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The following member functions are also defined by the class Agent, but are intended to be over-ridden by classes derivingfrom Agent:void timeout(timeout number)void recv(Packet*, Handler*)subclass-specific time out methodreceiving agent main receive pathThe allocpkt() method is used by derived classes to create packets to send. The function fills in the following fields inthe common packet header (Section 12): uid, ptype, size, and the following fields in the IP header: src, dst,flowid, prio, ttl. It also zero-fills in the following fields of the Flags header: ecn, pri, usr1, usr2. Anypacket header information not included in these lists must be must be handled in the classes derived from Agent.The recv() method is the main entry point for an Agent which receives packets, and is invoked by upstream nodes whensending a packet. In most cases, Agents make no use of the second argument (the handler defined by upstream nodes).10.3 Protocol AgentsThere are several agents supported in the simulator. These are their names in OTcl:TCPTCP/RenoTCP/NewrenoTCP/Sack1TCP/FackTCP/FullTcpTCP/VegasTCP/Vegas/RBPTCP/Vegas/RBPTCP/AsymTCP/Reno/AsymTCP/Newreno/AsymTCPSinkTCPSink/DelAckTCPSink/AsymTCPSink/Sack1TCPSink/Sack1/DelAcka “Tahoe” TCP sender (cwnd = 1 on any loss)a “Reno” TCP sender (with fast recovery)a modified Reno TCP sender (changes fast recovery)a SACK TCP sendera “forward” SACK sender TCPa more full-functioned TCP with 2-way traffica “Vegas” TCP sendera Vegas TCP with “rate based pacing”a Reno TCP with “rate based pacing”an experimental Tahoe TCP for asymmetric linksan experimental Reno TCP for asymmetric linksan experimental Newreno TCP for asymmetric linksa Reno or Tahoe TCP receiver (not used for FullTcp)a TCP delayed-ACK receiveran experimental TCP sink for asymmetric linksa SACK TCP receivera delayed-ACK SACK TCP receiverUDPa basic UDP agentRTPRTCPan RTP sender and receiveran RTCP sender and receiverLossMonitora packet sink which checks for lossesIVS/SourceIVS/Receiveran IVS sourcean IVS receiver97
CtrMcast/EncapCtrMcast/DecapMessageMessage/PruneSRMSRM/AdaptiveTapNullrtProto/DVa “centralised multicast” encapsulatora “centralised multicast” de-encapsulatora protocol to carry textual messagesprocesses multicast routing prune messagesan SRM agent with non-adaptive timersan SRM agent with adaptive timersinterfaces the simulator to a live networka degenerate agent which discards packetsdistance-vector routing protocol agentAgents are used in the implementation of protocols at various layers. Thus, for some transport protocols (e.g. UDP) thedistribution of packet sizes and/or inter-departure times may be dictated by some separate object representing the demandsof an application. To this end, agents expose an application programming interface (API) to the application. For agents usedin the implementation of lower-layer protocols (e.g. routing agents), size and departure timing is generally dictated by theagent’s own processing of protocol messages.10.4 OTcl LinkageAgents may be created within OTcl and an agent’s internal state can be modified by use of Tcl’s set function and any Tclfunctions an Agent (or its base classes) implements. Note that some of an Agent’s internal state may exist only within OTcl,and is thus is not directly accessible from C++.10.4.1 Creating and Manipulating AgentsThe following example illustrates the creation and modification of an Agent in OTcl:set newtcp [new Agent/TCP];# create new object (and C++ shadow object)$newtcp set window_ 20 ;# sets the tcp agent’s window to 20$newtcp target $dest;# target is implemented in Connector class$newtcp set portID_ 1;# exists only in OTcl, not in C++10.4.2 Default ValuesDefault values for member variables, those visible in OTcl only and those linked between OTcl and C++ with bind areinitialized in the ~ns/tcl/lib/ns-default.tcl file. For example, Agent is initialized as follows:Agent set fid_ 0Agent set prio_ 0Agent set addr_ 098
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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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Page 49 and 50: The Node instance variable, entry_,
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Page 57 and 58: flow-specific queuing disciplines a
Page 59 and 60: 5.5 Routing Module and Classifier O
Page 61 and 62: Module NameRtModule/BaseRtModule/Mc
Page 63 and 64: $node neighborsThis returns the lis
Page 65 and 66: Linkhead_enqT_queue_ deqT_ link_ tt
Page 67 and 68: 6.2 ConnectorsConnectors, unlink cl
Page 69 and 70: $ns_ link-lossmodel This function
Page 71 and 72: Chapter 7Queue Management and Packe
Page 73 and 74: }}}void Queue::resume(){Packet* p =
Page 75 and 76: 7.3 Different types of Queue object
Page 77 and 78: maxidle_ is the maximum amount of t
Page 79 and 80: dst_ The destination address of pac
Page 81 and 82: 7.5.2 ConfigurationRunning a JoBS s
Page 83 and 84: mean_pkt_size_ Used to set the expe
Page 85 and 86: Demarker objects$q trace-file This
Page 87 and 88: The recv() method overrides the bas
Page 89 and 90: 9.2 ImplementationThe procedures an
Page 91 and 92: Average sending rateTSW window leng
Page 93 and 94: The following command adds an entry
Page 95 and 96: $qCE configQ 0 1 10 20 0.10Note tha
Page 97: Chapter 10AgentsAgents represent en
Page 101 and 102: }bind("windowOption_", &wnd_option_
Page 103 and 104: hdr_flags* nf = (hdr_flags*)npkt->a
Page 105 and 106: public:ECHO_Timer(ECHO_Agent *a) :
Page 107 and 108: 10.6.4 Using the agent through OTcl
Page 109 and 110: State Variables are:dupacks_ Number
Page 111 and 112: $agent attach-tbf Attaches a token
Page 113 and 114: (void)Scheduler::instance().schedul
Page 115 and 116: * outstanding, cancel it.*/void Tcp
Page 117 and 118: Chapter 12Packet Headers and Format
Page 119 and 120: method is now obsolete; its usage i
Page 121 and 122: Packethdrsize_next_bits()points to
Page 123 and 124: the system’s memory allocator. In
Page 125 and 126: }incr hdrlen_ $incrreturn $baseFrom
Page 127 and 128: Chapter 13Error ModelThis chapter d
Page 129 and 130: SimpleLink::errormodule argsSimulat
Page 131 and 132: This is a simple example of how to
Page 133 and 134: Higher LayersNode 1Node 2. . .Node
Page 135 and 136: };void recv(Packet* p, Handler*);vi
Page 137 and 138: and the frame type. It then passes
Page 139 and 140: $ll_ set delay_ $delay$ll_ set band
Page 141 and 142: 14.10 Commands at a glanceThe follo
Page 143 and 144: 15.2.1 Default Hierarchical Setting
Page 145 and 146: Chapter 16Mobile Networking in nsTh
Page 147 and 148: 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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