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21.4 Test-suites for XCPThe xcp test-suite uses 3 tests. The first one is similar to the one we discussed in the earlier section. It consists of a dumb-belltopology where 3 xcp flows share a bottleneck link. The second test has a similar topology having 3 xcp and 1 tcp flow sharingthe same bottleneck. And finally the last test is built on Dina Katabi’s parking-lot experiment referred in her SIGCOMM’02paper. It is a downsized version of Dina’s example. The test uses a 9-hop link string topology. It has 10 long XCP flows thatflow through the entire length of the chain topology. Then it has 10 XCP flows that run through each hop, starting at (n-1)thhop and ending at nth hop and so on creating the intermittent flows. And finally there are long XCP flows in the reversedirection, starting from the last (10th) node and ending in the first (1st) node. There is a bottleneck at the middle of the chaintopology. Thus the third test employs a large and complex topology and shows the utilization, queue length and packet dropvalues at every link.21.5 Commands at a glanceFollowing is a list of commands used for xcp related simulation in ns.set xcp_src [new Agent/TCP/Reno/XCP]This command creates an XCP source agent.set xcp_dst [new Agent/TCPSink/XCPSink]This command creates an XCP sink.$ns duplex-link $R0 $R1 Mb ms XCPThis code creates a duplex link with specified bandwidth and link delay using an XCP router between node R0 and R1.$xcp_queue set-link-capacity This command propagates the link bandwidth information to the xcp queue which uses it for the router feedback calculation.set tfile [open tfile w]$xcp_queue attach $tfileThis Tcl command allows a file to be attached for tracing xcp queue parameters.$xcp_src attach-trace $xcp_src tracevar This command allows the xcp sources to trace variables.$queue queue-sample-everyrtt $rtt_valueThis command allows the user to set rtt interval values at which variables like packet_drops and queue lengths are measuredat the xcp queue.Queue/XCP set tcp_xcp_on_ 1This flag lets tcp and xcp flows to use the same xcp router. This flag is a temporary fix and should go away when dynamicqueue weights come into effect.207
Chapter 22DelayBox: Per-Flow Delay and LossDelayBox is an ns node that should be placed in between the source and destination nodes. With Delaybox, packets froma TCP flow can be delayed, dropped, and/or forced through a bottleneck link before being passed on to the next node. Adistribution can be used to specify delay, loss, and/or bottleneck link speed for a source - destination pair. Each flow betweenthat source - destination pair draws from the distribution to determine its characteristics. Delays in DelayBox are per-flow,rather than per-packet. Since DelayBox distinguishes between flows, the fid_ variable (flow identifier) should be set foreach flow in the simulation. DelayBox can be used with both Tcp and FullTcp agents.22.1 Implementation DetailsDelayBox maintains two tables: a rule table and a flow table. Entries in the rule table are added by the user in the OTclsimulation script and give an outline of how flows from a source to a destination should be treated. The fields are source,destination, delay Random Variable (in ms), loss rate Random Variable (in fraction of packets dropped), and bottleneck linkspeed Random Variable (in Mbps). The bottleneck link speed field is optional. Entries in the flow table are created internallyand specify exactly how each flow should be handled. Its values are obtained by sampling from the distributions given in therule table. The fields are source, destination, flow ID, delay, loss, and bottleneck link speed (if applicable). Full-TCP flowsare defined as beginning at the receipt of the first SYN of a new flow ID and ending after the sending of the first FIN. Packetsafter the first FIN are forwarded immediately (i.e., they are neither delayed nor dropped by DelayBox). For TcpAgent,flows are defined as beginning at the receipt of the first 40 byte packet of a new flow ID. Since there are no FIN packets inTcpAgent, TcpAgent flows are never considered finished nor are they removed from the flow table.DelayBox also maintains a set of queues to handle delaying packets. There is one queue per entry in the flow table. Thesequeues are implemented as delta queues, in that the time to transfer the packet is kept only for the head packet. All otherpackets are stored with the difference between the time they should be transferred and the time the previous packet shouldbe transferred. The actual time the previous packet should be transferred is stored in the variable deltasum_, named sobecause it is the sum of all delta values in the queue (including the head packet’s transfer time). If the bottleneck link speedhas been specified for the flow, a processing delay is computed for each packet by dividing the size of the packet by the flow’sbottleneck link speed.When a packet is received, its transfer time (current time + delay) is calculated. (This transfer time is the time that the first bitof the packet will begin transfer. Packets that wait in the queue behind this packet must be delayed by the amount of time totransfer all bits of the packet over the bottleneck link.) There are two scenarios to consider in deciding how to set the packet’sdelta:208
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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 $mac_(
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the hardware address of a packet’
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destined to itself to the port dmux
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Page 215 and 216: Part IIISupport214
Page 217 and 218: endenddocument pargvcPrint out argc
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Page 221 and 222: Chapter 25Mathematical SupportThe s
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Global Actions Once the detailed ac
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This dumps next hop information in
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$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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