Transcript Differentiated Service over Content-Centric Networking

Introduction to NS3
2014.9.23
Dohyung Kim
Computer network lab, [email protected]
Computer Network Laboratory
Why simulate?
 Field tests are expensive
 Experiments can be hard to reproduce
 Collaboration is not easy
Computer Network Laboratory
What is NS?
 NS is a discrete-event network simulator for internet
system
- Protocol design, prototyping, multiple level of abstraction
 NS has a companion network animator called nam
Has been called the nsnam
project
Computer Network Laboratory
NS history (~ns-2)
1995
1997
• Ns-1 (LBNL)
- C++, Tcl
- Event driven
2000
• Core Ns-2 development
- split object architecture
- detailed TCP models
- scheduler, queuing, links
- routing, wireless, satellite
- nam, topology generator
Computer Network Laboratory
• Mainly integration of
contributed code
- Sensor network MAC and
routing
- SCTP and XCP
- Wireless enhancement
Ns-2 impact
 Over 50% of ACM and IEEE network simulation papers
from 200s0-2004 cite the use of ns-2
* Source: ACM Digital Library and IEEExplore searches
Computer Network Laboratory
Skepticism abounds
“For years, the community had to rely on simulators, which now seem a
little dated, and it’s not clear who was convinced to adopt anything new
based on ns2 simulations;”
* Nick McKeown, VINI public review, ACM Sigcomm 2006
“...Tragedy of the Commons...”
“...around 50% of the papers appeared to be... bogus...”
“Who has ever validated NS2 code?”
“To be honest, I'm still not sure whether I will use a simulation in a
paper.”
“...I will have a hard time accepting or advocating the use of NS-2
or any other simulation tool”
* September 2005 archives of the e2e-interest mailing list
Computer Network Laboratory
Trends
Many researcher move away from simulation
 Experiments and testbed start to be preferred in major
conference papers
- PlanetLab, OneLab, VINI, Emulab, ORBIT, WhyNet,..
Yet simulation tools proliferate
 Ns-2, OMNET++, NetSim, NCTUns, QualNet, OPNET,
P2PSim, ONE, …
Computer Network Laboratory
NS-3








A discrete event simulator
Modular design / Open source
Actively developed (contrast to NS-2)
Developed in C++ / Python biding available
Live visualizer
Logging facility for debugging
Tracing facility of getting output
Direct Code Execution (DCE)
- Can be connected to a real network
Computer Network Laboratory
Discrete Event Simulator





Simulation time moves directly from event to event
Schedule events to occur at specific simulation times
A simulation scheduler orders the event execution
Simulator execute events one by one
Simulation stops at specific time or when events end
Computer Network Laboratory
NS-3 Component
 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
Computer Network Laboratory
Installation
 www.nsnam.org
 Latest release ns-3.21
- Source download link
 https://www.nsnam.org/release/ns-allinone3.21.tar.bz2
- Documentation download link
 http://www.nsnam.org/ns-3-21/documentation
 Installation manual
- http://www.nsnam.org/wiki/Installation
Computer Network Laboratory
How to Install
 Building
- [user@eins ~/ns-allinone-3.21]# ./build.py
 Setting environment
- [user@eins~/ns-allinone-3.21/ns-3.21]# ./waf –d optimized
configure
- [user@com ~/ns-allinone-3.21/ns-3.21]# ./waf -d
debug --enable-examples --enable-tests configure
- [user@com ~/ns-allinone-3.21/ns-3.21]# ./waf
- [user@com ~/ns-allinone-3.15/ns-3.15]# ./test.py –c core
Computer Network Laboratory
Workspace
 /ns-allinone-3.21/ns-3.21/scratch
 Run program only in the scratch folder
 Run program by the commands below
- ./waf --run scratch/example
- (or) ./waf --run example
Computer Network Laboratory
NS-3 Basic Model
Application
Application
Application
Application
Sockets-like
API
Protocol
stack
Packet(s)
Protocol
stack
Node
NetDevice
NetDevice
Node
Channel
Channel
