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NS-3 Tutorial

NS-3 Tutorial. 2013.05.16 Hojin Lee. 내 용. NS-3 현황 / 설치 핵심 클래스 보조 클래스 간단 예제 로그 트레이스 그 외 . 시작하기 전에 …. 이 슬라이드는 제가 만든 부분도 있지만 , 인터넷에서 검색되는 다른 분이 만든 슬라이드도 많이 이용했습니다 . 그 분들께 심심한 감사를 …. NS-3. Ns-3 is targeted at networking research. NS-3 status. Periodic update

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NS-3 Tutorial

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  1. NS-3 Tutorial 2013.05.16 Hojin Lee

  2. 내용 • NS-3 현황 / 설치 • 핵심 클래스 • 보조 클래스 • 간단 예제 • 로그 • 트레이스 • 그 외..

  3. 시작하기 전에… • 이 슬라이드는 제가 만든 부분도 있지만, 인터넷에서 검색되는 다른 분이 만든 슬라이드도 많이 이용했습니다. • 그 분들께 심심한 감사를…

  4. NS-3 • Ns-3 is targeted at networking research.

  5. NS-3 status • Periodic update • Latest version is ns-3.17 (May 2013) • Supporting platform • FreeBSD, Linux, SunOS, Solaris, Windows (cygwin), OS X • Free, open source software project • Website • http://www.nsnam.org/ • Can find the doxygen, reference manual, and tutorial

  6. NS-3 components • Ns-3 simulator • Pre-processing • Traffic / topology generation • Alignment with real systems (sockets, device driver interfaces) • Post-processing • Ns-3 output file (trace file) analysis • Throughput, delay, jitter, drop • Various tracing system • Graph • xgraph, gnuplot

  7. NS-3 all-in-one package Directory Structure Example simulation scripts

  8. How to Install NS-3 • Ns-3 download: http://www.nsnam.org/download.html • ns-allinone-3.12.1.tar.bz2 • [root@mwnl ~]# tar xvf ns-allinone-3.12.1.tar.bz2 • [root@mwnl ~]# cd ns-allinone-3.12.1 • Building • [root@mwnl ~/ns-allinone-3.12.1]# ./build.py • Setting environment • [root@mwnl ~/ns-allinone-3.12.1/ns-3.12.1]# ./waf –d optimized configure • [root@mwnl ~/ns-allinone-3.12.1/ns-3.12.1]# ./waf –d debug configure • [root@mwnl ~/ns-allinone-3.12.1/ns-3.12.1]# ./waf • [root@mwnl ~/ns-allinone-3.12.1/ns-3.12.1]# ./test.py –c core

  9. Simple Example • cd ns-allinone-3.12.1/ns-3.12.1 • /ns-3.12.1$ ./waf --run scratch/scratch-simulator • Output

  10. Workspace • /ns-allinone-3.12.1/ns-3.12.1/scratch • Run program only in the scratch folder • Run program by the commands below • ./waf --run scratch/example • (or) ./waf --run example

  11. 핵심 클래스 • Node • 패킷을 주고 받는 노드 • 이 자체는 특별한 기능이 없음 • 여기에 네트워크 장치, 네트워크 프로토콜 스택등을 설치해야 함 • NetDevice • 네트워크 장치 • PointToPointNetDevice, CsmaNetDevice, WifiNetDevice, … • Channel • 네트워크 채널: 정보가 흘러가는 논리적 경로 • 일반적으로 NetDevice와 1:1 대응 • PointToPointChannel, CsmaChannel, WifiChannel, … • Application • 응용 • UdpEchoSever, UdpEchoClient, OnOffApplication, BulkSendApplication, …

  12. NS-3 기본 모델 Application Application Application Application Sockets-like API Protocol stack Protocol stack Packet(s)‏ Node Node NetDevice NetDevice NetDevice Channel NetDevice Channel

