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• tcl.enter(TclObject* o) will insert a pointer to the TclObject o into the hash table.It is used by TclClass::create_shadow() to insert an object into the table, when that object is created.• tcl.lookup(char* s) will retrieve the TclObject with the name s.It is used by TclObject::lookup().• tcl.remove(TclObject* o) will delete references to the TclObject o from the hash table.It is used by TclClass::delete_shadow() to remove an existing entry from the hash table, when that object isdeleted.These functions are used internally by the class TclObject and class TclClass.3.3.6 Other Operations on the InterpreterIf the above methods are not sufficient, then we must acquire the handle to the interpreter, and write our own functions.• tcl.interp(void) returns the handle to the interpreter that is stored within the class Tcl.3.4 Class TclObjectclass TclObject is the base class for most of the other classes in the interpreted and compiled hierarchies. Every objectin the class TclObject is created by the user from within the interpreter. An equivalent shadow object is created in the compiledhierarchy. The two objects are closely associated with each other. The class TclClass, described in the next section, containsthe mechanisms that perform this shadowing.In the rest of this document, we often refer to an object as a TclObject 1 . By this, we refer to a particular object that is eitherin the class TclObject, or in a class that is derived from the class TclObject. If it is necessary, we will explicitly qualifywhether that object is an object within the interpreter, or an object within the compiled code. In such cases, we will use theabbreviations “interpreted object”, and “compiled object” to distinguish the two. and within the compiled code respectively.Differences from ns v1 Unlike ns v1, the class TclObject subsumes the earlier functions of the NsObject class. It thereforestores the interface variable bindings (Section 3.4.2) that tie OTcl instance variables in the interpreted object to correspondingC++ member variables in the compiled object. The binding is stronger than in ns v1 in that any changes to the OTcl variablesare trapped, and the current C++ and OTcl values are made consistent after each access through the interpreter. The consistencyis done through the class InstVar (Section 3.8). Also unlike ns v1, objects in the class TclObject are no longer stored asa global link list. Instead, they are stored in a hash table in the class Tcl (Section 3.3.5).Example configuration of a TclObjectAgent/SRM/Adaptive).The following example illustrates the configuration of an SRM agent (classset srm [new Agent/SRM/Adaptive]$srm set packetSize_ 1024$srm traffic-source $s01 In the latest release of ns and ns/tclcl, this object has been renamed to SplitObjefct, which more accurately reflects its nature of existence. However,for the moment, we will continue to use the term TclObject to refer to these objects and this class.23
By convention in ns, the class Agent/SRM/Adaptive is a subclass of Agent/SRM, is a subclass of Agent, is a subclass ofTclObject. The corresponding compiled class hierarchy is the ASRMAgent, derived from SRMAgent, derived from Agent,derived from TclObject respectively. The first line of the above example shows how a TclObject is created (or destroyed)(Section 3.4.1); the next line configures a bound variable (Section 3.4.2); and finally, the last line illustrates the interpretedobject invoking a C++ method as if they were an instance procedure (Section 3.4.4).3.4.1 Creating and Destroying TclObjectsWhen the user creates a new TclObject, using the procedures new{} and delete{}; these procedures are defined in~tclcl/tcl-object.tcl. They can be used to create and destroy objects in all classes, including TclObjects. 2 . In this section,we describe the internal actions executed when a TclObject is created.Creating TclObjects By using new{}, the user creates an interpreted TclObject. the interpreter will execute the constructorfor that object, init{}, passing it any arguments provided by the user. ns is responsible for automatically creating thecompiled object. The shadow object gets created by the base class TclObject’s constructor. Therefore, the constructor forthe new TclObject must call the parent class constructor first. new{} returns a handle to the object, that can then be used forfurther operations upon that object.The following example illustrates the Agent/SRM/Adaptive constructor:Agent/SRM/Adaptive instproc init args {eval $self next $args$self array set closest_ "requestor 0 repairor 0"$self set eps_ [$class set eps_]}The following sequence of actions are performed by the interpreter as part of instantiating a new TclObject. For ease ofexposition, we describe the steps that are executed to create an Agent/SRM/Adaptive object. The steps are:1. Obtain an unique handle for the new object from the TclObject name space. The handle is returned to the user. Mosthandles in ns have the form _o〈NNN〉, where 〈NNN〉 is an integer. This handle is created by getid{}. It can beretrieved from C++ with the name(){} method.2. Execute the constructor for the new object. Any user-specified arguments are passed as arguments to the constructor.This constructor must invoke the constructor associated with its parent class.In our example above, the Agent/SRM/Adaptive calls its parent class in the very first line.Note that each constructor, in turn invokes its parent class’ constructor ad nauseum. The last constructor in ns is theTclObject constructor. This constructor is responsible for setting up the shadow object, and performing other initializationsand bindings, as we explain below. It is preferable to call the parent constructors first before performing theinitializations required in this class. This allows the shadow objects to be set up, and the variable bindings established.3. The TclObject constructor invokes the instance procedure create-shadow{} for the class Agent/SRM/Adaptive.4. When the shadow object is created, ns calls all of the constructors for the compiled object, each of which may establishvariable bindings for objects in that class, and perform other necessary initializations. Hence our earlier injunction thatit is preferable to invoke the parent constructors prior to performing the class initializations.5. After the shadow object is successfully created, create_shadow(void)2 As an example, the classes Simulator, Node, Link, or rtObject, are classes that are not derived from the class TclObject. Objects in these classes are not,therefore, TclObjects. However, a Simulator, Node, Link, or route Object is also instantiated using the new procedure in ns.24
Page 6 and 7: 18 Radio Propagation Models 17718.1
Page 8 and 9: 30 Multicast Routing 25130.1 Multic
Page 10 and 11: 38.2.5 An example . . . . . . . . .
