Introduction to NS-3 Part - 2

NS-3
2 April 2012

Simulator Cradle)
MPI (Message Passing Interface)
EMU (Emulation)

flow metrics from arbitrary simulations?”
Existing solutions do not solve this

problem effectively

The Flow Monitor solves the problem
Requires significant less programming time than NS-3 callback based tracing
A lot more efficient than ascii tracing

More data output methods (e.g. database and binary file)

More options to control level of detail stored in memory

Monitor multicast/broadcast flows

flow from the point of view of the receiver
timeFirstRxPacket, timeLastRxPacket

begin and end times of the flow from the point of view of the receiver
delaySum, jitterSum sum of delay and jitter values
txBytes, txPackets number of transmitted bytes and packets
rxBytes, rxPackets number of received bytes and packets
lostPackets number of definitely lost packets
timesForwarded the number of times a packet has been reportedly forwarded, summed for all packets in the flow
delayHistogram, jitterHistogram, packetSizeHistogram Histogram versions for the delay, jitter, and packet sizes, respectively
packetsDropped, bytesDropped discriminates the losses by a reason code
DROP NO ROUTE no IPv4 route found for a packet
DROP TTL EXPIRE a packet was dropped due to an IPv4 TTL field decremented and reaching zero
DROP BAD CHECKSUM a packet had a bad IPv4 header checksum and had to be dropped

FlowMonirot class and install probes to all nodes
Ptr monitor =

flowmon.InstallAll();

Configure histogram parameters
Monitor->SetAttribute (”DelayBinWidth”, DoubleValue(0.001));
Monitor->SetAttribute (”JitterBinWidth”,DoubleValue (0.001));

Run simulation
Simulator::Run ();

Write results into an XML file
monitor->SerializeToXmlFile (”results.xml”,True,True);

limit memory leaks
Or “pass by value” or “pass by reference

to const” where appropriate
A “smart pointer” behaves like a normal pointer (syntax) but does not lose memory when reference count goes to zero
Use them like built-in pointers:
Ptr p = CreateObject ();
p->method ();

attached a packet
Tags are keyed by the a structure type

itself
E.g.:
Ptr p;
MyTag tag;
p->AddTag (tag);
p->PeekTag (tag);

New tag types are defined similarly to header types
Tags can be used to:
Attach context information to a packet
Example: NetDevice attaches destination MAC address when queueing, retrieves it when dequeuing for transmission
Convey additional information across layers

false
Includes source file name and line number
Unconditional Breakpoints: NS_BREAKPOINT ();
Forces

an unconditional breakpoint, compiled in
Debug Logging (not to be confused with tracing!)
Purpose
Used to trace code execution logic
For debugging, not to extract results!
Properties
NS_LOG* macros work with C++ IO streams
E.g.: NS_LOG_UNCOND (”I have received ” << p->GetSize () << ” bytes”);
NS_LOG macros evaluate to nothing in optimized builds
When debugging is done, logging does not get in the way of execution performance

messages
NS_LOG_DEBUG (...): rare ad-hoc debug messages
NS_LOG_INFO (...): informational messages (eg.

banners)
NS_LOG_FUNCTION (...):function tracing
NS_LOG_PARAM (...): parameters to functions
NS_LOG_LOGIC (...): control flow tracing within functions
Logging ”components”
Logging messages organized by components
Usually one component is one .cc source file
NS_LOG_COMPONENT_DEFINE ("OlsrAgent");
Displaying log messages. Two ways:
Programatically:
LogComponentEnable("OlsrAgent", LOG_LEVEL_ALL);
From the environment:
NS_LOG="OlsrAgent" ./my-program

this as input and create the animation.
netanim, pyviz, and nam

for ns-3

be animated, but topology will be shown
Complete redesign using

the QGraphics framework
Packet statistics with filter
Node position statistics with node trajectory (path of a mobile node) plotting
Improved window re-sizing and zooming

http://www.nsnam.org/wiki/index.php/NetAnim

the NS3, just run the create-module.py script that will create

the basic structure of the module (examples, helper, test, model and the appropriate wscript ).
As of ns-3.13 there is no need to add the module in ns3 wscript, it is done automatically.

Usage:
./create-module.py [options] modulename

Then clean the project, configure and re-build it
%./waf distclean
%./waf configure
%./waf

real world TCP/IP network stacks to be used inside a

network simulator

http://www.nsnam.org/wiki/index.php/Network_Simulation_Cradle_Integration

distributed applications
MPI simulator (as of ns-3.8)
Nodes in the simulation assigned

different System Ids
Nodes with different System Ids run on different cluster machines
Nodes on different machines may communication using p2p links only

Node 1
SystemId 1

Node 2
SystemId 1

Node 3
SystemId 2

Node 5
SystemId 2

Node 4
SystemId 2

Point-to-point
Link
(simulation
and real world)

Node 0
SystemId 1

scheduler, and support for two modes of emulation
GlobalValue::Bind (“SimulatorImplementationType”, StringValue

(“ns3::RealTimeSimulatorImpl”));

slides