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41.1.2 PackMimeHTTP Server ApplicationEach web server controls the response sizes that are transferred. The server is started by when a new TCP connection isstarted. Each PackMimeHTTP client takes the following steps:• listen for an HTTP request from the associated client• when the entire request arrives, the server samples the server delay time from the server delay distribution• set a timer to expire when the server delay has passed• when the timer expires, the server sends response (the size of which was sampled by the client and passed to the server)• this process is repeated until the requests are exhausted – the server is told how many requests will be sent in theconnection• send a FIN to close the connection41.2 PackMimeHTTP Random VariablesThis implementation of PackMimeHTTP provides several ns RandomVariable objects for specifying distributions of Pack-MimeHTTP connection variables. The implementations were taken from source code provided by Bell Labs and modified tofit into the ns RandomVariable framework. This allows PackMimeHTTP connection variables to be specified by any type ofns RandomVariable, which now include PackMimeHTTP-specific random variables. If no RandomVariables are specified inthe TCL script, PackMimeHTTP will set these automatically.The PackMimeHTTP-specific random variable syntax for TCL scripts is as follows:• $ns [new RandomVariable/PackMimeHTTPFlowArrive ], where rate is the specified Pack-MimeHTTP connection rate (number of new connections per second)• $ns [new RandomVariable/PackMimeHTTPReqSize ], where rate is the specified PackMime-HTTP connection rate• $ns [new RandomVariable/PackMimeHTTPRspSize ], where rate is the specified PackMime-HTTP connection rate• $ns [new RandomVariable/PackMimeHTTPPersistRspSize]• $ns [new RandomVariable/PackMimeHTTPPersistent ], where probability isthe probability that the connection is persistent• $ns [new RandomVariable/PackMimeHTTPNumPages ], whereprobability is the probability that there is a single page in the connection and shape and scale are parametersto the Weibull distribution to determine the number of pages in the connection.• $ns [new RandomVariable/PackMimeHTTPSingleObjPages ], where probabilityis the probability that there is a single object on the current page.• $ns [new RandomVariable/PackMimeHTTPObjsPerPage ], where shape and scaleare parameters to the Gamma distribution to determine the number of objects on a single page.• $ns [new RandomVariable/PackMimeHTTPTimeBtwnObjs]• $ns [new RandomVariable/PackMimeHTTPTimeBtwnPages]365
HTTP responsesclients servers DelayBox DelayBox webFigureweb41.2: Example Topology Using PackMimeHTTP and DelayBox. The cloud of web clients is a single ns node, and thecloud of web servers is a single ns node. Each of the DelayBox nodes is a single ns node.requests HTTP• $ns [new RandomVariable/PackMimeHTTPServerDelay ], where shape and scaleare paramters to the Weibull distribution to determine server delay.• $ns [RandomVariable/PackMimeHTTPXmit ], where type is 0 for client-side delaysand 1 for server-side delays. Note: This random variable is only used in conjunction with DelayBox. It returns 1/2 ofthe actual delay because it is meant to be used with 2 DelayBox nodes, each of which should delay the packets for 1/2of the actual delay.41.3 Use of DelayBox with PackMime-HTTPPackMimeHTTP uses ns to model the TCP-level interaction between web clients and servers on the simulated link. Tosimulate network-level effects of HTTP transfer through the clouds, use DelayBox (see 22). DelayBox is an ns analog todummynet, often used in network testbeds to delay and drop packets. The delay times model the propagation and queuingdelay incurred from the source to the edge of the cloud (or edge of the cloud to destination). Since all HTTP connections inPackMimeHTTP take place between only two ns nodes, there must be an ns object to delay packets in each flow, rather thanjust having a static delay on the link between the two nodes. DelayBox also models bottleneck links and packet loss on anindividual connection basis. Two DelayBox nodes are used as shown in Figure 41.3. One node is placed in front of the webclient cloud ns node to handle client-side delays, loss, and bottleneck links. The other DelayBox node is placed in front ofthe web server cloud ns node to handle the server-side delays, loss, and bottleneck links.41.4 ExampleMore examples (including those that demonstrate the use of DelayBox with PackMime) are available in the tcl/ex/packmime/directory of the ns source code. The validation script test-suite-packmime.tcl is in tcl/test/ and can be runwith the command test-all-packmime from that directory.Note: The only PackMime-HTTP parameters that must be set are rate, client, server, flow_arrive, req_size,and rsp_size. The example below shows the minimal parameters that need to be set, but other parameters can be set tochange the default behavior (see “Commands at a Glance”).# test-packmime.tcl# useful constantsset CLIENT 0set SERVER 1366
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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 $mac_(
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the hardware address of a packet’
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destined to itself to the port dmux
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switch(ch->ptype()) {case PT_MAC:br
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16.1.7 Revised format for wireless
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Packet info at "Application level"
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The main problem facing the wired-c
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target_target_encapsulatorreg_agent
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why: This avoids header clashes bet
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This command is used to create a Go
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Chapter 17Satellite Networking in n
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in counter-rotating planes (where t
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• Position/Sat/Geo A geostationar
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$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"$ns run35.5.2 Mu
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Chapter 36Agent/SRMThis chapter des
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36.1.2 Other Configuration Paramete
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3.6274 n 0 m r 1 type repair servi
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Page 383 and 384: Part VIIIEmulation382
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Page 387 and 388: set intf [$pf1 open readonly]puts "
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Page 391 and 392: Chapter 45Nam45.1 IntroductionNam i
Page 393 and 394: • Button 6 (Chevron logo) - Close
Page 395 and 396: Second, when dealing with randomly
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Page 399 and 400: • up• down• right• left•
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Bibliography[1] C. Alaettinoğlu, A
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