Computer Network Laboratory
NetDevice
NetDevice
Core Classes
 Node
- No specific functionality
- Host(end system) in the Internet
- Install a net device and a network protocol
 Application
- A user program that generates some activity to be simulated
- UdpEchoServer, UdpEchoClient, OnOffApplication,
BulkSendApplication, …
Computer Network Laboratory
Core Classes
 Channel
- Medium connected by nodes over which data flows
- Generally one-to-one mapped with NetDevice
- PointToPointchannel, CsmaChannel, WifiChannel, …
 NetDevice
- Like a specific kind of network cable and a hardware device
- Provides methods for managing connection to Node and channel
- PointToPointNetDevice, CsmaNetDevice, WifiNetDevice, …
Computer Network Laboratory
Helper API
 A set of classes and methods that make common
operation easier than using low level APIs
 Consists of
- Container objects
- Helper classes
Computer Network Laboratory
Container
 A part of the ns-3 “helper API”
 Often simulation will need to do a number of identical
actions to group of objects
 The helper API makes heavy use of containers of similar
objects to which similar to identical operation can be
performed
Computer Network Laboratory
Helper classes
 Each function does a single operation on a “set of same
objects”
 Provides simple ‘syntactical sugar’ to make simulation
scripts look nicer and easier to read for network
researchers
Computer Network Laboratory
Container and Helper
Computer Network Laboratory
Container and Helper example
Computer Network Laboratory
Attribute
 Attributes are exported into a string-based namespace,
with filesystem-like paths
- namespace supports regular expressions
- Nodes with NodeIds 1, 3, 4, 5, 8, 9, 10, 11:
 “/NodeList/[3-5]|[8-11]|1”
 Attributes also can be used without the paths
- e.g. “ns3::WifiPhy::TxGain”
Computer Network Laboratory
Attribute
 A Config class allows users to manipulate the attributes
- e.g.: Set a default initial value for a variable
 Config::Set (“ns3::WifiPhy::TxGain”, DoubleValue (1.0));
- Syntax also supports string values:
 Config::Set (“WifiPhy::TxGain”, StringValue (“1.0”));
- AttributeValue
 IntegerValue, UintegerValue, DoubleValue, StringValue, …
Computer Network Laboratory
Attribute
 Attribute namespace
- strings are used to describe
paths through the namespace
 Refer to doxygen documents
Computer Network Laboratory
NS-3 program structure
Computer Network Laboratory
Simulation procedure
1. Turning on logging
2. Creating network topology
3. Creating application
4. Running simulator
Computer Network Laboratory
Simulation procedure
 Turning on logging
- Define log component
 NS_LOG_COMPONENT_DEFINE ( name )
- Enable log component
 LogComponentEnable ( name, level )
Computer Network Laboratory
Logging Module





Output messages from modules
Useful when debugging
NS_LOG environment variable
NS_LOG_FUNCTION level information
Verbosity level
-
NS_LOG_ERROR — Log error messages;
NS_LOG_WARN — Log warning messages;
NS_LOG _EBUG — Log relatively rare debugging messages;
NS_LOG_INFO — Log informational messages about program progress;
NS_LOG_FUNCTION — Log a message describing each function called;
NS_LOG_LOGIC – Log messages describing logical flow within a function;
NS_LOG_ALL — Log everything.
NS_LOG_UNCOND – Log the associated message unconditionally.
Computer Network Laboratory
Command Line Arguments
 Change the simulation parameters using command line arguments
 First declare the command line parser in main function
CommandLine cmd;
cmd.Parse (argc, argv);
 Example
-
./waf --run "scratch/example1 –PrintHelp”
./waf –-run “scratch/example1 –PrintAttributes=ns3::PointToPointNetDevice”
./waf --run “scratch/example1 -ns3::PointToPointNetDevice::DataRate=5Mbps –
ns3::PointToPointChannel::Delay=2ms”
Computer Network Laboratory
Command Line Arguments
 When add your own hooks.
