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ns-2

ns-2. Polly Huang USC/ISI huang@isi.edu. Modeling The Internet. Web. Web. TCP. TCP. www.cs.columbia.edu. Internet. Network. Network. Link/Physical. Link/Physical. ns-2. Network Simulator Version 2 (ns-2) Help to debug problems in a controlled environment

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ns-2

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  1. ns-2 Polly Huang USC/ISI huang@isi.edu

  2. Modeling The Internet Web Web TCP TCP www.cs.columbia.edu Internet Network Network Link/Physical Link/Physical

  3. ns-2 • Network Simulator Version 2 (ns-2) • Help to debug problems in a controlled environment • Performance Analysis of hypothetical changes

  4. C++ and otcl Separation • C++ for data • per packet action • otcl for control • periodic or triggered action • Compromize between composibility and speed • Learning & debugging

  5. Hello World - Interactive Mode swallow 71% ns % set ns [new Simulator] _o3 % $ns at 1 “puts \“Hello World!\”” 1 % $ns at 1.5 “exit” 2 % $ns run Hello World! swallow 72%

  6. Hello World - Passive Mode simple.tcl set ns [new Simulator] $ns at 1 “puts \“Hello World!\”” $ns at 1.5 “exit” $ns run swallow 74% ns simple.tcl Hello World! swallow 75%

  7. Basic tcl proc test {} { set a 43 set b 27 set c [expr $a + $b] set d [expr [expr $a - $b] * $c] for {set k 0} {$k < 10} {incr k} { if {$k < 5} { puts “k < 5, pow= [expr pow($d, $k)]” } else { puts “k >= 5, mod= [expr $d % $k]” } } } test

  8. Class mom mom instproc greet {} { $selfinstvar age_ puts “$age_ years old mom: How are you doing?” } Class kid -superclass mom kid instproc greet {} { $selfinstvar age_ puts “$age_ years old kid: What’s up, dude?” } set a [new mom] $a set age_ 45 set b [new kid] $b set age_ 15 $a greet $b greet Basic otcl

  9. Basic ns-2 • Creating network • Computing routes • Creating connection • Creating traffic • Inserting errors • Monitoring

  10. Creating Network • Nodes • set ns [new Simulator] • set n0 [$ns node] • set n1 [$ns node] • Links & Queuing • $ns duplex-link $n0 $n1 <bandwidth> <delay> <queue_type> • <queue_type>: DropTail, RED, CBQ, WFQ, SFQ, DRR

  11. Creating Network: LAN • LAN • $ns make-lan <node_list> <bandwidth> <delay> <ll_type> <ifq_type> <mac_type> <channel_type> • <ll_type>: LL • <ifq_type>: Queue/DropTail, • <mac_type>: MAC/802_3 • <channel_type>: Channel

  12. Computing routes • Unicast • $ns rtproto <type> • <type>: Static, Session, DV, cost, multi-path • Multicast • Simulator set EnableMcast_ 1 • Simulator set NumberInterfaces_ 1 • $ns mrtproto <type> • <type>: CtrMcast, DM, dynamicDM, pimDM

  13. Creating Connection: UDP • UDP • set udp [new Agent/UDP] • set null [new Agent/NULL] • $ns attach-agent $n0 $udp • $ns attach-agent $n1 $null • $ns connect $udp $null

  14. Creating Connection: TCP • TCP • set tcp [new Agent/TCP] • set tcpsink [new Agent/TCPSink] • $ns attach-agent $n0 $tcp • $ns attach-agent $n1 $tcpsink • $ns connect $tcp $tcpsink

  15. Creating Traffic • FTP • set ftp [new Application/FTP] • $ftp attach-agent $tcp • Telnet • set telnet [new Application/Telnet] • Web • set session [new httpSession $ns <numPages> <clientNode>]

  16. Creating Traffic: On Top of TCP • FTP • set ftp [new Application/FTP] • $ftp attach-agent $tcp • $ns at <time> “$ftp start” • Telnet • set telnet [new Application/Telnet] • $telnet attach-agent $tcp

  17. Creating Traffic: Trace Driven • Trace driven • set tfile [new Tracefile] • $tfile filename <file> • set src [new Application/Traffic/Trace] • $src attach-tracefile $tfile • <file>: • Binary format • inter-packet time (msec) and packet size (byte)

