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In the configuration script, the first five lines of code allocates two new FullTcp agents, attaches them to the correct nodes,and "connects" them together (assigns the correct destination addresses to each agent). The next two lines configure theTCP agents further, placing one of them in LISTEN mode. Next, ftp1 is defined as a new FTP Application, and theattach-agent method is called in C++ (app.cc).The ftp1 application is started at time 0:Application/FTP instproc start {} {[$self agent] send -1; # Send indefinitely}Alternatively, the FTP application could have been implemented in C++ as follows:void FTP::start(){agent_->send(-1);}// Send indefinitelySince the FTP application does not make use of callbacks, these functions are null in C++ and no OTcl callbacks are made.38.3 The class TrafficGeneratorTrafficGenerator is an abstract C++ class defined as follows:class TrafficGenerator : public Application {public:TrafficGenerator();virtual double next_interval(int &) = 0;virtual void init() {}virtual double interval() { return 0; }virtual int on() { return 0; }virtual void timeout();virtual void recv() {}virtual void resume() {}protected:virtual void start();virtual void stop();double nextPkttime_;int size_;int running_;TrafficTimer timer_;};The pure virtual function next_interval() returns the time until the next packet is created and also sets the size in bytesof the next packet. The function start() calls init(void) and starts the timer. The function timeout() sends a packet andreschedules the next timeout. The function stop() cancels any pending transmissions. Callbacks are typically not used fortraffic generators, so these functions (recv, resume) are null.Currently, there are four C++ classes derived from the class TrafficGenerator:335
1. EXPOO_Traffic—generates traffic according to an Exponential On/Off distribution. Packets are sent at a fixed rateduring on periods, and no packets are sent during off periods. Both on and off periods are taken from an exponentialdistribution. Packets are constant size.2. POO_Traffic—generates traffic according to a Pareto On/Off distribution. This is identical to the ExponentialOn/Off distribution, except the on and off periods are taken from a pareto distribution. These sources can be used togenerate aggregate traffic that exhibits long range dependency.3. CBR_Traffic—generates traffic according to a deterministic rate. Packets are constant size. Optionally, somerandomizing dither can be enabled on the interpacket departure intervals.4. TrafficTrace—generates traffic according to a trace file. Each record in the trace file consists of 2 32-bit fields innetwork (big-endian) byte order. The first contains the time in microseconds until the next packet is generated. Thesecond contains the length in bytes of the next packet.These classes can be created from OTcl. The OTcl classes names and associated parameters are given below:Exponential On/Off An Exponential On/Off object is embodied in the OTcl class Application/Traffic/Exponential. Themember variables that parameterize this object are:packetSize_burst_time_idle_time_rate_the constant size of the packets generatedthe average “on” time for the generatorthe average “off” time for the generatorthe sending rate during “on” timesHence a new Exponential On/Off traffic generator can be created and parameterized as follows:set e [new Application/Traffic/Exponential]$e set packetSize_ 210$e set burst_time_ 500ms$e set idle_time_ 500ms$e set rate_ 100kNOTE: The Exponential On/Off generator can be configured to behave as a Poisson process by setting the variable burst_time_to 0 and the variable rate_ to a very large value. The C++ code guarantees that even if the burst time is zero, at least onepacket is sent. Additionally, the next interarrival time is the sum of the assumed packet transmission time (governed by thevariable rate_) and the random variate corresponding to idle_time_. Therefore, to make the first term in the sum verysmall, make the burst rate very large so that the transmission time is negligible compared to the typical idle times.Pareto On/Off A Pareto On/Off object is embodied in the OTcl class Application/Traffic/Pareto. The member variablesthat parameterize this object are:packetSize_burst_time_idle_time_rate_shape_the constant size of the packets generatedthe average "on" time for the generatorthe average "off" time for the generatorthe sending rate during "on" timesthe "shape" parameter used by the pareto distributionA new Pareto On/Off traffic generator can be created as follows:336
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18 Radio Propagation Models 17718.1
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30 Multicast Routing 25130.1 Multic
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38.2.5 An example . . . . . . . . .
