.255.0”); Ipv4InterfaceContainer iAB = ipv4.Assign (dAB); iAB.SetMetric(0,6); iAB.SetMetric(1,6);
ipv4.SetBase (“10.1.2.0”, “255.255.255.0”); Ipv4InterfaceContainer iBC = ipv4.Assign (dBC); iBC.SetMetric(0,3); iBC.SetMetric(1,3);
ipv4.SetBase (“10.1.3.0”, “255.255.255.0”); Ipv4InterfaceContainer iCD = ipv4.Assign (dCD); iCD.SetMetric(0,6); iCD.SetMetric(1,6);
ipv4.SetBase (“10.1.4.0”, “255.255.255.0”); Ipv4InterfaceContainer iDE = ipv4.Assign (dDE); iDE.SetMetric(0,2); iDE.SetMetric(1,2);
ipv4.SetBase (“10.1.5.0”, “255.255.255.0”); Ipv4InterfaceContainer iEF = ipv4.Assign (dEF); iEF.SetMetric(0,3); iEF.SetMetric(1,3);
ipv4.SetBase (“10.1.6.0”, “255.255.255.0”); Ipv4InterfaceContainer iFG = ipv4.Assign (dFG); iFG.SetMetric(0,2); iFG.SetMetric(1,2);
ipv4.SetBase (“10.1.7.0”, “255.255.255.0”); Ipv4InterfaceContainer iGH = ipv4.Assign (dGH); iGH.SetMetric(0,5); iGH.SetMetric(1,5);
ipv4.SetBase (“10.1.8.0”, “255.255.255.0”); Ipv4InterfaceContainer iHA = ipv4.Assign (dHA); iHA.SetMetric(0,2); iHA.SetMetric(1,2);
ipv4.SetBase (“10.1.9.0”, “255.255.255.0”); Ipv4InterfaceContainer iBH = ipv4.Assign (dBH); iBH.SetMetric(0 ,7); iBH.SetMetric(1,7);
ipv4.SetBase (“10.1.10.0”, “255.255.255.0”); Ipv4InterfaceContainer iDF = ipv4.Assign (dDF); iDF.SetMetric(0,1); iDF.SetMetric(1,1);
ipv4.SetBase (“10.1.11.0”, “255.255.255.0”); Ipv4InterfaceContainer iBI = ipv4.Assign (dBI); iBI.SetMetric(0,1); iBI.SetMetric(1,1);
ipv4.SetBase (“10.1.12.0”, “255.255.255.0”); Ipv4InterfaceContainer iCI = ipv4.Assign (dCI); iCI.SetMetric(0,5);
iCI.SetMetric(1,5);
ipv4.SetBase (“10.1.13.0”, “255.255.255.0”); Ipv4InterfaceContainer iDI = ipv4.Assign (dDI); iDI.SetMetric(0,4); iDI.SetMetric(1,4);
ipv4.SetBase (“10.1.14.0”, “255.255.255.0”); Ipv4InterfaceContainer iFI = ipv4.Assign (dFI); iFI.SetMetric(0,2); iFI.SetMetric(1,2);
ipv4.SetBase (“10.1.15.0”, “255.255.255.0”); Ipv4InterfaceContainer iGI = ipv4.Assign (dGI); iGI.SetMetric(0,1); iGI.SetMetric(1,1);
ipv4.SetBase (“10.1.16.0”, “255.255.255.0”); Ipv4InterfaceContainer iHI = ipv4.Assign (dHI); iHI.SetMetric(0,3); iHI.SetMetric(1,3);
Finally, you have to add the following code to initialize routing database and set up the routing tables in the nodes:
Ipv4GlobalRoutingHelper::PopulateRoutingTables ();
Building Flows
After doing the preceding part, now it is time to determine the application with which the nodes will function. You should install UDP application on node A and E. First, use the following code:
PacketSinkHelper UDPsink (“ns3::UdpSocketFactory”, InetSocketAddress (Ipv4Address::GetAny (), UDPport)); ApplicationContainer App;
NodeContainer SourceNode = NodeContainer (nodes.Get (0));
NodeContainer SinkNode = NodeContainer (nodes.Get (4));
To Create a UDP packet sink to receive these packets use the following codes:
App = UDPsink.Install (SinkNode);
App.Start (Seconds (0.0));
App.Stop (Seconds (10.0));
Address E_Address(InetSocketAddress(iEF.GetAddress (0), UDPport));
To Create a UDP packet source to send these packets type the following codes:
OnOffHelper UDPsource (“ns3::UdpSocketFactory”, E_Address);
UDPsource.SetAttribute (“OnTime”, StringValue (“ns3::ConstantRandomVariable[Constant=1]”));
UDPsource.SetAttribute (“OffTime”, StringValue (“ns3::ConstantRandomVariable[Constant=0]”));
UDPsource.Install(SourceNode); App.Start (Seconds (1.0));
App.Stop (Seconds (10.0));
Starting The Simulation
You should just add the following two lines to your code before running it.