  18. Summary: Generic Script Structure set ns [new Simulator] # [Turn on tracing] # Create topology # Setup packet loss, link dynamics # Create routing agents # Create: # - multicast groups # - protocol agents # - application and/or setup traffic sources # Post-processing procs # Start simulation

  19. n0 n1 Example Script set ns [new Simulator] set n0 [$ns node] set n1 [$ns node] set ftp [new Application/FTP] $ftp attach-agent $tcp $ns at 0.2 "$ftp start" $ns at 1.2 ”exit" $ns run $ns duplex-link $n0 $n1 1.5Mb 10ms DropTail set tcp [$ns create-connection TCP $n0 TCPSink $n1 0]

  20. Inserting Errors • Creating Error Module • set loss_module [new ErrorModel] • $loss_module set rate_ 0.01 • $loss_module unit pkt • $loss_module ranvar [new RandomVariable/Uniform] • $loss_module drop-target [new Agent/Null] • Inserting Error Module • $ns lossmodel $loss_module $n0 $n1

  21. Tracing • Trace packets on all links • $ns trace-all [open test.out w] <event> <time> <from> <to> <pkt> <size>--<flowid> <src> <dst> <seqno> <aseqno> + 1 0 2 cbr 210 ------- 0 0.0 3.1 0 0 - 1 0 2 cbr 210 ------- 0 0.0 3.1 0 0 r 1.00234 0 2 cbr 210 ------- 0 0.0 3.1 0 0 • Trace packets on all links in nam-1 format • $ns namtrace-all [open test.nam w]

  22. Visualization Tools • nam-1 (Network AniMator Version 1) • xgraph

  23. Network Dynamics • Link failures • Hooks in routing module to reflect routing changes • Four models $ns rtmodel Trace <config_file> $n0 $n1 $ns rtmodel Exponential {<params>} $n0 $n1 $ns rtmodel Deterministic {<params>} $n0 $n1 $ns rtmodel-at <time> up|down $n0 $n1 • Parameter list [<start>] <up_interval> <down_interval> [<finish>]

  24. Other ns-2 Freatures • Mathematical Support • Multi-access Media (some link layer support) • Network Dynamics • Simulation Scale • 460 nodes, 100,000 TCP connections • Emulation Interface

  25. Discrete Event Scheduler time_, uid_, next_, handler_ head_ -> head_ -> handler_ -> handle() insert time_, uid_, next_, handler_

  26. n0 n1 Port Classifier Multicast Node dmux_ Addr Classifier classifier_ Node entry Node entry dmux_ entry_ entry_ Multicast Classifier classifier_ multiclassifier_ Network Topology - Node Unicast Node

  27. n0 n1 n1 entry_ head_ enqT_ queue_ deqT_ link_ ttl_ drophead_ drpT_ Network Topology - Link

  28. n0 n1 Port Classifier Addr Classifier n1 entry_ Node entry 0 head_ dmux_ enqT_ queue_ deqT_ link_ ttl_ 1 entry_ classifier_ drophead_ drpT_ Routing

  29. n0 n1 Port Classifier Port Classifier Addr Classifier Addr Classifier 0 1 dmux_ dmux_ 1 0 entry_ entry_ classifier_ classifier_ Link n1-n0 Routing (cont.) Link n0-n1

  30. dst_=0.0 dst_=1.0 Agent/TCPSink Agent/TCP agents_ 1 0 1 0 Transport n0 n1 Port Classifier Port Classifier Addr Classifier Addr Classifier 0 0 agents_ dmux_ dmux_ Link n0-n1 entry_ entry_ classifier_ classifier_ Link n1-n0

  31. Application/FTP dst_=0.0 dst_=1.0 0 1 1 0 Application n0 n1 Port Classifier Port Classifier Addr Classifier Addr Classifier Agent/TCPSink Agent/TCP 0 0 agents_ agents_ dmux_ dmux_ Link n0-n1 entry_ entry_ classifier_ classifier_ Link n1-n0

  32. dst_=0.0 dst_=1.0 0 1 1 0 Packet Flow n0 n1 Port Classifier Application/FTP Port Classifier Addr Classifier Addr Classifier Agent/TCPSink Agent/TCP 0 0 Link n0-n1 entry_ entry_ Link n1-n0

  33. ts_ cmn header ptype_ ip header uid_ tcp header size_ rtp header iface_ trace header ... Packet Format header data

