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the destination node id of outgoing packet. Other nodes listen in the preamble and record the time slots to receive packets.Like other common TDMA protocols (GSM, for example), each node has a data transmission slot to send packets.To avoid unnecessary power consumption, each node turns its radio on and off explicitly by invoking node API set_node_sleep().The radio only needs to be on when: in the pramble phase (takes one slot time) and there is a packet to send and receive.The preamble is implemented as a central data structure tdma_preamble_, which is accessible to all the nodes. At thebeginning of a frame, each node writes the destination node id into its subslot in preamble if it has a packet to send. Followingpreamble phase, each node sends packet in its data transmission slot and checks the preamble to determine if there is a packetto receive in other slots.The following parameters are user configurable: the wireless link bandwidth bandwith_, the slot length packet_slot_len_,and the number of nodes max_node_num_. See ~ns/mac-tdma.{cc,h} for implementation details.16.1.5 Different types of Routing Agents in mobile networkingThe four different ad-hoc routing protocols currently implemented for mobile networking in nsare dsdv, dsr, aodv and tora.In this section we shall briefly discuss each of them.DSDVIn this routing protocol routing messages are exchanged between neighbouring mobilenodes (i.e mobilenodes that are withinrange of one another). Routing updates may be triggered or routine. Updates are triggered in case a routing information fromone of t he neighbours forces a change in the routing table. A packet for which the route to its destination is not known iscached while routing queries are sent out. The pkts are cached until route-replies are received from the destination. There isa maximum buffer size for caching the pkts waiting for routing information beyond which pkts are dropped.All packets destined for the mobilenode are routed directly by the address dmux to its port dmux. The port dmux handsthe packets to the respective destination agents. A port number of 255 is used to attach routing agent in mobilenodes. Themobilenodes al so use a default-target in their classifier (or address demux). In the event a target is not found for the destinationin the classifier (which happens when the destination of the packet is not the mobilenode itself), the pkts are handed to thedefault-ta rget which is the routing agent. The routing agent assigns the next hop for the packet and sends it down to the linklayer.The routing protocol is mainly implemented in C++. See ~ns/dsdv directory and ~ns/tcl/mobility/dsdv.tcl for all proceduresrelated to DSDV protocol implementation.DSRThis section briefly describes the functionality of the dynamic source routing protocol. As mentioned earlier the SRNode isdifferent from the MobileNode. The SRNode’s entry_ points to the DSR routing agent, thus forcing all packets receivedby the node to be handed down to the routing agent. This model is required for future implementation of piggy-backed routinginformation on data packets which otherwise would not flow through the routing agent.The DSR agent checks every data packet for source-route information. It forwards the packet as per the routing information.Incase it doesnot find routing information in the packet, it provides the source route, if route is known, or caches the packetand sends out route queries if route to destination is not known. Routing queries, always triggered by a data packet with noroute to its destination, are initially broadcast to all neighbours. Route-replies are send back either by intermediate nodes orthe destination node, to the source, if it can find routing info for the destination in the route-query. It hands over all packets153
destined to itself to the port dmux. In SRNode the port number 255 points to a null agent since the packet has already beenprocessed by the routing agent.See ~ns/dsr directory and ~ns/tcl/mobility/dsr.tcl for implementation of DSR protocol.TORATora is a distributed routing protocol based on "link reversal" algorithm. At every node a separate copy of TORA is run forevery destination. When a node needs a route to a given destination it broadcasts a QUERY message containing the addressof the destination for which it requires a route. This packet travels through the network until it reaches the destination oran intermediate node that has a route to the destination node. This recepient node node then broadcasts an UPDATE packetlisting its height wrt the destination. As this node propagates through the network each node updates its height to a valuegreater than the height of the neighbour from which it receives the UPDATE. This results in a series of directed links from thenode that originated the QUERY to the destination node. If a node discovers a particular destination to be unreachable it setsa local maximum value of height for that destination. Incase the node cannot find any neighbour having finite height wrt thisdestination it attempts to find a new route. In case of network partition, the node broadcasts a CLEAR message that resets allrouting states and removes invalid routes from the network.TORA operates on top of IMEP (Internet MANET Encapsulation Protocol) that provides reliable delivery of route-messagesand informs the routing protocol of any changes of the links to its neighbours. IMEP tries to aggregate IMEP and TORAmessages into a single packet (called block) in order to reduce overhead. For link-status sensing and maintaining a list ofneighbour nodes, IMEP sends out periodic BEACON messages which is answered by each node that hears it by a HELLOreply message. See ns/tora directory and ns/tcl/mobility/tora.tcl for implementation of tora in ns.AODVAODV is a combination of both DSR and DSDV protocols. It has the basic route-discovery and route-maintenance of DSRand uses the hop-by-hop routing, sequence numbers and beacons of DSDV. The node that wants to know a route to a givendestination generates a ROUTE REQUEST. The route request is forwarded by intermediate nodes that also creates a reverseroute for itself from the destination. When the request reaches a node with route to destination it generates a ROUTE REPLYcontaining the number of hops requires to reach destination. All nodes that participates in forwarding this reply to the sourcenode creates a forward route to destination. This state created from each node from source to destination is a hop-by-hop stateand not the entire route as is done in source routing. See ns/aodv and ns/tcl/lib/ns-lib.tcl for implementational details of aodv.16.1.6 Trace SupportThe trace support for wireless simulations currently use cmu-trace objects. In the future this shall be extended to merge withtrace and monitoring support available in ns, which would also include nam support for wireless modules. For now we willexplain briefly with cmu-trace objects and how they may be used to trace packets for wireless scenarios.The cmu-trace objects are of three types - CMUTrace/Drop, CMUTrace/Recv and CMUTrace/Send. These are used fortracing packets that are dropped, received and sent by agents, routers, mac layers or interface queues in ns. The methods andprocedures used for implementing wireless trace support can be found under ~ns/trace.{cc,h} and ~ns/tcl/lib/ns-cmutrace.tcl.A cmu-trace object may be created by the following API:set sndT [cmu-trace Send "RTR" $self]154
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18 Radio Propagation Models 17718.1
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30 Multicast Routing 25130.1 Multic
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38.2.5 An example . . . . . . . . .
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X Other 40347 Educational use of NS
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# so, we lied. now, we define the t
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Chapter 2Undocumented FacilitiesNs
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Part IInterface to the Interpreter1
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• if you can do what you want by
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• tcl.result(const char* s)Pass t
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By convention in ns, the class Agen
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$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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Page 111 and 112: $agent attach-tbf Attaches a token
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Page 133 and 134: Higher LayersNode 1Node 2. . .Node
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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
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Page 147 and 148: entry_addrdemuxIP addressdefaulttar
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Page 175 and 176: • Position/Sat/Geo A geostationar
Page 177 and 178: $ns add-isl $ltype $node1 $node2 $b
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Page 187 and 188: $satnode add-isl This method c
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the persistent queue length in the
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Thruput2 0.054024 60000residue_pos_
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Chapter 22DelayBox: Per-Flow Delay
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$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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