NS-2 Tutorial

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NS-2 Tutorial
Choe, Hyun Jung (Stella) Spring 2008 High
Performance Networks Department of Computer
Science and EngineeringThe University of Texas
at Arlington
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Outline

• NS-2 Overview
• How to Run NS-2
• How to Program
• Simulation Examples
• Project Overview
• Q A

3
NS-2 Overview
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What is NS-2?

• VINT Project
• UC Berkeley, LBL, USC/ISI, and Xerox PARC
• Goals
• Support networking research and education
• Freely distributed, open source
• Share code, protocols, models, etc
• a Discrete Event Simulator
• Link layer and up
• Wired and Wireless

5
NS Models

• Wired
• Routing DV, LS, PIM-SM etc.
• Transportation TCP and UDP
• Traffic sources web, ftp, telnet, cbr,
  stochastic etc.
• Queuing disciplines drop-tail, RED, FQ, SFQ,
  DRR etc.
• QoS IntServ and Diffserv
• Emulation
• Wireless
• Ad hoc routing, mobile IP and Satellite
• Directed diffusion, sensor-MAC

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NS Architecture

• Object-oriented (C, OTcl)
• data / control separation
• C for data
• per packet processing, core of ns
• fast to run, detailed, complete control
• OTcl for control
• Simulation scenario configurations
• Periodic or triggered action
• Manipulating existing C objects
• fast to write and change

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OTcl and C The Duality
! OTcl (object variant of Tcl) and C share
class hierarchy !
8
NS Components
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Part II How to Run NS-2
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How to Run NS-2

• gamma2 server
• Version 2.30
• Please use /tmp for your trace files (not codes)
  (later)
• xdisplay for graphical results
• If you want to install NS2 in your own PC
• Current release ns-2.31, Mar 10, 2007)
• http//www.isi.edu/nsnam/ns/ns-build.html
• Platforms
• Most Unix and Linux
• Windows and Mac

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How to Setup Path

• ls a
• .cshrc
• setenv LD_LIBRARY_PATH /opt/ns-allinone-2.30/
• .bash_profile
• export PATH/opt/ns-allinone-2.30/binPATH
• export LD_LIBRARY_PATH/opt/ns-allinone-2.30/otcl-
  1.12/opt/ns-allinone-2.30/libLD_LIBRARY_PATH
• export TCL_LIBRARY/opt/ns-allinone-2.30/tcl8.4.13
  /library

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gamma /tmp

• for Temporary Usage only
• Do Not save your scripts under /tmp
• Use Your Own directory
• mkdir /tmp/your_dir/
• Example
• set nf open /tmp/your_dir/out.nam w

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How to Install NS-2 (Under Windows)

• http//nsnam.isi.edu/nsnam/index.php/Running_Ns_an
  d_Nam_Under_Windows_9x/2000/XP_Using_Cygwin
• Cygwin-1.3.12 or later required
• Select UNIX text type
• to check current mode, type mount grep
  textmode
• C\Cygwin (not C\Program Files\Cygwin)
• Install ltX11gt and ltDevelgt Categories (next
  page) and others (e.g., vim) in ltEditorgt
• Download NS-2 under Cygwin (E.g., under
  /usr/local/)
• tar zxvf ns-allinone-2.2x.x.tar.gz
• cd ns-allinone-2.2x
• ./install

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Error?

• error near unexpected token )'
• ./configure line 7624 OSF)'
• tcl8.3.2 configuration failed! Exiting ...
• Tcl is not part of the ns project. Please see
  www.Scriptics.com
• to see if they have a fix for your platform.
• Remove only if there are two at the end of
  relid
• find . xargs -n 1 grep -H relid\
• Others
• http//ns-2.blogspot.com/2006/05/problem-in-insta
  lling-ns-2292-allinone.html
• http//www.isi.edu/nsnam/ns/ns-cygwin-old.html

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How to Use Cygwin-X

• http//xfree86.cygwin.com/docs/ug//usr/X11R6/
• Run /usr/X11R6/bin/startxwin.bat
• sh /usr/X11R6/bin/startxwin.sh
• cp /etc/X11/xinit/xinitrc /.xinitrc
• PATHPATH/usr/X11R6/bin
• startx

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NS-2 Directory Structure
/opt/ns-allinone-2.30/
ns-allinone
...
TK8.4.13
OTcl
tclcl
Tcl8.4.13
ns-2
nam-1.12
C code
...
tcl
ex
test
mcast
lib
...
examples
validation tests
OTcl code
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Part III How to Program
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Basic Tcl Programming