  13. 보조 클래스 • 핵심클래스 + @로부터 시뮬레이션 시나리오 작성을 도와주는 클래스 • XXXContainer • 그릇: 벡터를 품고 있음 일괄작업 용이 • std::vector<Ptr<XXX> > • 주요 멤버함수 • Ptr<XXX> Get (uint32_t) • uint32_t GetN () • NodeContainer, NetDeviceContainer, Ipv4InterfaceContainer, ApplicationContainer • XXXHelper • 생성 및 설치를 도움 • 생성: 공장(ObjectFactory)을 품고 있음 • 주요 멤버함수 • SetYYY (…): 찍어낼 객체의 속성을 정함 • Install (…): 객체를 생성해서 설치 (생성된 객체를 담아서 XXXContainer로 리턴)

  14. 간단 예제 (1/3) • 노드2개 사이에 point-to-point 링크, 패킷 한 개 echo #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" using namespace ns3; NS_LOG_COMPONENT_DEFINE ("FirstScriptExample"); int main (intargc, char *argv[]) { LogComponentEnable("UdpEchoClientApplication", LOG_LEVEL_INFO); LogComponentEnable("UdpEchoServerApplication", LOG_LEVEL_INFO); NodeContainer nodes; nodes.Create (2); PointToPointHelperpointToPoint; pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps")); pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms")); NetDeviceContainer devices; devices = pointToPoint.Install (nodes);

  15. 간단 예제(2/3) InternetStackHelper stack; stack.Install (nodes); Ipv4AddressHelper address; address.SetBase ("10.1.1.0", "255.255.255.0"); Ipv4InterfaceContainer interfaces = address.Assign (devices); UdpEchoServerHelper echoServer (9); ApplicationContainer serverApps = echoServer.Install (nodes.Get (1)); serverApps.Start (Seconds (1.0)); serverApps.Stop (Seconds (10.0)); UdpEchoClientHelper echoClient (interfaces.GetAddress (1), 9); echoClient.SetAttribute ("MaxPackets", UintegerValue (1)); echoClient.SetAttribute ("Interval", TimeValue (Seconds (1.))); echoClient.SetAttribute ("PacketSize", UintegerValue (1024)); ApplicationContainer clientApps = echoClient.Install (nodes.Get (0)); clientApps.Start (Seconds (2.0)); clientApps.Stop (Seconds (10.0)); Simulator::Run (); Simulator::Destroy (); return 0; }

  16. 간단 예제(2/3) • ../ns-3.12.1] ./waf –-run scratch/example1 • Output Sent 1024 bytes to 10.1.1.2 Received 1024 bytes from 10.1.1.1 Received 1024 bytes from 10.1.1.2

  17. 로그 (1/2) • 맞게 잘 짰나? • 어, 왜 안되지……? • gdb • printf • 컴포넌트별로, 수준별로 로그를 on/off • src/applications/model/udp-echo-client.cc NS_LOG_COMPONENT_DEFINE ("UdpEchoClientApplication"); … void UdpEchoClient::Send (void) { NS_LOG_FUNCTION (this); … if (Ipv4Address::IsMatchingType (m_peerAddress)) { NS_LOG_INFO ("At time " << Simulator::Now ().GetSeconds () << "s client sent " << m_size << " bytes to " << Ipv4Address::ConvertFrom (m_peerAddress) << " port " << m_peerPort); } … }

  18. 로그 (2/2) • 로그 매크로 • NS_LOG_ERROR • NS_LOG_WARN • NS_LOG_DEBUG • NS_LOG_INFO • NS_LOG_FUNCTION • NS_LOG_LOGIC • NS_LOG_ALL • NS_LOG_UNCOND • 로그 켜기 • 시나리오 스크립트 수정: LogComponent (“컴포넌트명”, 로그수준) • 로그 수준: NS_ 제외, LOG_LEVEL_XXX로 하면 누적 • 환경변수: export 컴포넌트명=로그수준 • 로그수준: 소문자, NS_LOG_ 제외, level_xxx로 하면 누적

  19. 트레이스 • 시뮬레이션의 목적 – 성능 평가 • 트레이스로부터… • High level • 시뮬레이터에서 제공하는 종합적인 트레이스 이용 • 트레이스 파일을 나의 목적에 맞게 parsing해야 함 • Low level • 내가 원하는 자료만 출력이 되도록 매번 직접 소스 코드를 수정 • Mid level • ???