  34. sim tcl8.0 tk8.0 otcl Tcl ns-2 nam-1 ... tcl ex test lib ... ns-2 Directory Structure tcl code C++ code example validation test tcl code core

  35. Topology Generation • http://www.isi.edu/nsnam/ns/ns-topogen.html

  36. Scenario Generation • http://www-mach.cs.berkeley.edu/ns/ns-scengeneration.html • agent-gen-script.tcl • Source generator files • source topo-gen.tcl • source agent-gen.tcl • source route-gen.tcl

  37. topo-gen.tcl • GT-ITM • topology • outfile <file> • type <graph_type> : random or transit_stub • nodes <num_nodes> • connection_prob <probability>

  38. route-gen.tcl • Routing • outfile <file> • unicast <ucast_type> • multicast <mcast_type>

  39. agent-gen.tcl • Agents • outfile <file> • transport <transport_type> • src <application_type> • sink <transport_sink_type> • num <num_connections or %> • start <start_time> • stop <stop_time>

  40. Wireless Support: Setup • set ns [new Simulator] • set chan [new Channel/WirelessChannel] • set prop [new Propagation/TwoRayGround] • set topo [new Topography] • $topo load_flatgrid <length> <width> • $prop topology $topo

  41. Wireless Support: MobileNode • Creating mobile nodes • set mnode [<routing>-create-mobile-node <node_id>] • <routing>: dsdv or dsr • Node coordinates • $mnode set X_ <x> • $mnode set Y_ <y> • $mnode set Z_ 0

  42. Mobility Support: Movement • Specified • $ns at 1.0 “$mnode setdest <x> <y> <speed>” • Random • $ns at 1.0 “$mnode start”

  43. time 1.2s G2 time 1.3s time 1.35s G2 G1 G2 Example: Multicast Routing • Dynamic group membership under Dense Mode n2 1.5Mb, 10ms 1.5Mb, 10ms time 1.25s n0 n1 G1 1.5Mb, 10ms G2 n3

  44. Multicast: Step 1 • Scheduler, tracing, and topology # Create scheduler set ns [new Simulator] # Turn on multicast $ns multicast # Turn on Tracing set fd [new “mcast.nam” w] $ns namtrace-all $fd

  45. Multicast: Step 2 • Topology # Create nodes set n0 [$ns node] set n1 [$ns node] set n2 [$ns node] set n3 [$ns node] # Create links $ns duplex-link $n0 $n1 1.5Mb 10ms DropTail $ns duplex-link $n0 $n2 1.5Mb 10ms DropTail $ns duplex-link $n0 $n3 1.5Mb 10ms DropTail

  46. Multicast: Step 3 • Routing and group setup # Routing protocol: let’s run distance vector $ns mrtproto DM # Allocate group addresses set group1 [Node allocaddr] set group2 [Node allocaddr]

  47. Multicast: Step 4 • Sender 0 # Transport agent for the traffic source set udp0 [new Agent/UDP] $ns attach-agent $n1 $udp0 $udp0 set dst_addr_ $group1 $udp0 set dst_port_ 0 # Constant Bit Rate source #0 set cbr0 [new Application/Traffic/CBR] $cbr0 attach-agent $udp0 # Start at time 1.0 second $ns at 1.0 "$cbr0 start"

  48. Multicast: Step 5 • Sender 1 # Transport agent for the traffic source set udp1 [new Agent/UDP] $ns attach-agent $n3 $udp1 $udp1 set dst_addr_ $group2 $udp1 set dst_port_ 0 # Constant Bit Rate source #0 set cbr1 [new Application/Traffic/CBR] $cbr1 attach-agent $udp1 # Start at time 1.1 second $ns at 1.1 "$cbr1 start"

  49. Multicast: Step 6 • Receiver with dynamic membership # Can also be Agent/Null set rcvr [new Agent/LossMonitor] # Assign it to node $n2 $ns at 1.2 "$n2 join-group $rcvr $group2" $ns at 1.25 "$n2 leave-group $rcvr $group2" $ns at 1.3 "$n2 join-group $rcvr $group2" $ns at 1.35 "$n2 join-group $rcvr $group1"

  50. Multicast: Step 7 • End-of-simulation wrapper (as usual) $ns at 2.0 "finish" proc finish {} { global ns fd close $fd $ns flush-trace puts "running nam..." exec nam out.nam & exit 0 } $ns run

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