How to Calculate Network Policy Enforcement in Ns3

To calculate network policy enforcement in ns3, by enforcing the policies like traffic filtering, rate limiting at various points in the network, such as routers or firewalls after setting up a network topology. The policies performance impact can be measured using metrics like throughput, latency, and packet loss.

The step-by-step given below will guide on how to simulate this enforcement in ns3.

Step-by-step to Simulate and Calculate Network Policy Enforcement in ns3

1. Set Up the NS-3 Environment:
   • Make sure ns3 is installed.
2. Define the Network Topology:
   • Create a network topology with nodes, routers, and policy enforcement points.
3. Implement Network Policies:
   • Configure network policies such as traffic filtering or rate limiting.
4. Install Applications:
   • Install traffic-generating applications on the nodes to simulate network traffic.
5. Monitor Performance Metrics:
   • Use trace sources or callbacks to monitor performance metrics such as throughput, latency, and packet loss.
6. Analyze Policy Enforcement Performance:
   • Calculate and log the performance metrics to evaluate the effectiveness of the network policies.

Example Code

The example script given below will guide to set up a simple ns3 simulation to calculate network policy enforcement performance.

#include “ns3/core-module.h”

#include “ns3/network-module.h”

#include “ns3/internet-module.h”

#include “ns3/point-to-point-module.h”

#include “ns3/applications-module.h”

#include “ns3/flow-monitor-module.h”

using namespace ns3;

NS_LOG_COMPONENT_DEFINE (“NetworkPolicyEnforcementExample”);

void PacketFilter(Ptr<const Packet> packet, Ptr<Ipv4> ipv4, uint32_t interface)

{

Ipv4Header ipv4Header;

packet->PeekHeader(ipv4Header);

Ipv4Address srcAddr = ipv4Header.GetSource();

Ipv4Address dstAddr = ipv4Header.GetDestination();

// Example policy: Drop packets from a specific IP address

if (srcAddr == Ipv4Address(“10.1.1.1”))

{

NS_LOG_UNCOND(“Packet from ” << srcAddr << ” to ” << dstAddr << ” dropped by policy”);

ipv4->Drop(packet, Ipv4L3Protocol::DROP_POLICY);

}

}

voidCalculatePolicyEnforcementPerformance(Ptr<FlowMonitor>flowMonitor, FlowMonitorHelper &flowHelper)

{

Ptr<Ipv4FlowClassifier>classifier=DynamicCast<Ipv4FlowClassifier> (flowHelper.GetClassifier ());

std::map<FlowId, FlowMonitor::FlowStats> stats = flowMonitor->GetFlowStats ();

double totalThroughput = 0.0;

double totalLatency = 0.0;

uint32_t totalPackets = 0;

uint32_t lostPackets = 0;

for (auto it = stats.begin (); it != stats.end (); ++it)

{

Ipv4FlowClassifier::FiveTuple t = classifier->FindFlow (it->first);

double throughput = it->second.rxBytes * 8.0 / (it->second.timeLastRxPacket.GetSeconds () – it->second.timeFirstTxPacket.GetSeconds ()) / 1024; // kbps

double latency = it->second.delaySum.GetSeconds () / it->second.rxPackets * 1000; // ms

uint32_t packets = it->second.rxPackets + it->second.lostPackets;

totalThroughput += throughput;

totalLatency += latency;

totalPackets += packets;

lostPackets += it->second.lostPackets;

}

double averageLatency = totalPackets > 0 ? totalLatency / stats.size () : 0;

double packetLoss = totalPackets > 0 ? (static_cast<double> (lostPackets) / totalPackets) * 100 : 0;

NS_LOG_UNCOND (“Total Throughput: ” << totalThroughput << ” kbps”);

NS_LOG_UNCOND (“Average Latency: ” << averageLatency << ” ms”);

NS_LOG_UNCOND (“Packet Loss: ” << packetLoss << ” %”);

}

int main (int argc, char *argv[])