  20. High Level (1/3) • IP 이상 계층 • void InternetStackHelper::EnableAsciiIpv4All (std::string prefix) • void InternetStackHelper::EnablePcapIpv4All (std::string prefix) • Mac 이상 계층 • void AsciiTraceHelperForDevice::EnableAscii (std::string prefix) • void PcapHelperForDevice::EnableAscii (std::string prefix) + 2 /NodeList/0/DeviceList/0/$ns3::PointToPointNetDevice/TxQueue/Enqueue ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 ttl 64 id 0 protocol 17 offset 0 flags [none] length: 1052 10.1.1.1 > 10.1.1.2) ns3::UdpHeader (length: 1032 49153 > 9) Payload (size=1024) - 2 /NodeList/0/DeviceList/0/$ns3::PointToPointNetDevice/TxQueue/Dequeue ns3::PppHeader (Point-to-Point Protocol: IP (0x0021)) ns3::Ipv4Header (tos 0x0 ttl 64 id 0 protocol 17 offset 0 flags [none] length: 1052 10.1.1.1 > 10.1.1.2) ns3::UdpHeader (length: 1032 49153 > 9) Payload (size=1024)

  21. High Level (2/3) • PCAP Tracing • .pcap file format • Traffic trace analyze • pointToPoint.EnablePcapAll (“myfirst”); • Reading output with tcpdump $ tcpdump -nn -tt -r myfirst-0-0.pcap reading from file myfirst-0-0.pcap, link-type PPP (PPP) 2.000000 IP 10.1.1.1.49153 > 10.1.1.2.9: UDP, length 1024 2.514648 IP 10.1.1.2.9 > 10.1.1.1.49153: UDP, length 1024 $ tcpdump -nn -tt -r myfirst-1-0.pcap reading from file myfirst-1-0.pcap, link-type PPP (PPP) 2.257324 IP 10.1.1.1.49153 > 10.1.1.2.9: UDP, length 1024 2.257324 IP 10.1.1.2.9 > 10.1.1.1.49153: UDP, length 1024

  22. High Level (3/3) • Reading output with Wireshark • http://www.wireshark.org/download.html

  23. Mid Level • Trace source와 trace sink의 분리 • Trace source • 원천, • 관심이 있는 상태의 변화가 발생하거나, 관심 있는 데이터 변경 시 그 이벤트를 생성 • 평소에는 비활성화, trace sink와 연결(connect)해야 활성화 됨 • 미리 프로그램되어 있음 • Trace sink • 이벤트 및 관련 정보를 소비 • 사용자가 추가

  24. Mid Level • Callback • The object is to allow a piece of code to call a function without any specific inter-module dependency • Treat the address of the called function as a variable, i.e. a pointer-to-function variable • Decouple the calling function from the called class completely • Relation between tracing system and callback • A trace source is a callback • When a trace sink wants to know information given by a trace source, it add its own function to the callback list. • It is good for students who want to know callbacks further to refer callback part in ns-3 manual pp.12-14.

  25. 간단 예제(1/2) #include "ns3/object.h" #include "ns3/uinteger.h" #include "ns3/traced-value.h" #include "ns3/trace-source-accessor.h" #include <iostream> using namespace ns3; class MyObject : public Object { public: static TypeIdGetTypeId (void) { static TypeIdtid = TypeId ("MyObject") .SetParent (Object::GetTypeId ()) .AddConstructor<MyObject> () .AddTraceSource ("MyInteger", "An integer value to trace.", MakeTraceSourceAccessor (&MyObject::m_myInt)) ; return tid; } MyObject () {} TracedValue<int32_t> m_myInt; }; Provides the “hooks” used for connecting the trace source to the outside the config system Provides the infrastructure that overloads the operators and drives callback process