Simulator::Stop(10.0); Simulator::Run();
After everything is done, you have to destroy the simulation using the following command
Simulator::Destroy();
NetAnim, Wireshark and other analysis
You should determine your nodes places for NetAnim. Do it with these codes:
AnimationInterface anim (animFile); Ptr<Node> n = nodes.Get (0); anim.SetConstantPosition (n, 0, 20); n = nodes.Get(1); anim.SetConstantPosition(n,10,10); n = nodes.Get(2); anim.SetConstantPosition(n,20,0); n = nodes.Get(3); anim.SetConstantPosition(n,30,10); n = nodes.Get(4); anim.SetConstantPosition(n,40,20); n = nodes.Get(5); anim.SetConstantPosition(n,30,30); n = nodes.Get(6); anim.SetConstantPosition(n,20,40); n = nodes.Get(7); anim.SetConstantPosition(n,10,30); n = nodes.Get(8);
anim.SetConstantPosition(n,20,20);
You can use the following code to generate the xml le used in netAnim.
if (tracing == true)
{
AsciiTraceHelper ascii; p2p.EnableAsciiAll (ascii.CreateFileStream (“Lab3_part1.tr”)); p2p.EnablePcapAll (“Lab3_part1”); }
To print routing tables you should add the following codes:
Ptr<OutputStreamWrapper> stream1 = Create<OutputStreamWrapper> (“Table1”, std::ios::out); Ipv4GlobalRoutingHelper helper2; helper2.PrintRoutingTableAllAt(Seconds(2.0),stream1);
Questions
Do the simulation and compare the result with what calculated in the class. Now change the metrics of links AB and BI to 1 and 2, respectively. Again do the simulation and investigate whether the path for sending packets from A to E has been changed or not. Change the metric of link AH to this number:
jTwo last digits of your student numberk
+3, for example if your student number is 88223987, the metric of link
AB will be: . Again do the simulation and nd the path by means of which A sends its packets to E.
Now, we want to evaluate the algorithm when a node sets down. We can make a node set down by these codes (You have to set down the links connected to this node):
Ptr<Node> node1=nodes.Get(8);
Ptr<Ipv4> ipv41=node1->GetObject<Ipv4>();
Simulator::Schedule(Seconds(3),&Ipv4::SetDown,ipv41,1);
Simulator::Schedule(Seconds(3),&Ipv4::SetDown,ipv41,2);
Simulator::Schedule(Seconds(3),&Ipv4::SetDown,ipv41,3);
Simulator::Schedule(Seconds(3),&Ipv4::SetDown,ipv41,4);
Simulator::Schedule(Seconds(3),&Ipv4::SetDown,ipv41,5);
Simulator::Schedule(Seconds(3),&Ipv4::SetDown,ipv41,6);
And to check the routing tables you can print the routing tables after this alternation by the following codes:
Ptr<OutputStreamWrapper> stream2 = Create<OutputStreamWrapper> (“Table2”, std::ios::out); helper2.PrintRoutingTableAllAt(Seconds(4.0),stream2);
Now check the tables to nd the new sink tree after the alternation. You can use NetAnim to see the routing process easily.
In all above parts, you should take some snapshots from NetAnim to compare the results obtained by simulation with what you calculate manually by the method mentioned in the class.
What Should I Do?
You must upload anything that you’ve been asked to upload and you should also answer the questions in your report. Your report should be complete and you should fully explain the API that you have used in your code. Make a folder for each section and put code and output les of each section in its corresponding folder. Compress all les and rename the compressed le to STUDENT_ID_LAB3.zip.
If you have any questions regarding the problem statement or understanding the concept, feel free to ask in cw forum.