- cmd.AddValue in main function
 Example
int
main (int argc, char *argv[])
{
uint32_t nPackets =1;
CommandLine cmd;
cmd.AddValue("nPackets", "Number of packets to echo", nPackets);
Cmd.Parse (argc, argv);
…
echoClient.SetAttribute (“MaxPackets”, UintegerValue (nPackets));
 ./waf --run “scratch/example1 –nPackets=2”
Computer Network Laboratory
Simulation procedure
 Creating Network Topology
- Use Topology Helpers
- NodeContainer
 NodeContainer Ptr<Node>
 NodeContainer::Create (n)
e.g.) NodeContainer nodes;
nodes.Create (2);
Computer Network Laboratory
n: # of Nodes
CreateObject<> ();
 CreateObject<> is a wrapper for operator new.
 ns3::Object objects must be created on the heap using
CreateObject<> (), which returns a smart pointer; e.g.
Ptr<Node> rxNode = CreateObject<Node> ();
Computer Network Laboratory
Create<> ();
 Create<> is simply a wrapper around operator new that
correctly handles the reference counting system
 For objects deriving from class SimpleRefCount
Ptr<Packet> p = Create<Packet> (data,size);
Computer Network Laboratory
Simulation Procedure
PointToPointHelper
void PointToPointHelper::SetDeviceAttribute (name, value)
void PointToPointHelper::SetChannelAttribute (name, value)
NetDeviceContainer PointToPointHelper::Install
(NodeContainer c)
NetDeviceContainer
NetDeviceContainer Ptr<NetDevice>
PointToPointHelper pointToPoint;
pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));
pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms"));
NetDeviceContainer devices;
devices = pointToPoint.Install (nodes);
Computer Network Laboratory
Simulation Procedure
UdpEchoServerHelper
UdpEchoServerHelper::UdpEchoServerHelper ( port )
ApplicationContainer UdpEchoServerHelper::Install (NodeContainer c )
UdpEchoClientHelper
UdpEchoClientHelper::UdpEchoClientHelper ( ip, port )
void UdpEchoClientHelper::Setattribute ( name, value )
ApplicationContainer UdpEchoClientHelper::Install (NodeContainer c )
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 (1.0)));
echoClient.SetAttribute ("PacketSize", UintegerValue (1024));
ApplicationContainer clientApps = echoClient.Install (nodes.Get (0));
clientApps.Start (Seconds (2.0)); clientApps.Stop (Seconds (10.0));
Computer Network Laboratory
 Start Simulator
- Simulator::Run ();
 Destroy Simulator
- Simulator::Destroy ();
Computer Network Laboratory
Simulation Example
UDP
EchoClient
10.1.1.1
P2P interface
UDP
EchoServer
10.1.1.2
P2P interface
Data rate: 5Mbps, Delay: 2ms
Transmit a packet at 1s
Upon receiving the packet, echo it
Computer Network Laboratory
• Simple point-to-point link between two nodes and echo a single packet
#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 (int argc, char *argv[])
{
LogComponentEnable("UdpEchoClientApplication", LOG_LEVEL_INFO);
LogComponentEnable("UdpEchoServerApplication", LOG_LEVEL_INFO);
NodeContainer nodes;
nodes.Create (2);
PointToPointHelper pointToPoint;
pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));
pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms"));
NetDeviceContainer devices;
devices = pointToPoint.Install (nodes);
Computer Network Laboratory
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 (1.0)));
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;
Computer Network Laboratory
Simulation Example
 ../ns-3.20] ./waf --run scratch/example1