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X Other 40347 Educational use of NS
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# so, we lied. now, we define the t
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Chapter 2Undocumented FacilitiesNs
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Part IInterface to the Interpreter1
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• if you can do what you want by
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• tcl.result(const char* s)Pass t
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By convention in ns, the class Agen
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$object set bwvar 1500kb$object set
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For a C++ variable to be traceable,
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3.5 Class TclClassThis compiled cla
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class Packet {......static int hdrl
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The actual arguments passed by the
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class TclClass (Section 3.5) define
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Chapter 4The Class SimulatorThe ove
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4.2.2 the heap schedulerThe heap sc
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4.4 Commands at a glanceSynopsis:ns
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$ns_ dumpqCommand for dumping event
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NODEPortClassifierAgentAgentAddrCla
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The Node instance variable, entry_,
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The default values for all the abov
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The classify() method is pure virtu
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};The class imposes no direct seman
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flow-specific queuing disciplines a
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5.5 Routing Module and Classifier O
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Module NameRtModule/BaseRtModule/Mc
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$node neighborsThis returns the lis
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Linkhead_enqT_queue_ deqT_ link_ tt
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6.2 ConnectorsConnectors, unlink cl
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$ns_ link-lossmodel This function
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Chapter 7Queue Management and Packe
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}}}void Queue::resume(){Packet* p =
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7.3 Different types of Queue object
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maxidle_ is the maximum amount of t
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dst_ The destination address of pac
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7.5.2 ConfigurationRunning a JoBS s
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mean_pkt_size_ Used to set the expe
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Demarker objects$q trace-file This
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The recv() method overrides the bas
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9.2 ImplementationThe procedures an
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Average sending rateTSW window leng
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The following command adds an entry
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$qCE configQ 0 1 10 20 0.10Note tha
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Chapter 10AgentsAgents represent en
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CtrMcast/EncapCtrMcast/DecapMessage
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}bind("windowOption_", &wnd_option_
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hdr_flags* nf = (hdr_flags*)npkt->a
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public:ECHO_Timer(ECHO_Agent *a) :
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10.6.4 Using the agent through OTcl
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State Variables are:dupacks_ Number
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$agent attach-tbf Attaches a token
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(void)Scheduler::instance().schedul
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* outstanding, cancel it.*/void Tcp
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Chapter 12Packet Headers and Format
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method is now obsolete; its usage i
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Packethdrsize_next_bits()points to
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the system’s memory allocator. In
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}incr hdrlen_ $incrreturn $baseFrom
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Chapter 13Error ModelThis chapter d
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SimpleLink::errormodule argsSimulat
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This is a simple example of how to
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Higher LayersNode 1Node 2. . .Node
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};void recv(Packet* p, Handler*);vi
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and the frame type. It then passes
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$ll_ set delay_ $delay$ll_ set band
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14.10 Commands at a glanceThe follo
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15.2.1 Default Hierarchical Setting
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Chapter 16Mobile Networking in nsTh
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entry_addrdemuxIP addressdefaulttar
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16.1.2 Creating Node movementsThe m
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set netif $netif_($t)set mac $mac_(
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the hardware address of a packet’
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destined to itself to the port dmux
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switch(ch->ptype()) {case PT_MAC:br
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16.1.7 Revised format for wireless
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Packet info at "Application level"
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The main problem facing the wired-c
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target_target_encapsulatorreg_agent
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why: This avoids header clashes bet
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This command is used to create a Go
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Chapter 17Satellite Networking in n
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in counter-rotating planes (where t
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• Position/Sat/Geo A geostationar