• set b 0
• b 0 in C
• set x b
• set x expr a b
• http//www-sop.inria.fr/maestro/personnel/Eitan.
  Altman/COURS-NS/n3.pdf

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Basic Tcl

• Command arg1 arg2 arg3
• set a 43
• set b 27
• proc test a b
• set c expr a b
• set d expr expr a - b c
• for set k 0 k lt 10 incr k
• if k lt 5
• puts k lt 5, pow expr pow(d, k)
• else
• puts k gt 5, mod expr d k

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Elements of NS-2

• Create the event scheduler
• Turn on tracing
• Create network
• Setup routing
• Insert errors
• Create transport connection
• Create traffic
• Transmit application-level data

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How to Simulate

• Create event scheduler
• set ns new Simulator
• Schedule events
• ns at lttimegt lteventgt
• lteventgt
• any legitimate ns/tcl commands
• ns at 5.0 finish
• Start scheduler
• ns run
• TclCL
• C and OTcl linkage
• glue library that makes it easy to share
  functions, variables, etc

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Example helloWorld.tcl

• set ns new Simulator
• ns at 1 puts \Hello World!\
• ns at 1.5 exit
• ns run
• ns simple.tcl
• Hello World!

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Creating Network

• Nodes
• set n0 ns node
• set n1 ns node
• Links and queuing
• ns duplex-link n0 n1 ltbandwidthgt ltdelaygt
  ltqueue_typegt
• ltqueue_typegt DropTail, RED, CBQ, FQ, SFQ, DRR
• ns duplex-link-op no n1 OPTIONS

n0
n1
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Setup Routing

• Unicast
• ns rtproto lttypegt
• lttypegt Static, Session, DV, cost, multi-path
• Multicast
• ns multicast (right after new Simulator)
• ns mrtproto lttypegt
• lttypegt CtrMcast, DM, ST, BST

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Creating Connection UDP

• UDP
• set udp new Agent/UDP
• set null new Agent/Null
• ns attach-agent n0 udp
• ns attach-agent n1 null
• ns connect udp null

UDP
null
n0
n1
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Creating Traffic On Top of UDP

• CBR
• set src new Application/Traffic/CBR
• src attach-agent udp0
• Exponential or Pareto on-off
• set src new Application/Traffic/Exponential
• set src new Application/Traffic/Pareto
• src attach-agent udp0

CBR
UDP
null
n0
n1
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Structure of a Unicast Node
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Structure of a Simplex Link
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Creating Connection TCP

• TCP
• set tcp new Agent/TCP
• set tcpsink new Agent/TCPSink
• ns attach-agent n0 tcp
• ns attach-agent n1 tcpsink
• ns connect tcp tcpsink

TCP
sink
n0
n1
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Creating Traffic On Top of TCP

• FTP
• set ftp new Application/FTP
• ftp attach-agent tcp
• Telnet
• set telnet new Application/Telnet
• telnet attach-agent tcp

FTP
TCP
sink
n0
n1
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A simulation example
ftp
W32
tcp
sink
n0
n4
5Mb, 15ms
n2
n3
10Mb,2ms
10Mb,2ms
n1
n5
sink
tcp
ftp
W32
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TCP Agents

• ns has several variants of TCP available
• -- Agent/TCP/Tahoe a tahoe'' TCP sender
• -- Agent/TCP/Reno a Reno'' TCP sender
• -- Agent/TCP/NewReno Reno with a modification
• -- Agent/TCP/Sack1 TCP with selective repeat
  (follows RFC2018)
• -- Agent/TCP/Vegas TCP Vegas
• -- Agent/TCP/Fack Reno TCP with forward
  acknowledge ment''
• The oneway TCP receiving agents currently
  supported are
• -- Agent/TCPSink TCP sink with one ACK per
  packet
• -- Agent/TCPSink/DelAck TCP sink with
  configurable delay per ACK
• -- Agent/TCPSink/Sack1 selective ACK sink
  (follows RFC2018)
• -- Agent/TCPSink/Sack1/DelAck Sack1 with DelAck
• The twoway experimental sender currently supports
  only a Reno form of TCP
• -- Agent/TCP/FullTcp

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TCP Agent Parameters

• Agent/TCP set tcpTick 0.1 timer granularity
  in sec (.1 is NONST ANDARD)
• Agent/TCP set maxrto 64 bound on RTO
  (seconds)
• Agent/TCP set dupacks 0 duplicate ACK counter
  
