How to Calculate Maximum Deadline in ns3

To calculate the maximum deadline in ns3, this contains to defining the maximum acceptable time by which packets must extent with destination that look out to be delivered successfully within the restraints of real time application. It is depend on the particular necessities of the application being evaluated.

Steps to Calculate Maximum Deadline

  1. Set up the Simulation: Create a network topology with nodes and links configured to simulate the network environment.
  2. Install Applications: Use a UDP client and server application to send and receive packets.
  3. Record Packet Timestamps: Use packet tracing to record the timestamps when packets are sent and received.
  4. Calculate Deadline: Determine the time by which a packet must be received to meet the application’s deadline requirements.

Example Implementation

The given below is the sample implementation on how to setup a point-to-point network in ns3 and evaluates whether the packets meets the particular deadline:

Setting Up the Network Simulation

#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/packet.h”

#include <iostream>

using namespace ns3;

NS_LOG_COMPONENT_DEFINE(“DeadlineExample”);

class TimeTag : public Tag

{

public:

TimeTag () {}

TimeTag (Time time) : m_time (time) {}

static TypeId GetTypeId (void)

{

static TypeId tid = TypeId (“ns3::TimeTag”)

.SetParent<Tag> ()

.AddConstructor<TimeTag> ();

return tid;

}

virtual TypeId GetInstanceTypeId (void) const

{

return GetTypeId ();

}

virtual void Serialize (TagBuffer i) const

{

int64_t time = m_time.GetNanoSeconds ();

i.Write ((const uint8_t *)&time, sizeof (time));

}

virtual void Deserialize (TagBuffer i)

{

int64_t time;

i.Read ((uint8_t *)&time, sizeof (time));

m_time = NanoSeconds (time);

}

virtual uint32_t GetSerializedSize (void) const

{

return sizeof (int64_t);

}

virtual void Print (std::ostream &os) const

{

os << “t=” << m_time;

}

void SetTime (Time time)

{

m_time = time;

}

Time GetTime (void) const

{

return m_time;

}

private:

Time m_time;

};

void

PacketSentCallback(Ptr<const Packet> packet)

{

TimeTag tag (Simulator::Now ());

const_cast<Packet *>(packet)->AddByteTag (tag);

}

void

PacketReceivedCallback(Ptr<const Packet> packet)

{

TimeTag tag;

bool found = packet->FindFirstMatchingByteTag (tag);

if (found)

{

Time sendTime = tag.GetTime ();

Time receiveTime = Simulator::Now ();

Time delay = receiveTime – sendTime;

Time deadline = MilliSeconds (100); // Example deadline of 100 milliseconds

if (delay <= deadline)

{

std::cout << “Packet received within deadline: ” << delay.GetMilliSeconds () << ” ms” << std::endl;

}

else

{

std::cout << “Packet missed deadline: ” << delay.GetMilliSeconds () << ” ms” << std::endl;

}

}

}

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

{

Time::SetResolution(Time::NS);

LogComponentEnable(“DeadlineExample”, LOG_LEVEL_INFO);

// Create nodes

NodeContainer nodes;

nodes.Create(2);

// Set up point-to-point link

PointToPointHelper pointToPoint;

pointToPoint.SetDeviceAttribute(“DataRate”, StringValue(“5Mbps”));

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

NetDeviceContainer devices;

devices = pointToPoint.Install(nodes);

// Install the Internet stack

InternetStackHelper stack;

stack.Install(nodes);

Ipv4AddressHelper address;

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

Ipv4InterfaceContainer interfaces = address.Assign(devices);

// Set up UDP server on Node 1

uint16_t port = 9;

UdpServerHelper server(port);

ApplicationContainer serverApp = server.Install(nodes.Get(1));

serverApp.Start(Seconds(1.0));

serverApp.Stop(Seconds(10.0));

// Set up UDP client on Node 0

UdpClientHelper client(interfaces.GetAddress(1), port);

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

client.SetAttribute(“Interval”, TimeValue(MilliSeconds(50)));

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

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

clientApp.Start(Seconds(2.0));

clientApp.Stop(Seconds(10.0));

// Connect packet sent and received callbacks

devices.Get(0)->TraceConnectWithoutContext(“PhyTxEnd”, MakeCallback(&PacketSentCallback));

devices.Get(1)->TraceConnectWithoutContext(“PhyRxEnd”, MakeCallback(&PacketReceivedCallback));

Simulator::Run();

Simulator::Destroy();

return 0;

}

Explanation:

Here, we had provided the detailed process of Maximum Deadline process in ns3

  1. TimeTag Class:
    • A custom Tag class TimeTag is defined to store the timestamp when the packet is sent.
    • This tag is serialized and deserialized with the packet.
  2. Simulation Setup:
    • Two nodes are created and connected using a point-to-point link.
    • The link is configured with a specific data rate and delay.
  3. Application Setup:
    • A UDP server is installed on the destination node (Node 1).
    • A UDP client is installed on the source node (Node 0) to send packets to the server.
  4. Packet Timestamps:
    • PacketSentCallback: Adds a TimeTag to the packet when it is sent, storing the current simulation time.
    • PacketReceivedCallback: Retrieves the TimeTag from the received packet and calculates the delay.
  5. Deadline Calculation:
    • A deadline of 100 milliseconds is used as an example.
    • The delay for each packet is compared to the deadline to determine if it meets the requirement.
  6. Running the Simulation:
    • The simulation runs for a specified period, during which packets are sent and received.
    • The delay for each packet is checked against the deadline, and the result is printed to the console.

In conclusion, we had learned how the Maximum Deadline validates the packets in the particular period of time by simulated through ns3. If you want to know further information about how the Maximum Deadline will performs in other alternative tools.