ns-3 Tutorial (Part IV) Wireless & Tracing System and Visualizing Results

(1)

JCSSE 2011's tutorials and workshops

Wednesday, 11 May 2011, 9:00 - 16:00

Intelligent Wireless Network Group

Department of Computer Engineering Faculty of Engineering, Kasetsart University http://iwing.cpe.ku.ac.th

ns-3 Tutorial (Part IV)

Wireless &

Tracing System and Visualizing Results

(2)

Time Table

 _{09:00 - 10:15 ns-3 Introduction & Installation}

 _{10:15 - 10.30 Break}

 _{10:30 - 12:00 Hands-On:}

Point-to-point and CSMA (Ethernet)

 _{12:00 - 13:00 Lunch}

 _{13:00 - 14:15 Hands-On:}

Wireless & Tracing System and Visualizing Results

 _{14:15 - 14:30 Break}

 _{14:30 - 15:30 Demonstation:}

ns-3 protocol stack modification

(3)

 _{Wireless modules overview}  _{Tracing with Trace Helpers}  _{Creating custom tracers}

 _{Visualizing and analyzing results}  _{Walk-through examples}

 _{Hands-on exercise}

(4)

 _{ns-3 provides a set of pre-conﬁgured trace sources}

 _{Users provide trace sinks and attach to the trace source}  _{Multiple trace sources can connect to a trace sink}

(5)

 _{Decouple trace sources from trace sinks:}

(6)

(7)

 _High-level

 _{Use a helper to hook a predefined trace source to an existing}

trace sink (e.g., ascii, pcap)

 _Mid-level

 _{Hook an existing trace source to a custom trace sink}

 _Low-level

 _{Add a new trace source and connect it to a special trace sink}

(8)

 _{Ascii Trace Helper}  _{Pcap Trace Helper}

(9)

Custom Trace Sink

void

DevTxTrace(

std::string context,

Ptr<const Packet> p, Mac48Address address) {

std::cout << " TX to=" << address << " p: " << *p << std::endl; }

:

Config::Connect(

"/NodeList/*/DeviceList/*/Mac/MacTx", MakeCallback(&DevTxTrace));

Name of trace sink function

(10)

 _{Task: model the network topology below in ns-3 and}

capture ECHO packets transmitted from N7 to N4

 _{We can start from tutorials/third.cc}

Walk-Through Example I (1)

N2 N3 N4 N0 N1 10.1.1.0/24 10.1.2.0/24 10.1.3.0/24 N5 N6 N7 ECHO

(11)

 _{CommandLine class allows processing of command-line}

arguments

 _{Supply default values of various attributes and variables}

Dissecting third.cc

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

bool verbose = true; uint32_t nCsma = 3; uint32_t nWifi = 3; CommandLine cmd;

cmd.AddValue ("nCsma", "Number of \"extra\" CSMA nodes/devices", nCsma); cmd.AddValue ("nWifi", "Number of wifi STA devices", nWifi);

cmd.AddValue ("verbose", "Tell echo applications to log if true", verbose); cmd.Parse (argc,argv);

(12)

 _{Various Helpers are available to help create wireless}

channel/physical/mac models

Dissecting third.cc

NodeContainer wifiStaNodes; wifiStaNodes.Create (nWifi);

NodeContainer wifiApNode = p2pNodes.Get (0);

YansWifiChannelHelper channel = YansWifiChannelHelper::Default ();

YansWifiPhyHelper phy = YansWifiPhyHelper::Default (); phy.SetChannel (channel.Create ());

WifiHelper wifi = WifiHelper::Default ();

(13)

 _{WiFi MAC layer}

Dissecting third.cc

NqosWifiMacHelper mac = NqosWifiMacHelper::Default (); Ssid ssid = Ssid ("ns-3-ssid");

mac.SetType ("ns3::StaWifiMac",

"Ssid", SsidValue (ssid),

"ActiveProbing", BooleanValue (false)); NetDeviceContainer staDevices;

staDevices = wifi.Install (phy, mac, wifiStaNodes); mac.SetType ("ns3::ApWifiMac",

"Ssid", SsidValue (ssid)); NetDeviceContainer apDevices;

Configure all nodes in wifiStaNodes container to be of

type “station”

Configure first node of point-to-point link

(14)

 _{All wireless nodes must be associated with mobility}  _{MobilityHelper provides a lot of help}

MobilityHelper mobility; mobility.SetPositionAllocator ("ns3::GridPositionAllocator", "MinX", DoubleValue (0.0), "MinY", DoubleValue (0.0), "DeltaX", DoubleValue (5.0), "DeltaY", DoubleValue (10.0), "GridWidth", UintegerValue (3),