 Output
At
At
At
At
time
time
time
time
2s client sent 1024 bytes to 10.1.1.2 port 9
2.00369s server received 1024 bytes from 10.1.1.1 port 49153
2.00369s server sent 1024 bytes to 10.1.1.1 port 49153
2.00737s client received 1024 bytes from 10.1.1.2 port 9
Computer Network Laboratory
Tracing System
 Tracing is a structured form of simulation output
Computer Network Laboratory
ASCII Tracing
AsciiTraceHelper ascii;
pointToPoint.EnableAsciiAll (ascii.CreateFileStream(“myfirst.tr”));
Simulator::Run ();
Simulator::Destroy ();
return 0;
 Output (myfirst.tr)
+ 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)
Computer Network Laboratory
ASCII Tracing
00 +
<operation – enqueue operation>
01 2
<simulation time>
02
/NodeList/0/DeviceList/0/$ns3::PointToPointNetDevice/TxQueue/Enq
ueue <trace source>
03 ns3::PppHeader (
04 Point-to-Point Protocol: IP (0x0021)) <Link-layer header info>
05 ns3::Ipv4Header (
06 tos 0x0 ttl 64 id 0 protocol 17 offset 0 flags [none]
07 length: 1052 10.1.1.1 > 10.1.1.2)
<IP-header header info>
08 ns3::UdpHeader (
09 length: 1032 49153 > 9)
<TCP-header info>
10 Payload (size=1024)
<payload info>
Computer Network Laboratory
PCAP Tracing
 Generating packet trace file in .pcap format
 Can read the .pcap file with Wireshark or tcpdump
 http://www.wireshark.org/download.html
 Example
pointToPoint.EnablePcapAll (“myfirst”); //Right before the call to Simulator::Run()
Computer Network Laboratory
44
Tracing

src/internet/model/tcp-tahoe.cc
src/internet/model/tcp-tahoe.h
Computer Network Laboratory
Tracing
Callback Function
Static void
CwndChange (uint32_t oldCwnd, uint32_t newCwnd)
{
NS_LOG_UNCOND (Simulator::Now ().GetSeconds () << “\t” << newCwnd);
}
Static void
RxDrop (Ptr<const Packet> p)
{
NS_LOG_UNCON (“RxDrop at” << Simulator::Now ().GetSeconds ();
}
Connect a trace source and trace sink
ns3TcpSocket->TraceConnectWithoutContext (“CongestionWindow”, MakeCallback
(&CwndChange));
devices.Get(1)->TraceConnectWithoutContext (“PhyRxDrop”, MakeCallback (&RxDrop));
Computer Network Laboratory
Tracing Example
#include
#include
#include
#include
#include
#include
<fstream>
"ns3/core-module.h“
"ns3/network-module.h“
"ns3/internet-module.h“
"ns3/point-to-point-module.h“
"ns3/applications-module.h“
MyApp::MyApp ()
: m_socket (0),
m_peer (),
m_packetSize (0),
m_nPackets (0),
m_dataRate (0),
m_sendEvent (),
m_running (false),
m_packetsSent (0)
{
}
using namespace ns3;
NS_LOG_COMPONENT_DEFINE ("FifthScriptExample");
class MyApp : public Application
{
public:
Create a simple application
MyApp ();
virtual ~MyApp();
void Setup (Ptr<Socket> socket, Address address,
uint32_t packetSize, uint32_t nPackets, DataRate
dataRate);
private:
virtual void StartApplication (void);
virtual void StopApplication (void);
void ScheduleTx (void);
void SendPacket (void);
Ptr<Socket>
Address
uint32_t
uint32_t
DataRate
EventId
bool
uint32_t
m_socket;
m_peer;
m_packetSize;
m_nPackets;
m_dataRate;
m_sendEvent;
m_running;
m_packetsSent;};
MyApp::~MyApp()
{
m_socket = 0;
}
void
MyApp::Setup (Ptr<Socket> socket, Address address,
uint32_t packetSize, uint32_t nPackets, DataRate
dataRate){
m_socket = socket;
m_peer = address;
m_packetSize = packetSize;
m_nPackets = nPackets;
m_dataRate = dataRate;
}
void
MyApp::StartApplication (void)
{
m_running = true;
