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$a0 network $netobj$a0 set fid_ 26$a0 set prio_ 2$ns connect $a0 $a1Note that the configuration of the flow ID and priority are handled through the Agent base class. The purpose of settingthe flow id field in the common header is to label packets belonging to particular flows of live data. Such packets can bedifferentially treated with respect to drops, reorderings, etc. The connect method instructs agent $a0 to send its live trafficto the $a1 agent via the current route through the simulated topology.44.4 Network ObjectsNetwork objects provide access to a live network. There are several forms of network objects, depending on the protocollayer specified for access to the underlying network, in addition to the facilities provided by the host operating system. Useof some network objects requires special access privileges where noted. Generally, network objects provide an entrypointinto the live network at a particular protocol layer (e.g. link, raw IP, UDP, etc) and with a particular access mode (read-only,write-only, or read-write). Some network objects provide specialized facilities such as filtering or promiscuous access (i.e.the pcap/bpf network object) or group membership (i.e. UDP/IP multicast). The C++ class Network is provided as a baseclass from which specific network objects are derived. Three network objects are currently supported: pcap/bpf, raw IP, andUDP/IP. Each are described below.44.4.1 Pcap/BPF Network ObjectsThese objects provide an extended interface to the LBNL packet capture library (libpcap). (See ftp://ftp.ee.lbl.gov/libpcap.tafor more info). This library provides the ability to capture link-layer frames in a promiscuous fashion from network interfacedrivers (i.e. a copy is made for those programs making use of libpcap). It also provides the ability to read and write packettrace files in the “tcpdump” format. The extended interface provided by ns also allows for writing frames out to the networkinterface driver, provided the driver itself allows this action. Use of the library to capture or create live traffic may be protected;one generally requires at least read access to the system’s packet filter facility which may need to be arranged througha system administrator.The packet capture library works on several UNIX-based platforms. It is optimized for use with the Berkeley Packet Filter(BPF) [25], and provides a filter compiler for the BPF pseudomachine machine code. On most systems supporting it, a kernelresidentBPF implementation processes the filter code, and applies the resulting pattern matching instructions to receivedframes. Those frames matching the patterns are received through the BPF machinery; those not matching the pattern areotherwise unaffected. BPF also supports sending link-layer frames. This is generally not suggested, as an entire properlyformattedframe must be created prior to handing it off to BPF. This may be problematic with respect to assigning properlink-layer headers for next-hop destinations. It is generally preferable to use the raw IP network object for sending IP packets,as the system’s routing function will be used to determine proper link-layer encapsulating headers.Configuration Pcap network objects may be configured as either associated with a live network or with a trace file. Ifassociated with a live network, the particular network interface to be used may be specified, as well as an optional promiscuousflag. As with all network objects, they may be opened for reading or writing. Here is an example:set me [exec hostname]set pf1 [new Network/Pcap/Live]$pf1 set promisc_ true385
set intf [$pf1 open readonly]puts "pf1 configured on interface $intf"set filt "(ip src host foobar) and (not ether broadcast)"set nbytes [$pf1 filter $filt]puts "filter compiled to $nbytes bytes"puts "drops: [$pf1 pdrops], pkts: [$pf1 pkts]"This example first determines the name of the local system which will be used in constructing a BPF/libpcap filter predicate.The new Network/Pcap/Live call creates an instance of the pcap network object for capturing live traffic. Thepromisc_ flag tells the packet filter whether it should configure the undelying interface in promiscuous mode (if it is supported).The open call activates the packet filter, and may be specified as readonly, writeonly, or readwrite. Itreturns the name of the network interface the filter is associated with. The open call takes an optional extra parameter (notillustrated) indicating the name of the interface to use in cases where a particular interface should be used on a multi-homedhost. The filter method is used to create a BPF-compatible packet filter program which is loaded into the underlying BPFmachinery. The filter method returns the number of bytes used by the filter predicate. The pdrops and pkts methodsare available for statistics collection. They report the number of packets dropped by the filter due to buffer exhaustion and thetotal number of packets that arrived at the filter, respectively (not the number of packets accepted by the filter).44.4.2 IP Network ObjectsThese objects provide raw access to the IP protocol, and allow the complete specification of IP packets (including header).The implementation makes use of a raw socket. In most UNIX systems, access to such sockets requires super-user privileges.In addition, the interface to raw sockets is somewhat less standard than other types of sockets. The class Network/IPprovides raw IP functionality plus a base class from which other network objects implementing higher-layer protocols arederived.Configuration The configuration of a raw IP network object is comparatively simple. The object is not associated withany particular physical network interface; the system’s IP routing capability will be used to emit the specified datagram outwhichever interface is required to reach the destination address contained in the header. Here is an example of configuring anIP object:set ipnet [new Network/IP]$ipnet open writeonly...$ipnet closeThe IP network object supports only the open and close methods.44.4.3 IP/UDP Network ObjectsThese objects provide access to the system’s UDP implementation along with support for IP multicast group membershipoperations. IN PROGRESS386
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18 Radio Propagation Models 17718.1
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30 Multicast Routing 25130.1 Multic
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38.2.5 An example . . . . . . . . .
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X Other 40347 Educational use of NS
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# so, we lied. now, we define the t
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Chapter 2Undocumented FacilitiesNs
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Part IInterface to the Interpreter1
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• if you can do what you want by
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• tcl.result(const char* s)Pass t
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By convention in ns, the class Agen
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$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"$ns run35.5.2 Mu
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Chapter 36Agent/SRMThis chapter des
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36.1.2 Other Configuration Paramete
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3.6274 n 0 m r 1 type repair servi
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3.6029 n 3 m r 2 Q NTIMER at 3.730
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36.4 Loss Detection—The Class SRM
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same packet. The repair objet does
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}hdr_asrm* seh = (hdr_asrm*) p->acc
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set grp [Node allocaddr]$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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Page 341 and 342: Application FTP FTP objects produce
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Page 345 and 346: 39.1.4 Transmitting user data over
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Page 359 and 360: Object Type Event Type Explaination
Page 361 and 362: Chapter 40Worm ModelIn this chapter
Page 363 and 364: $w local-p 0.5Following are some co
Page 365 and 366: (nsnode) clientcloudPackM ime(nsnod
Page 367 and 368: HTTP responsesclients servers Delay
Page 369 and 370: 41.5 Commands at a GlanceThe follow
Page 371 and 372: • HTTP response size (bytes)• s
Page 373 and 374: Chapter 42Session-level Packet Dist
Page 375 and 376: 42.1.2 Inserting a Loss ModuleWhen
Page 377 and 378: Delay and Loss Modules Each receive
Page 379 and 380: Chapter 43Asim: approximate analyti
Page 381 and 382: set n(1) [$ns node]set link(0:1) [$
Page 383 and 384: Part VIIIEmulation382
Page 385: When using the emulation mode, a sp
Page 389 and 390: puts "install nets into taps..."$a0
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
Page 397 and 398: dst_portaddr,seqno,flags,sname);A n
Page 399 and 400: • up• down• right• left•
Page 401 and 402: 46.1.7 Agent TracingAgent trace eve
Page 403 and 404: v -t 1.0 -e node_tclscript 2 "Echo
Page 405 and 406: If nam ever gets to the end of an e
Page 407 and 408: l :link-t time-s source id-d des
Page 409 and 410: E :D :P :a :session enqueue-t time
Page 411 and 412: v :V :N :W :g :A :c :q :execute tcl
Page 413 and 414: $ns duplex-link-op orient right$ns
Page 415 and 416: Chapter 47Educational use of NS and
Page 417 and 418: Bibliography[1] C. Alaettinoğlu, A
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