1. Applications and transport agent API 695430050 許庭瑋

2. Outline Application in NS Class Application Attaching applications Class TrafficGenerator Simulated Applications

3. Application in NS On top of transport agents Two basic types  Traffic generators  Simulated applications

4. Application in NS

5. Class Application class Application : public TclObject { public: Application(); virtual void send(int nbytes); virtual void recv(int nbytes); virtual void resume(); protected: int command(int argc, const char*const* argv); virtual void start(); virtual void stop(); Agent *agent_; int enableRecv_; // call OTcl recv or not int enableResume_; // call OTcl resume or not }; *see trafgen.cc/.h

6. Attaching transport agent set src [new Agent/TCP/FullTcp] set sink [new Agent/TCP/FullTcp] $ns_ attach-agent $node_(s1) $src $ns_ attach-agent $node_(k1) $sink $ns_ connect $src $sink

7. Attaching applications Use attach-agent function set ftp1 [new Application/FTP] $ftp1 attach-agent $src  Set agent_  Call attachApp()[agent.cc] An alternative Set ftp1 [$src attach-app FTP]

8. System calls to use transport agent send(int nbytes)  send nbytes of data to peer  if nbytes==-1, infinite send sendmsg(int nbytes, const char* flags = 0)  Identical to send(int bytes)  Additional string flags MSG_EOF

9. System calls to use transport agent close()  Requests the agent to close the connection (only applicable for TCP) listen()  Requests the agent to listen for new connections (only applicable for Full TCP) set_pkttype(int pkttype)  This function sets the type_ variable in the agent to pkttype.

10. Agent upcalls to application In NS, no actual data transfering between applications Agents upcalls application to notify events  Incoming number of bytes of data Two types of upcalls  recv(int nbytes)  resume()

11. Done()  All data has been transferred, and ACKed  Done does nothing by default An example set myagent [new Agent/TCP/FullTcp] $myagent proc done... code you want...

12. Example for FTP set src [new Agent/TCP/FullTcp] set sink [new Agent/TCP/FullTcp] $ns_ attach-agent $node_(s1) $src $ns_ attach-agent $node_(k1) $sink $ns_ connect $src $sink # set up TCP-level connections $sink listen; $src set window_ 100 set ftp1 [new Application/FTP] $ftp1 attach-agent $src $ns_ at 0.0 "$ftp1 start"

13. Class TrafficGenerator class TrafficGenerator : public Application { public: TrafficGenerator(); virtual double next_interval(int &) = 0; virtual void init() {} virtual double interval() { return 0; } virtual int on() { return 0; } virtual void timeout(); virtual void recv() {} virtual void resume() {} protected: virtual void start(); virtual void stop(); double nextPkttime_; int size_; int running_; TrafficTimer timer_; };

14. Class TrafficGenerator Four classes derived from TrafficGenerator  EXPOO_Traffic Exponential on/off duration Fixed rate,packet size  POO_Traffic Pareto on/off distribution  CBR_Traffic  TrafficTrace Generates traffic according to trace file

15. Exponential distribution

16. Exponential On/Off packetSize_  the constant size of the packets generated burst_time_  the average “on” time for the generator idle_time_  the average “off” time for the generator rate_  the sending rate during “on” times Next_packet_time=tr_time+idle _time Example: set e [new Application/Traffic/Expon ential] $e set packetSize_ 210 $e set burst_time_ 500ms $e set idle_time_ 500ms $e set rate_ 100k

17. Pareto Distribution α,β>0 Shape in NS is β

18. Pareto On/Off packetSize_  the constant size of the packets generated burst_time_  the average "on" time for the generator idle_time_  the average "off" time for the generator rate_  the sending rate during "on" times shape_  the "shape" parameter used by the pareto distribution Example: set p [new Application/Traffic/Pareto] $p set packetSize_ 210 $p set burst_time_ 500ms $p set idle_time_ 500ms $p set rate_ 200k $p set shape_ 1.5

19. CBR rate_  the sending rate interval_ (Optional)  interval between packets packetSize_  the constant size of the packets generated random_ flag  indicating whether or not to introduce random “noise” in the scheduled departure times (default isoff) maxpkts_  the maximum number of packets to send (default is (228) Example: set e [new Application/Traffic/CB R] $e set packetSize_ 48 $e set rate_ 64Kb $e set random_ 1

20. Traffic Trace Enable multiple Traffic/Trace associated with one trace file 2 32-bit fields in trace file  Next packet generates time (ms)  Length of next packet (bytes) Example: set tfile [new Tracefile] $tfile filename example- trace set t1 [new Application/Traffic/Trace] $t1 attach-tracefile $tfile set t2 [new Application/Traffic/Trace] $t2 attach-tracefile $tfile

21. Random variable in NS Pareto Distribution Constant Distribution Uniform Distribution Exponential Distribution HyperExponential Distribution

22. Pareto Distribution # Pareto 分佈，柏拉圖分佈 set r1 [new RandomVariable/Pareto] $r1 use-rng $rng $r1 set avg_ 10.0 $r1 set shape_ 1.2 for {set i 1} {$i<=3} {incr i} { puts [$r1 value] }

23. Constant Distribution set r2 [new RandomVariable/Constant] $r2 use-rng $rng $r2 set avg_ 5 for {set i 1} {$i<=3} {incr i} { puts [$r2 value] }

24. Uniform Distribution Set min & max set r3 [new RandomVariable/Uniform] $r3 use-rng $rng $r3 set min_ 0.0 $r3 set max_ 10.0 for {set i 1} {$i<=3} {incr i} { puts [$r3 value] }

25. Exponential Distribution set r4 [new RandomVariable/Exponential] $r4 use-rng $rng $r4 set avg_ 5.0 for {set i 1} {$i<=3} {incr i} { puts [$r4 value] }

26. Example-Exponential traffic set src [new Agent/UDP] set sink [new Agent/UDP] $ns_ attach-agent $node_(s1) $src $ns_ attach-agent $node_(k1) $sink $ns_ connect $src $sink set e [new Application/Traffic/Exponential] $e attach-agent $src $e set packetSize_ 210 $e set burst_time_ 500ms $e set idle_time_ 500ms $e set rate_ 100k $ns_ at 0.0 "$e start"

27. Simulated applications Two simulated applications : FTP & Telnet FTP methods: attach-agent start stop produce n producemore n send n

28. Simulated applications Telnet Packet inter-packet time:  Chose from exponential distribution, with average=interval_ ; (if interval not zero)  Chose according tcplib distribution (see ns- 2.28\tcp\tcplib-telnet.cc)

29. Example CBR + FTP Node 1 CBR Node 2 FTP