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Null Objects Null objects are a subclass of agent objects that implement a traffic sink. They inherit all of the generic agentobject functionality. There are no methods specific to this object. The state variables are:• sport_• dport_LossMonitor Objects LossMonitor objects are a subclass of agent objects that implement a traffic sink which also maintainssome statistics about the received data e.g., number of bytes received, number of packets lost etc. They inherit all ofthe generic agent object functionality.$lossmonitor clearResets the expected sequence number to -1.State Variables are:nlost_ Number of packets lost.npkts_ Number of packets received.bytes_ Number of bytes received.lastPktTime_ Time at which the last packet was received.expected_ The expected sequence number of the next packet.TCP objects TCP objects are a subclass of agent objects that implement the BSD Tahoe TCP transport protocol as describedin paper: "Fall, K., and Floyd, S. Comparisons of Tahoe, Reno, and Sack TCP. December 1995." URL ftp://ftp.ee.lbl.gov/papers/sacks.ps.Z. They inherit all of the generic agent functionality. Configuration Parameters are:window_ The upper bound on the advertised window for the TCP connection.maxcwnd_ The upper bound on the congestion window for the TCP connection. Set to zero to ignore. (This is thedefault.)windowInit_ The initial size of the congestion window on slow-start.windowOption_ The algorithm to use for managing the congestion window.windowThresh_ Gain constant to exponential averaging filter used to compute awnd (see below). For investigationsof different window-increase algorithms.overhead_ The range of a uniform random variable used to delay each output packet. The idea is to insert randomdelays at the source in order to avoid phase effects, when desired [see Floyd, S., and Jacobson, V. On Traffic PhaseEffects in Packet-Switched Gateways. Internetworking: Research and Experience, V.3 N.3, September 1992. pp.115-156 ]. This has only been implemented for the Tahoe ("tcp") version of tcp, not for tcp-reno. This is notintended to be a realistic model of CPU processing overhead.ecn_ Set to true to use explicit congestion notification in addition to packet drops to signal congestion. This allows aFast Retransmit after a quench() due to an ECN (explicit congestion notification) bit.packetSize_ The size in bytes to use for all packets from this source.tcpTick_ The TCP clock granularity for measuring roundtrip times. Note that it is set by default to the non-standardvalue of 100ms.bugFix_ Set to true to remove a bug when multiple fast retransmits are allowed for packets dropped in a single windowof data.maxburst_ Set to zero to ignore. Otherwise, the maximum number of packets that the source can send in response toa single incoming ACK.slow_start_restart_ Set to 1 to slow-start after the connection goes idle. On by default.Defined Constants are:MWS The Maximum Window Size in packets for a TCP connection. MWS determines the size of an array in tcpsink.cc.The default for MWS is 1024 packets. For Tahoe TCP, the "window" parameter, representing the receiver’sadvertised window, should be less than MWS-1. For Reno TCP, the "window" parameter should be lessthan (MWS-1)/2.107
State Variables are:dupacks_ Number of duplicate acks seen since any new data was acknowledged.seqno_ Highest sequence number for data from data source to TCP.t_seqno_ Current transmit sequence number.ack_ Highest acknowledgment seen from receiver. cwnd_ Current value of the congestion window.awnd_ Current value of a low-pass filtered version of the congestion window. For investigations of different windowincreasealgorithms.ssthresh_ Current value of the slow-start threshold.rtt_ Round-trip time estimate.srtt_ Smoothed round-trip time estimate.rttvar_ Round-trip time mean deviation estimate.backoff_ Round-trip time exponential backoff constant.TCP/Reno Objects TCP/Reno objects are a subclass of TCP objects that implement the Reno TCP transport protocol describedin paper: "Fall, K., and Floyd, S. Comparisons of Tahoe, Reno, and Sack TCP. December 1995." URL ftp://ftp.ee.lbl.gov/papers/sacks.ps.Z. There are no methods, configuration parameters or state variables specific to this object.TCP/Newreno Objects TCP/Newreno objects are a subclass of TCP objects that implement a modified version of the BSDReno TCP transport protocol. There are no methods or state variables specific to this object.Configuration Parameters are:newreno_changes_ Set to zero for the default New Reno described in "Fall, K., and Floyd, S. Comparisons of Tahoe,Reno, and Sack TCP. December 1995". Set to 1 for additional New Reno algorithms [see Hoe, J., Improving theStart-up Behavior of a Congestion Control Scheme for TCP. in SIGCOMM 96, August 1996, pp. 270-280. URLhttp://www.acm.org/sigcomm/sigcomm96/papers/hoe.html.]; this includes the estimation of the ssthresh parameterduring slow-start.TCP/Vegas Objects There are no methods or configuration parameters specific to this object. State variables are:• v_alpha_• v_beta_• v_gamma_• v_rtt_TCP/Sack1 Objects TCP/Sack1 objects are a subclass of TCP objects that implement the BSD Reno TCP transport protocolwith Selective Acknowledgement Extensions described in "Fall, K., and Floyd, S. Comparisons of Tahoe, Reno, andSack TCP. December 1995". URL ftp:// ftp.ee.lbl.gov/papers/sacks.ps.Z. They inherit all of the TCP object functionality.There are no methods, configuration parameters or state variables specific to this object.TCP/FACK Objects TCP/Fack objects are a subclass of TCP objects that implement the BSD Reno TCP transport protocolwith Forward Acknowledgement congestion control. They inherit all of the TCP object functionality. There are nomethods or state variables specific to this object.Configuration Parameters are:ss-div4 Overdamping algorithm. Divides ssthresh by 4 (instead of 2) if congestion is detected within 1/2 RTT ofslow-start. (1=Enable, 0=Disable)rampdown Rampdown data smoothing algorithm. Slowly reduces congestion window rather than instantly halving it.(1=Enable, 0=Disable)TCP/FULLTCP Objects This section has not yet been added here. The implementation and the configuration parametersare described in paper: "Fall, K., Floyd, S., and Henderson, T., Ns Simulator Tests for Reno FullTCP. July, 1997." URLftp://ftp.ee.lbl.gov/papers/fulltcp.ps.108
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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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Page 61 and 62: Module NameRtModule/BaseRtModule/Mc
Page 63 and 64: $node neighborsThis returns the lis
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Page 67 and 68: 6.2 ConnectorsConnectors, unlink cl
Page 69 and 70: $ns_ link-lossmodel This function
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Page 73 and 74: }}}void Queue::resume(){Packet* p =
Page 75 and 76: 7.3 Different types of Queue object
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Page 79 and 80: dst_ The destination address of pac
Page 81 and 82: 7.5.2 ConfigurationRunning a JoBS s
Page 83 and 84: mean_pkt_size_ Used to set the expe
Page 85 and 86: Demarker objects$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 and 98: Chapter 10AgentsAgents represent en
Page 99 and 100: CtrMcast/EncapCtrMcast/DecapMessage
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) :
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Page 111 and 112: $agent attach-tbf Attaches a token
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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
Page 149 and 150: 16.1.2 Creating Node movementsThe m
Page 151 and 152: set netif $netif_($t)set mac $mac_(
Page 153 and 154: the hardware address of a packet’
Page 155 and 156: destined to itself to the port dmux
Page 157 and 158: switch(ch->ptype()) {case PT_MAC:br
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16.1.7 Revised format for wireless
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Packet info at "Application level"
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The main problem facing the wired-c
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target_target_encapsulatorreg_agent
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why: This avoids header clashes bet
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This command is used to create a Go
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Chapter 17Satellite Networking in n
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in counter-rotating planes (where t
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• Position/Sat/Geo A geostationar
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$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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