To calculate Network Service Level Agreements (SLAs) in ns3, we need to simulate the network for analysing the performance of the metrics defined in the. The Common SLA metrics are latency, throughput, packet loss, and availability we have to measure these metrics performance for how well the network handle these metrics. The steps given below will guide on calculating SLAs in ns3:
Step-by-step to Calculate Network SLAs in ns3
- Set Up the ns3 Environment:
- Make sure ns3 is installed.
- Define the Network Topology:
- Create a network topology with nodes and links.
- Install Applications:
- Install traffic-generating applications on the nodes to simulate network traffic.
- Define SLA Metrics:
- Define the performance metrics to be measured, such as latency, throughput, packet loss, and availability.
- Monitor Performance Metrics:
- Use trace sources or callbacks to monitor the defined metrics.
- Calculate SLA Compliance:
- Compare the measured metrics against the SLA thresholds to determine compliance.
Example Code
Here an example given to set up a simple ns3 simulation to calculate SLA compliance by measuring latency, throughput, and packet loss.
#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 (“SLAExample”);
double latencyThreshold = 50.0; // ms
double throughputThreshold = 1000.0; // kbps
double packetLossThreshold = 1.0; // percent
void CalculateSLA (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 (“Average Throughput: ” << totalThroughput << ” kbps”);
NS_LOG_UNCOND (“Average Latency: ” << averageLatency << ” ms”);
NS_LOG_UNCOND (“Packet Loss: ” << packetLoss << ” %”);
bool slaCompliant = true;
if (averageLatency > latencyThreshold)
{
NS_LOG_UNCOND (“Latency SLA violation: ” << averageLatency << ” ms exceeds ” << latencyThreshold << ” ms”);
slaCompliant = false;
}
if (totalThroughput < throughputThreshold)
{
NS_LOG_UNCOND (“Throughput SLA violation: ” << totalThroughput << ” kbps is below ” << throughputThreshold << ” kbps”);
slaCompliant = false;
}
if (packetLoss > packetLossThreshold)
{
NS_LOG_UNCOND (“Packet Loss SLA violation: ” << packetLoss << ” % exceeds ” << packetLossThreshold << ” %”);
slaCompliant = false;
}
if (slaCompliant)
{
NS_LOG_UNCOND (“SLA compliance achieved”);
}
else
{
NS_LOG_UNCOND (“SLA compliance not achieved”);
}
}
int main (int argc, char *argv[])
{
CommandLine cmd;
cmd.Parse (argc, argv);
Time::SetResolution (Time::NS);
NodeContainer nodes;
nodes.Create (2);
PointToPointHelper pointToPoint;
pointToPoint.SetDeviceAttribute (“DataRate”, StringValue (“5Mbps”));
pointToPoint.SetChannelAttribute (“Delay”, StringValue (“2ms”));
NetDeviceContainer devices;
devices = pointToPoint.Install (nodes);
InternetStackHelper stack;
stack.Install (nodes);
Ipv4AddressHelper address;
address.SetBase (“10.1.1.0”, “255.255.255.0”);
address.Assign (devices);
// Create a UDP server on node 1
UdpServerHelper server (9);
ApplicationContainer serverApp = server.Install (nodes.Get (1));
serverApp.Start (Seconds (1.0));
serverApp.Stop (Seconds (10.0));
// Create a UDP client on node 0
UdpClientHelper client (Ipv4Address (“10.1.1.1”), 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));
FlowMonitorHelper flowHelper;
Ptr<FlowMonitor> flowMonitor = flowHelper.InstallAll ();
Simulator::Stop (Seconds (11.0));
Simulator::Run ();
CalculateSLA (flowMonitor, flowHelper);
Simulator::Destroy ();
return 0;
}
Explanation
- Setup: The code sets up a simple point-to-point network between two nodes.
- Applications: A UDP server is installed on node 1, and a UDP client is installed on node 0 to generate traffic.
- Flow Monitor: The FlowMonitor is used to gather performance metrics like throughput, latency, and packet loss.
- CalculateSLA Function: This function calculates the average throughput, average latency, and packet loss, and compares them against the predefined SLA thresholds. It logs any SLA violations and indicates whether the SLA compliance is achieved.
- SLA Thresholds: The latency, throughput, and packet loss thresholds are defined at the beginning of the script.
Running the Simulation
Compile and run the simulation using the following commands in ns3 environment:
./waf configure
./waf build
./waf –run your-script-name
Replace your-script-name with the actual name of the script file.Network service level agreements in ns3 is calculated by measuring the metrics how well the network meets them is explained above detail.
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