• Agent/TCP set ack 0 highest ACK received
• Agent/TCP set cwnd 0 congestion window
  (packets)
• Agent/TCP set awnd 0 averaged cwnd
  (experimental)
• Agent/TCP set ssthresh 0 slowstat threshold
  (packets)
• Agent/TCP set rtt 0 rtt sample
• Agent/TCP set srtt 0 smoothed (averaged) rtt
• Agent/TCP set rttvar 0 mean deviation of rtt
  samples
• Agent/TCP set backoff 0 current RTO backoff
  factor
• Agent/TCP set maxseq 0 max (packet) seq
  number sent

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Tracing and Monitoring I

• Trace packets on all links
• Open the NAM trace file Open the Trace file
• set nf open out.nam w set tf open
  out.tr w
• ns namtrace-all nf ns
  trace-all tf
• Must appear immediately after creating scheduler
• Turn on tracing on specific links
• ns trace-queue n0 n1
• ns namtrace-queue n0 n1
• Event tracing (support TCP right now)
• Record event in trace file ns eventtrace-all

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Tracing and Monitoring II
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Tracing and Monitoring III

• Queue monitor
• set qmon ns monitor-queue n0 n1 q_f
  sample_interval
• Get statistics for a queue
• qmon set pdrops_
• Record to trace file as an optional
• 29.000000000000142 0 1 0.0 0.0 4 4 0 1160 1160
  0
• Flow monitor
• set fmon ns_ makeflowmon Fid
• ns_ attach-fmon slink fmon
• fmon set pdrops_

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Tracing and Monitoring IV

• Variable tracing in nam
• Agent/TCP set nam_tracevar_ true
• tcp tracevar srtt_
• tcp tracevar cwnd_
• Monitor agent variables in nam
• ns add-agent-trace tcp tcp
• ns monitor-agent-trace tcp
• srm0 tracevar cwnd_
• ns delete-agent-trace tcp

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Visualization Tools

• nam-1 (Network AniMator Version 1)
• Packet-level animation
• Well supported by ns
• xgraph
• Conversion from ns trace to xgraph format

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xgraph

• The xgraph program draws a graph on an X display
  given data read from either data files.
• To run it xgraph dataFileName
• You can save the hardcopy of the graph as a
  postscript file.
• Xgraph is available on gamma
• /opt/ns-allinone-2.30/xgraph-12.1

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nam

• Basic visualization
• Topology layout
• Animation control
• Synchronous replay
• Fine-tune layout
• TCP/SRM visualization
• Editor generate ns simulation scripts

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ns?nam Interface

• Color
• Node manipulation
• Link manipulation
• Topology layout
• Protocol state
• Misc

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nam Interface Color

• Color mapping
• ns color 1 red
• ns color 2 blue
• ns color 3 chocolate
• Color ? flow id association
• tcp0 set fid_ 1 red packets
• tcp1 set fid_ 2 blue packets

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nam Interface Nodes

• Color
• node color red
• Shape (cant be changed after sim starts)
• node shape box circle, box, hexagon
• Marks (concentric shapes)
• ns at 1.0 n0 add-mark m0 blue box
• ns at 2.0 n0 delete-mark m0
• Label (single string)
• ns at 1.1 n0 label \web cache 0\

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nam Interfaces Links

• Color
• ns duplex-link-op n0 n1 color "green"
• Label
• ns duplex-link-op n0 n1 label "abced"
• Dynamics (automatically handled)
• ns rtmodel Deterministic 2.0 0.9 0.1 n0 n1
• Asymmetric links not allowed

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nam Interface Topo Layout

• Manual layout specify everything
• ns duplex-link-op n(0) n(1) orient right
• ns duplex-link-op n(1) n(2) orient right
• ns duplex-link-op n(2) n(3) orient right
• ns duplex-link-op n(3) n(4) orient 60deg
• If anything missing ? automatic layout

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nam Interface Protocol State

• Monitor values of agent variables
• ns add-agent-trace srm0 srm_agent0
• ns monitor-agent-trace srm0
• srm0 tracevar C1_
• srm0 tracevar C2_
• ns delete-agent-trace tcp1

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nam Interface Misc

• Annotation
• Add textual explaination to your sim
• ns at 3.5 "ns trace-annotate \packet drop\"
• Set animation rate
• ns at 0.0 "ns set-animation-rate 0.1ms"

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Summary Generic Script Structure

• set ns new Simulator
• Turn on tracing
• Create topology
• Setup packet loss, link dynamics
• Create routing agents
• Create
• - multicast groups
• - protocol agents
• - application and/or setup traffic sources
• Post-processing procs
• Start simulation