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$ns add-isl $ltype $node1 $node2 $b
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$satrouteobject_ compute_routeswher
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This will add an error model to the
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lh_firstnameobj‘‘name’’ is
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from routing agentto Node->entrySat
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$satnode add-isl This method c
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set prop [new Propagation/FreeSpace
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18.3.2 Using shadowing modelBefore
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Chapter 19Energy Model in nsEnergy
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Chapter 20Directed DiffusionThe dir
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However if we have a large and dens
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yr application in the ns context. T
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value of opt(pre-stop) is usually t
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21.2 Implementation of XCP in NSIn
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the persistent queue length in the
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Thruput2 0.054024 60000residue_pos_
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Chapter 22DelayBox: Per-Flow Delay
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$ns attach-agent $n_sink $sink# mak
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Chapter 23Changes made to the IEEE
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Part IIISupport214
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endenddocument pargvcPrint out argc
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24.4.2 Memory Conservation TipsSome
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Chapter 25Mathematical SupportThe s
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set run [lindex $argv 0]}if {$run <
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}$sizeRNG next-substream# print the
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protected:RNG* rng_;};Classes deriv
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ns-random is implemented in ~ns/mis
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Chapter 26Trace and Monitoring Supp
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The monitor-queue function is const
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also used to accumulate packet drop
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}name,th->size(),flags,iph->flowid(
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PT_TORA,PT_DSR,PT_AODV,// insert ne
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The QueueMonitor class is not deriv
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$ns_ trace-all This is the command
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Chapter 27Test Suite SupportThe ns
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... ...}$ns_ at $opt(stop).1 "$self
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Example: To enable debugging in Que
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Chapter 29Unicast RoutingThis secti
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Asymmetric Routing Asymmetric routi
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class RouteLogic This class defines
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— The procedure init-all{} is a g
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Global Actions Once the detailed ac
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This dumps next hop information in
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$ns mrtproto ST;# specify shared tr
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Dense Mode The Dense Mode protocol
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and unique label (id). Thus, “inc
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add-iif{ifid link},add-oif{link if}
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CtrMcastComp is the centralised mul
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$ns_ mrtproto This command specifi
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Chapter 31Network DynamicsThis chap
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v 0.8123 link-up 3 5v 0.8123 link-u
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The first argument is the time at w
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$ns_ rtmodel This command defines
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$ns set-address-format hierarchical
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Page 297 and 298: 34.5 Tracing TCP DynamicsThe behavi
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Page 319 and 320: same packet. The repair objet does
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Page 333 and 334: Traffic generatorsApplication/Traff
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Page 361 and 362: Chapter 40Worm ModelIn this chapter
Page 363 and 364: $w local-p 0.5Following are some co
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Page 367 and 368: HTTP responsesclients servers Delay
Page 369 and 370: 41.5 Commands at a GlanceThe follow
Page 371 and 372: • HTTP response size (bytes)• s
Page 373 and 374: Chapter 42Session-level Packet Dist
Page 375 and 376: 42.1.2 Inserting a Loss ModuleWhen
Page 377 and 378: Delay and Loss Modules Each receive
Page 379 and 380: Chapter 43Asim: approximate analyti
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Page 383 and 384: Part VIIIEmulation382
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set intf [$pf1 open readonly]puts "
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puts "install nets into taps..."$a0
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Chapter 45Nam45.1 IntroductionNam i
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• Button 6 (Chevron logo) - Close
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Second, when dealing with randomly
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dst_portaddr,seqno,flags,sname);A n
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• up• down• right• left•
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46.1.7 Agent TracingAgent trace eve
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v -t 1.0 -e node_tclscript 2 "Echo
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If nam ever gets to the end of an e
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l :link-t time-s source id-d des
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E :D :P :a :session enqueue-t time
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v :V :N :W :g :A :c :q :execute tcl
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$ns duplex-link-op orient right$ns
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Chapter 47Educational use of NS and
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Bibliography[1] C. Alaettinoğlu, A
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