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26.4 Trace File FormatThe Trace::format() method defines the trace file format used in trace files produced by the Trace class. It is constructedto maintain backward compatibility with output files in earlier versions of the simulator (i.e., ns v1) so that ns v1post-processing scripts continue to operate. The important pieces of its implementation are as follows:// this function should retain some backward-compatibility, so that// scripts don’t break.void Trace::format(int tt, int s, int d, Packet* p){hdr_cmn *th = (hdr_cmn*)p->access(off_cmn_);hdr_ip *iph = (hdr_ip*)p->access(off_ip_);hdr_tcp *tcph = (hdr_tcp*)p->access(off_tcp_);hdr_rtp *rh = (hdr_rtp*)p->access(off_rtp_);packet_t t = th->ptype();const char* name = packet_info.name(t);if (name == 0)abort();int seqno;/* XXX *//* CBR’s now have seqno’s too */if (t == PT_RTP || t == PT_CBR)seqno = rh->seqno();else if (t == PT_TCP || t == PT_ACK)seqno = tcph->seqno();elseseqno = -1;...if (!show_tcphdr_) {sprintf(wrk_, "%c %g %d %d %s %d %s %d %d.%d %d.%d %d %d",tt,Scheduler::instance().clock(),s,d,name,th->size(),flags,iph->flowid() /* was p->class_ */,iph->src() >> 8, iph->src() & 0xff, // XXXiph->dst() >> 8, iph->dst() & 0xff,seqno,th->uid() /* was p->uid_ */);// XXX} else {sprintf(wrk_,"%c %g %d %d %s %d %s %d %d.%d %d.%d %d %d %d 0x%x %d",tt,Scheduler::instance().clock(),s,d,235
}name,th->size(),flags,iph->flowid() /* was p->class_ */,iph->src() >> 8, iph->src() & 0xff,iph->dst() >> 8, iph->dst() & 0xff,seqno,th->uid(), /* was p->uid_ */tcph->ackno(),tcph->flags(),tcph->hlen());// XXX// XXXThis function is somewhat unelegant, primarily due to the desire to maintain backward compatibility. It formats the source,destination, and type fields defined in the trace object (not in the packet headers), the current time, along with various packetheader fields including, type of packet (as a name), size, flags (symbolically), flow identifier, source and destination packetheader fields, sequence number (if present), and unique identifier. The show_tcphdr_ variable indicates whether thetrace output should append tcp header information (ack number, flags, header length) at the end of each output line. Thisis especially useful for simulations using FullTCP agents (Section 34.3). An example of a trace file (without the tcp headerfields) might appear as follows:+ 1.84375 0 2 cbr 210 ------- 0 0.0 3.1 225 610- 1.84375 0 2 cbr 210 ------- 0 0.0 3.1 225 610r 1.84471 2 1 cbr 210 ------- 1 3.0 1.0 195 600r 1.84566 2 0 ack 40 ------- 2 3.2 0.1 82 602+ 1.84566 0 2 tcp 1000 ------- 2 0.1 3.2 102 611- 1.84566 0 2 tcp 1000 ------- 2 0.1 3.2 102 611r 1.84609 0 2 cbr 210 ------- 0 0.0 3.1 225 610+ 1.84609 2 3 cbr 210 ------- 0 0.0 3.1 225 610d 1.84609 2 3 cbr 210 ------- 0 0.0 3.1 225 610- 1.8461 2 3 cbr 210 ------- 0 0.0 3.1 192 511r 1.84612 3 2 cbr 210 ------- 1 3.0 1.0 196 603+ 1.84612 2 1 cbr 210 ------- 1 3.0 1.0 196 603- 1.84612 2 1 cbr 210 ------- 1 3.0 1.0 196 603+ 1.84625 3 2 cbr 210 ------- 1 3.0 1.0 199 612Here we see 14 trace entries, five enque operations (indicated by “+” in the first column), four deque operations (indicated by“-”), four receive events (indicated by “r”), and one drop event. (this had better be a trace fragment, or some packets wouldhave just vanished!). The simulated time (in seconds) at which each event occurred is listed in the second column. The nexttwo fields indicate between which two nodes tracing is happening. The next field is a descriptive name for the the type ofpacket seen (Section 26.5). The next field is the packet’s size, as encoded in its IP header.The next field contains the flags, which not used in this example. The flags are defined in the flags[] array in trace.cc. Fourof the flags are used for ECN: “E” for Congestion Experienced (CE) and “N” for ECN-Capable-Transport (ECT) indicationsin the IP header, and “C” for ECN-Echo and “A” for Congestion Window Reduced (CWR) in the TCP header. For the otherflags, “P” is for priority, and “F” is for TCP Fast Start.The next field gives the IP flow identifier field as defined for IP version 6. 1 . The subsequent two fields indicate the packet’ssource and destination node addresses, respectively. The following field indicates the sequence number. 2 The last field is a1 In ns v1, each packet included a class field, which was used by CBQ to classify packets. It then found additional use to differentiate between “flows”at one trace point. In ns v2, the flow ID field is available for this purpose, but any additional information (which was commonly overloaded into the classfield in ns v1) should be placed in its own separate field, possibly in some other header2 In ns v1, all packets contained a sequence number, whereas in ns v2 only those Agents interested in providing sequencing will generate sequencenumbers. Thus, this field may not be useful in ns v2 for packets generated by agents that have not filled in a sequence number. It is used here to remainbackward compatible with ns v1.236
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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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Page 215 and 216: Part IIISupport214
Page 217 and 218: endenddocument pargvcPrint out argc
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Page 257 and 258: — The procedure init-all{} is a g
Page 259 and 260: Global Actions Once the detailed ac
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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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