"LayoutType", StringValue ("RowFirst"));

mobility.SetMobilityModel ("ns3::RandomWalk2dMobilityModel",

"Bounds", RectangleValue (Rectangle (-50, 50, -50, 50))); mobility.Install (wifiStaNodes); mobility.SetMobilityModel ("ns3::ConstantPositionMobilityModel"); mobility.Install (wifiApNode);

Dissecting third.cc

1 2 3 4

(MinX, MinY) DeltaX

(15)

 _{Create a copy of third.cc into the scratch dir and rename}

it to pm-ex1.cc

 _{Edit the source}

 _{Change port number from 9 to 7 (standard ECHO port)}

 _{Change PCAP file prefix to pm-ex1}

Walk-Through Example I (2)

$ cp examples/tutorials/third.cc scratch/pm-ex1.cc

UdpEchoServerHelper echoServer (7); :

UdpEchoClientHelper echoClient (csmaInterfaces.GetAddress (nCsma), 7);

pointToPoint.EnablePcapAll ("pm-ex1");

phy.EnablePcap ("pm-ex1", apDevices.Get (0));

(16)

 _{Run the script}

 _{Open the pcap files with WireShark}

Walk-Through Example I (3)

$ ls *.pcap

pm-ex1-0-0.pcap pm-ex1-0-1.pcap pm-ex1-1-0.pcap pm-ex1-1-1.pcap $ wireshark pm-ex1-0-0.pcap

(17)

 _{Visualize the simulation by adding option}

--visualize

 _{Press F3 to start the simulation}

Walk-Through Example I (4)

(18)

 _{Attributes can be configured and explored before the} simulation starts

Walk-Through Example I (5)

#include "ns3/gtk-config-store.h" GtkConfigStore config; config.ConfigureAttributes(); Simulator::Run ();

(19)

 _{GtkConfigStore can also be invoked in PyViz using Ipython}

shell

 _{Ipython must be installed}

(20)

 _{Task: Using the previous topology, replace ECHO traffic}

with CBR (Constant Bit Rate) traffic

Walk-Through Example II (1)

N2 N3 N4 N0 N1 10.1.1.0/24 10.1.2.0/24 10.1.3.0/24 N5 N6 N7 CBR (512 Kbps)

(21)

 _{Create pm-ex2.cc from pm-ex1.cc}

 _{Use OnOffHelper to generate CBR traffic from the client}

Walk-Through Example II (2)

$ cp scratch/pm-ex1.cc scratch/pm-ex2.cc uint16_t port = 9; OnOffHelper onoff( "ns3::UdpSocketFactory", InetSocketAddress("10.1.2.4", port)); onoff.SetAttribute("OnTime", StringValue("Constant:1")); onoff.SetAttribute("OffTime", StringValue("Constant:0")); onoff.SetAttribute("DataRate", StringValue("512Kbps")); onoff.SetAttribute("PacketSize", StringValue("512"));

ApplicationContainer apps = onoff.Install(wifiStaNodes.Get(nWifi-1)); apps.Start(Seconds(5.0));

Install app on node N7 only

(22)

 _{Create a packet sink on the server}

 _{Set simulation time to 30 seconds}

 _{Don't forget to change the PCAP trace prefix}

Walk-Through Example II (3)

PacketSinkHelper sink( "ns3::UdpSocketFactory", InetSocketAddress("10.1.2.4", port)); sink.Install(csmaNodes.Get(nCsma)); Simulator::Stop(Seconds(25.0)); Install PacketSink on node N4

(23)



_{Task: calculate average throughput from previous}

scenario



_Idea:

 _{Connect a custom trace sink to PacketSink's Rx trace source}  _{Compute average throughput from}

 _{first and last packets' timestamps}

 _{total bytes received}

(24)

 _{How to determine what trace source PacketSink}

provides?

 _{And how to get to it?}

 _{In ns-3 Doxygen, look for ns3::PacketSink (either via}

Class List or List of Trace Sources)

 _{Look at the documentation for GetTypeId}

(25)

 _{We now know that PacketSink object already comes with}

a trace source, called Rx

 _{We need to write a callback function to serve as a trace}

sink

Connecting Trace Source/Sink

PacketSink Object

(26)

 _{Quoted from ns-3 Tutorial:}

“…always try to copy someone else's working code…”

 _{Opening examples/csma/csma-ping.cc reveals}

 _{Then look at definition of SinkRx function:}

Callback Signature

$ find examples/ -name "*.cc" -exec grep -H PacketSink/Rx {} \;

examples/csma/csma-ping.cc: Config::ConnectWithoutContext ("/NodeList/3/ApplicationList/0/$ns3::PacketSink/Rx",

examples/csma/csma-packet-socket.cc: Config::Connect ("/NodeList/*/ApplicationList/*/$ns3::PacketSink/Rx",

examples/csma/csma-raw-ip-socket.cc: Config::ConnectWithoutContext ("/NodeList/3/ApplicationList/0/$ns3::PacketSink/Rx", :

