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if { $MacTrace == "ON" } {## Trace RTS/CTS/ACK Packets#set rcvT [cmu-trace Recv "MAC" $self]$mac log-target $rcvT## Trace Sent Packets#set sndT [cmu-trace Send "MAC" $self]$sndT target [$mac sendtarget]$mac sendtarget $sndT## Trace Received Packets#set rcvT [cmu-trace Recv "MAC" $self]$rcvT target [$mac recvtarget]$mac recvtarget $rcvT## Trace Dropped Packets#set drpT [cmu-trace Drop "MAC" $self]$mac drop-target $drpT} else {$mac log-target [$ns_ set nullAgent_]$mac drop-target [$ns_ set nullAgent_]}# ============================================================}$self addif $netifThe plumbing in the above method creates the network stack we see in Figure 16.1.Each component is briefly described here. Hopefully more detailed docuentation from CMU shall be available in the future.Link Layer The LL used by mobilenode is same as described in Chapter 14. The only difference being the link layer formobilenode, has an ARP module connected to it which resolves all IP to hardware (Mac) address conversions. Normallyfor all outgoing (into the channel) packets, the packets are handed down to the LL by the Routing Agent. The LL handsdown packets to the interface queue. For all incoming packets (out of the channel), the mac layer hands up packets tothe LL which is then handed off at the node_entry_ point. The class LL is implemented in ~ns/ll.{cc,h} and~ns/tcl/lan/ns-ll.tcl.ARP The Address Resolution Protocol (implemented in BSD style) module receives queries from Link layer. If ARP hasthe hardware address for destination, it writes it into the mac header of the packet. Otherwise it broadcasts an ARPquery, and caches the packet temporarily. For each unknown destination hardware address, there is a buffer for a singlepacket. Incase additional packets to the same destination is sent to ARP, the earlier buffered packet is dropped. Once151
the hardware address of a packet’s next hop is known, the packet is inserted into the interface queue. The classARPTable is implemented in ~ns/arp.{cc,h} and ~ns/tcl/lib/ns-mobilenode.tcl.Interface Queue The class PriQueue is implemented as a priority queue which gives priority to routing rotocol packets,inserting them at the head of the queue. It supports running a filter over all packets in the queue and removes those witha specified destination address. See ~ns/priqueue.{cc,h} for interface queue implementation.Mac Layer The IEEE 802.11 distributed coordination function (DCF) Mac protocol has been implemented by CMU. It usesa RTS/CTS/DATA/ACK pattern for all unicast packets and simply sends out DATA for all broadcast packets. Theimplementation uses both physical and virtual carrier sense. The class Mac802_11 is implemented in ~ns/mac-802_11.{cc,h}.Tap Agents Agents that subclass themselves as class Tap defined in mac.h can register themselves with the mac objectusing method installTap(). If the particular Mac protocol permits it, the tap will promiscuously be given all packetsreceived by the mac layer, before address filtering is done. See ~ns/mac.{cc,h} for class Tapmplementation.Network Interfaces The Network Interphase layer serves as a hardware interface which is used by mobilenode to access thechannel. The wireless shared media interface is implemented as class Phy/WirelessPhy. This interface subjectto collisions and the radio propagation model receives packets transmitted by other node interfaces to the channel. Theinterface stamps each transmitted packet with the meta-data related to the transmitting interface like the transmissionpower, wavelength etc. This meta-data in pkt header is used by the propagation model in receiving network interfaceto determine if the packet has minimum power to be received and/or captured and/or detected (carrier sense) by thereceiving node. The model approximates the DSSS radio interface (Lucent WaveLan direct-sequence spread-spectrum).See ~ns/phy.{cc.h} and ~ns/wireless-phy.{cc,h} for network interface implementations.Radio Propagation Model It uses Friss-space attenuation (1/r 2 ) at near distances and an approximation to Two ray Ground(1/r 4 ) at far distances. The approximation assumes specular reflection off a flat ground plane. See ~ns/tworayground.{cc,h}for implementation.Antenna An omni-directional antenna having unity gain is used by mobilenodes. See ~ns/antenna.{cc,h} for implementationdetails.16.1.4 Different MAC layer protocols for mobile networkingIn ns, two MAC layer protocols are implemented for mobile networks, which are 802.11 and TDMA. In this section we brieflydiscuss each of them.802.11 MAC protocolSee ~ns/mac-802_11.{cc,h} for implementation details.Preamble based TDMA protocolNote: this works is still at a preliminary stage, some practical issues, such as: contention in the preamble phase and time slotreuse in a multi-hop environment are not considered.Unlike contention based MAC protocol (802.11, for example), a TDMA MAC protocol allocates different time slots for nodesto send and receive packets. The superset of these time slots is called a TDMA frame.Currently, ns supports a single hop, preamble-based TDMA MAC protocol. With this protocl, a TDMA frame containspreamble besides the data transmission slots. Within the preamble, every node has a dedicated subslot and uses it to broadcast152
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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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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
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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: set netif $netif_($t)set mac $mac_(
Page 155 and 156: destined to itself to the port dmux
Page 157 and 158: switch(ch->ptype()) {case PT_MAC:br
Page 159 and 160: 16.1.7 Revised format for wireless
Page 161 and 162: Packet info at "Application level"
Page 163 and 164: The main problem facing the wired-c
Page 165 and 166: target_target_encapsulatorreg_agent
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Page 169 and 170: This command is used to create a Go
Page 171 and 172: Chapter 17Satellite Networking in n
Page 173 and 174: in counter-rotating planes (where t
Page 175 and 176: • Position/Sat/Geo A geostationar
Page 177 and 178: $ns add-isl $ltype $node1 $node2 $b
Page 179 and 180: $satrouteobject_ compute_routeswher
Page 181 and 182: This will add an error model to the
Page 183 and 184: lh_firstnameobj‘‘name’’ is
Page 185 and 186: from routing agentto Node->entrySat
Page 187 and 188: $satnode add-isl This method c
Page 189 and 190: set prop [new Propagation/FreeSpace
Page 191 and 192: 18.3.2 Using shadowing modelBefore
Page 193 and 194: Chapter 19Energy Model in nsEnergy
Page 195 and 196: Chapter 20Directed DiffusionThe dir
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21.2 Implementation of XCP in NSIn
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the persistent queue length in the
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Thruput2 0.054024 60000residue_pos_
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Chapter 22DelayBox: Per-Flow Delay
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$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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