m_packetsSent = 0;
m_socket->Bind ();
m_socket->Connect (m_peer);
SendPacket ();
}
Computer Network Laboratory
Tracing Example
void
MyApp::StopApplication (void)
{
m_running = false;
Trace sink
static void
CwndChange (uint32_t oldCwnd, uint32_t newCwnd)
{
NS_LOG_UNCOND (Simulator::Now ().GetSeconds () << "\t" << newCwnd);
}
if (m_sendEvent.IsRunning ())
{
Simulator::Cancel (m_sendEvent);
}
static void
RxDrop (Ptr<const Packet> p)
{
NS_LOG_UNCOND ("RxDrop at " << Simulator::Now ().GetSeconds ());
}
if (m_socket)
{
m_socket->Close ();
}
}
void
MyApp::SendPacket (void)
{
Ptr<Packet> packet = Create<Packet> (m_packetSize);
m_socket->Send (packet);
if (++m_packetsSent < m_nPackets)
{
ScheduleTx ();
}
int
main (int argc, char *argv[])
{
NodeContainer nodes;
nodes.Create (2);
PointToPointHelper pointToPoint;
pointToPoint.SetDeviceAttribute ("DataRate", StringValue ("5Mbps"));
pointToPoint.SetChannelAttribute ("Delay", StringValue ("2ms"));
NetDeviceContainer devices;
devices = pointToPoint.Install (nodes);
}
void
MyApp::ScheduleTx (void)
{
if (m_running)
{
Time tNext (Seconds (m_packetSize * 8 /
static_cast<double> (m_dataRate.GetBitRate ())));
m_sendEvent = Simulator::Schedule (tNext,
&MyApp::SendPacket, this);
}
}
Ptr<RateErrorModel> em = CreateObjectWithAttributes<RateErrorModel> (
"RanVar", RandomVariableValue (UniformVariable (0., 1.)),
"ErrorRate", DoubleValue (0.00001));
devices.Get (1)->SetAttribute ("ReceiveErrorModel", PointerValue
(em));
InternetStackHelper stack;
stack.Install (nodes);
Ipv4AddressHelper address;
address.SetBase ("10.1.1.0", "255.255.255.252");
Ipv4InterfaceContainer interfaces = address.Assign (devices);
Computer Network Laboratory
Tracing Example
uint16_t sinkPort = 8080;
Address sinkAddress
(InetSocketAddress(interfaces.GetAddress (1),
sinkPort));
PacketSinkHelper packetSinkHelper
("ns3::TcpSocketFactory", InetSocketAddress
(Ipv4Address::GetAny (), sinkPort));
ApplicationContainer sinkApps =
packetSinkHelper.Install (nodes.Get (1));
sinkApps.Start (Seconds (0.));
sinkApps.Stop (Seconds (20.));
TCP sink application
Ptr<Socket> ns3TcpSocket =
Socket::CreateSocket (nodes.Get (0),
TcpSocketFactory::GetTypeId ());
ns3TcpSocket->TraceConnectWithoutContext
("CongestionWindow", MakeCallback (&CwndChange));
Connect Cwnd trace source and sink
Ptr<MyApp> app = CreateObject<MyApp> ();
app->Setup (ns3TcpSocket, sinkAddress, 1040, 1000,
DataRate ("1Mbps"));
nodes.Get (0)->AddApplication (app);
app->SetStartTime (Seconds (1.));
app->SetStopTime (Seconds (20.));
TCP application
devices.Get (1)->TraceConnectWithoutContext("PhyRxDrop",
MakeCallback (&RxDrop));
Simulator::Stop (Seconds(20));
Simulator::Run ();
Simulator::Destroy ();
Connect RxDrop trace source and sink
return 0;
}
Computer Network Laboratory
First project
 Simulation Topology
100Mbps, 5ms
10 senders and 10 receivers
1 UDP flow and 9 TCP flows
Simulation time: 60 seconds
UDP sending rate is increased by 1 Mbps on every 5 seconds
Computer Network Laboratory
Expected Simulation Result
 Trace with different queues
- Per-flow TCP Throughput
- Congestion window
- Routers’ queue size
 Queues
- DropTail
- RED
Computer Network Laboratory
Submission
 program file (or files)
- .cc (.h)
 Documents
- Source code with line-by-line comments
- Simulation results
Computer Network Laboratory