{

CommandLine cmd;

cmd.Parse (argc, argv);

Time::SetResolution (Time::NS);

// Create nodes

NodeContainer nodes;

nodes.Create (4); // Client, Router with policy, Router, Server

// Create point-to-point links

PointToPointHelper pointToPoint;

pointToPoint.SetDeviceAttribute (“DataRate”, StringValue (“10Mbps”));

pointToPoint.SetChannelAttribute (“Delay”, StringValue (“2ms”));

NetDeviceContainer devices01 = pointToPoint.Install (NodeContainer (nodes.Get (0), nodes.Get (1)));

NetDeviceContainer devices12 = pointToPoint.Install (NodeContainer (nodes.Get (1), nodes.Get (2)));

NetDeviceContainer devices23 = pointToPoint.Install (NodeContainer (nodes.Get (2), nodes.Get (3)));

// Install the internet stack on nodes

InternetStackHelper stack;

stack.Install (nodes);

// Assign IP addresses to the devices

Ipv4AddressHelper address;

 

address.SetBase (“10.1.1.0”, “255.255.255.0”);

Ipv4InterfaceContainer interfaces01 = address.Assign (devices01);

address.SetBase (“10.1.2.0”, “255.255.255.0”);

Ipv4InterfaceContainer interfaces12 = address.Assign (devices12);

address.SetBase (“10.1.3.0”, “255.255.255.0”);

Ipv4InterfaceContainer interfaces23 = address.Assign (devices23);

// Enable routing

Ipv4GlobalRoutingHelper::PopulateRoutingTables ();

// Create UDP server on node 3 (Server)

UdpServerHelper server (9);

ApplicationContainer serverApp = server.Install (nodes.Get (3));

serverApp.Start (Seconds (1.0));

serverApp.Stop (Seconds (10.0));

// Create UDP client on node 0 (Client)

UdpClientHelper client (interfaces23.GetAddress (1), 9);

client.SetAttribute (“MaxPackets”, UintegerValue (320));

client.SetAttribute (“Interval”, TimeValue (MilliSeconds (10)));

client.SetAttribute (“PacketSize”, UintegerValue (1024));

ApplicationContainer clientApp = client.Install (nodes.Get (0));

clientApp.Start (Seconds (2.0));

clientApp.Stop (Seconds (10.0));

 

// Configure packet filter on the policy enforcement node (node 1)

Ptr<Ipv4> ipv4 = nodes.Get (1)->GetObject<Ipv4> ();

ipv4->TraceConnectWithoutContext (“Rx”, MakeCallback (&PacketFilter));

// Install flow monitor to capture performance metrics

FlowMonitorHelper flowHelper;

Ptr<FlowMonitor> flowMonitor = flowHelper.InstallAll ();

Simulator::Stop (Seconds (11.0));

Simulator::Run ();

CalculatePolicyEnforcementPerformance (flowMonitor, flowHelper);

Simulator::Destroy ();

return 0;

}

Explanation

1. Setup: The code sets up a simple network topology with four nodes: a client, a router with a policy, another router, and a server, connected by point-to-point links.
2. Internet Stack and Routing: The internet stack is installed on all nodes, and global routing is enabled.
3. Applications: A UDP server is installed on the server node (node 3), and a UDP client is installed on the client node (node 0) to generate traffic.
4. Policy Configuration: A packet filter is configured on the router with the policy (node 1) to drop packets from a specific IP address.
5. Flow Monitor: The FlowMonitor is used to gather performance metrics like throughput, latency, and packet loss.
6. CalculatePolicyEnforcementPerformance Function: This function calculates the total throughput, average latency, and packet loss, and logs these metrics to evaluate the performance impact of the network policies.

Running the Simulation

Compile and run the simulation using the following commands in your ns3 environment:

./waf configure

./waf build

./waf –run your-script-name

Replace the-script-name with the actual name of the script file.

The above example script clearly explained how to calculate performance impact of the Network policy Enforcement in ns3 which uses simple traffic filtering policy.

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