  26. 간단 예제(2/2) void IntTrace (int32_t oldValue, int32_t newValue) { std::cout << "Traced " << oldValue << " to " << newValue << std::endl; } int main (intargc, char *argv[]) { Ptr<MyObject> myObject = CreateObject<MyObject> (); myObject->TraceConnectWithoutContext ("MyInteger", MakeCallback(&IntTrace)); myObject->m_myInt = 1234; } Trace sink; callback function: this function will be called whenever the overloaded operators of the TracedValue is excuted Connect between trace source and trace sink Operator”=” invoke the Callback

  27. Mid Level • TracedValue <xxx> • 연산자 overloading • Callback 함수의 인자가 고정 • TracedCallback <…> • TracedValue보다 flexible

  28. TracedCallback간단 예제 void CourseChange (std::string context, Ptr<constMobilityModel> model) { Vector position = model->GetPosition (); NS_LOG_UNCOND (context << " x = " << position.x << ", y = " << position.y); } //Trace Sink std::ostringstreamoss; oss << "/NodeList/" << wifiStaNodes.Get (nWifi - 1)->GetId () << "/$ns3::MobilityModel/CourseChange"; //Config Path Config::Connect (oss.str (), MakeCallback (&CourseChange)); //Connection between Trace Source and Sink Output Result:/NodeList/7/$ns3::MobilityModel/CourseChange x = 7.27897, y = 2.22677 …

  29. Mid Level • boolObjectBase::TraceConnectWithoutContext (std::string name, constCallbackBase& cb) • void Config::ConnectWithoutContext (std::string path, const Callback& cb) • 멤버 함수 아님 (Config– namespace) • path • Trace sources • http://www.nsnam.org/docs/release/3.16/doxygen/group___trace_source_list.html

  30. Config • name, full name  attribute system • void Config::SetDefault (std::string name, constAttributeValue& value) • void Config::Set (std::string path, constAttributeValue& value) • AttributeValue • IntegerValue, UintegerValue, DoubleValue, StringValue, …

  31. NS-3 Type System • The aggregation mechanism needs information about the type of objects at runtime • The attribute mechanism needs information about the attributes supported by a specific object • The tracing mechanism needs information about the trace sources supported by a specific object • All this information is stored in NS-3::TypeId; • The parent type • The name of the type • The list of attributes (their name, their type, etc.) • The list of trace sources (their name, their type, etc.) NS-3

  32. 시뮬레이션 파라미터설정 (1/2) • 명령행 인자로 시뮬레이션 파라미터를 바꿀 수 있음 • main 함수 내에 아래 두 줄 추가 CommandLinecmd; cmd.Parse (argc, argv); • 예제 • ./waf --run "scratch/example1 --PrintHelp” • ./waf –-run “scratch/example1 --PrintAttributes=ns3::PointToPointNetDevice” • ./waf --run “scratch/example1 --ns3::PointToPointNetDevice::DataRate=5Mbps –ns3::PointToPointChannel::Delay=2ms”

  33. 시뮬레이션 파라미터설정 (2/2) • 명령행 인자 변수를 추가할 수 있음 • cmd.AddValue(…) 이용 • 예제 int main (intargc, char *argv[]) { uint32_t nPackets =1; CommandLinecmd; cmd.AddValue("nPackets", "Number of packets to echo", nPackets); Cmd.Parse (argc, argv); … echoClient.SetAttribute (“MaxPackets”, UintegerValue (nPackets)); • ./waf --run “scratch/example1 --nPackets=2”

  34. TIPs • 작은 걸음 • Refactoring • 중복제거, 가독성 • 부채 • 사람의 실수가 개입할 여지가 없게 • 구체화와 추상화

  35. 추천 도서 • 실용주의 프로그래머 • 리팩터링: 코드 품질을 개선하는 객체지향 사고법 • 임베디드C를 위한 TDD • 테스트 주도 개발 • 익스트림 프로그래밍

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