:

Config::ConnectWithoutContext ("/NodeList/3/ApplicationList/0/$ns3::PacketSink/Rx", MakeCallback (&SinkRx));

(27)

 _{If no example can be found, look at ns-3 source code!}

 _{Either way, we now know that our callback's signature}

should be:

Callback Signature

$ find . -name "*.h" -exec grep -H TracedCallback {} \; :

./src/applications/udp-echo/udp-echo-client.h: TracedCallback<Ptr<const Packet> > m_txTrace; ./src/applications/v4ping/v4ping.h: TracedCallback<Time> m_traceRtt;

./src/applications/packet-sink/packet-sink.h: TracedCallback<Ptr<const Packet>, const Address &> m_rxTrace;

./src/mobility/mobility-model.h: TracedCallback<Ptr<const MobilityModel> > m_courseChangeTrace; ./src/routing/olsr/model/olsr-routing-protocol.h: TracedCallback <const PacketHeader &,

:

(28)

 _{Prepare trace sink callback and necessary statistical}

variables

Walk-Through Example III (2)

double firstRxTime = -1.0, lastRxTime; uint32_t bytesTotal = 0;

void SinkRxTrace(Ptr<const Packet> pkt, const Address &addr) { if (firstRxTime < 0) firstRxTime = Simulator::Now().GetSeconds(); lastRxTime = Simulator::Now().GetSeconds(); bytesTotal += pkt->GetSize(); } $ cp scratch/pm-ex2.cc scratch/pm-ex3.cc

(29)

 _{Connect trace source with trace sink}

 _{Produce statistical report at the end of the script}

 _{Run the simulation script}

Walk-Through Example III (3)

Config::ConnectWithoutContext(

"/NodeList/*/ApplicationList/*/$ns3::PacketSink/Rx", MakeCallback(&SinkRxTrace));

cout << "Avg throughput = "

<< bytesTotal*8/(lastRxTime-firstRxTime)/1024 << " kbits/sec" << endl;

(30)

 _{Task: study impact of number of clients on average} throughput  _{Experiment setup}  _{2-14 mobile clients}  _{UDP CBR stream}  _{512 Kbps per client}

 Packet size: 512 bytes

(31)

 _{Modify the source so that OnOff application is installed}

on all WiFi stations

 _{Change the line:}

to

Walk-Through Example IV (2)

$ cp scratch/pm-ex3.cc scratch/pm-ex4.cc

ApplicationContainer apps = onoff.Install(wifiStaNodes);

(32)

 _{Report the number of WiFi stations in addition to the}

average throughput

 _{Try running the script with various values specified for} nWifi argument

Walk-Through Example IV (3)

cout << "Num clients = " << nWifi << " " << "Avg throughput = "

<< bytesTotal*8/(lastRxTime-firstRxTime)/1024 << " kbits/sec" << endl;

$ waf --run "pm-ex4 --nWifi=1" 2> /dev/null

Num clients = 1 Avg throughput = 512.96 kbits/sec $ waf --run "pm-ex4 --nWifi=2" 2> /dev/null

Num clients = 2 Avg throughput = 1025.54 kbits/sec

suppress stderr messages

(33)

 _{Create a shell-script, named run-all.sh, that runs the}

simulation with different values for nWifi

 _{Run the shell-script and redirect all stdout messages to a}

file

Walk-Through Example IV (4)

#!/bin/bash

for ((i=2; i<=14; i += 2)); do waf --run "pm-ex4 --nWifi=$i" done

(34)

 _{Visualize results with gnuplot}

Walk-Through Example IV (5)

$ gnuplot

(35)

 _{Create a script, genplot.gnuplot, for generating a}

plot as a PNG file

 _Also

 _{Change x-axis to load,}

 _{Polish the plot: turn on grid, turn off legend}

Walk-Through Example IV (6)

#!/usr/bin/gnuplot set terminal png

set output 'graph.png' set xrange [0:]

set yrange [0:]

set xlabel 'Load (kb/s)'

set ylabel 'Average Throughput (kb/s)' set grid

(36)

 _{Run the plotting script}

Walk-Through Example IV (7)

(37)

 _{Publication-quality results should be obtained from many}

replications in each scenario

 _{Use --RngRun=<run-number> to change random}

sequence

Running Multiple Replications

(38)

 _{Study impact of number of mobile stations to packet}

delivery ratio