Page 12 and 13: X Other 40347 Educational use of NS
Page 14: # so, we lied. now, we define the t
Page 17 and 18: Chapter 2Undocumented FacilitiesNs
Page 19 and 20: Part IInterface to the Interpreter1
Page 21 and 22: • if you can do what you want by
Page 23: • tcl.result(const char* s)Pass t
Page 27 and 28: $object set bwvar 1500kb$object set
Page 29 and 30: For a C++ variable to be traceable,
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Page 33 and 34: class Packet {......static int hdrl
Page 35 and 36: The actual arguments passed by the
Page 37 and 38: class TclClass (Section 3.5) define
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Page 41 and 42: 4.2.2 the heap schedulerThe heap sc
Page 43 and 44: 4.4 Commands at a glanceSynopsis:ns
Page 45 and 46: $ns_ dumpqCommand for dumping event
Page 47 and 48: NODEPortClassifierAgentAgentAddrCla
Page 49 and 50: The Node instance variable, entry_,
Page 51 and 52: The default values for all the abov
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Page 67 and 68: 6.2 ConnectorsConnectors, unlink cl
Page 69 and 70: $ns_ link-lossmodel This function
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7.3 Different types of Queue object
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maxidle_ is the maximum amount of t
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dst_ The destination address of pac
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7.5.2 ConfigurationRunning a JoBS s
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mean_pkt_size_ Used to set the expe
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Demarker objects$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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32.4 Hierarchical Routing with Sess
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Chapter 33UDP Agents33.1 UDP Agents
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Chapter 34TCP AgentsThis section de
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set ns [new Simulator]set node1 [$n
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34.2.1 The Base TCP SinkThe base TC
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Agent/TCP/FullTcp set dupseg_fix_ t
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34.5 Tracing TCP DynamicsThe behavi
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Chapter 35SCTP AgentsThis chapter d
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Figure 35.1: Example of a Multihome
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Note: the actual value of these tra
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1.526624 1 4 sctp 1500 -------D 0 1
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$ns at 5.0 "finish"$ns run35.5.2 Mu
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Chapter 36Agent/SRMThis chapter des
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36.1.2 Other Configuration Paramete
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3.6274 n 0 m r 1 type repair servi
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3.6029 n 3 m r 2 Q NTIMER at 3.730
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36.4 Loss Detection—The Class SRM
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same packet. The repair objet does
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}hdr_asrm* seh = (hdr_asrm*) p->acc
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set grp [Node allocaddr]$srm set ds
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#set up the multicast routingDM set
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37.3 Architecture of the PLM Protoc
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We add in void PLMLossMonitor::recv
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Part VIApplication330
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Traffic generatorsApplication/Traff
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• recv(int nbytes)—Announces th
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1. EXPOO_Traffic—generates traffi
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set src [new Agent/UDP]set sink [ne
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Application FTP FTP objects produce
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send_data(ADU)Application(HttpApp,
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39.1.4 Transmitting user data over
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and teardown of connections. Only O
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TclObjectPagePoolPagePool/CompMathP
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PagePool/ProxyTrace takes these two
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}int id_; // object IDWebTrafSessio
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An Http/Server object waits for inc
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set tmp [new RandomVariable/Exponen
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Object Type Event Type Explaination
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Chapter 40Worm ModelIn this chapter
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$w local-p 0.5Following are some co
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(nsnode) clientcloudPackM ime(nsnod
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HTTP responsesclients servers Delay
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41.5 Commands at a GlanceThe follow
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• HTTP response size (bytes)• s
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Chapter 42Session-level Packet Dist
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42.1.2 Inserting a Loss ModuleWhen
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Delay and Loss Modules Each receive
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Chapter 43Asim: approximate analyti
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set n(1) [$ns node]set link(0:1) [$
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Part VIIIEmulation382
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When using the emulation mode, a sp
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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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