Extending ns Extending ns In OTcl In C++ Debugging Padma Haldar - PDF document

Outline Extending ns � Extending ns � In OTcl � In C++ � Debugging Padma Haldar USC/ISI 1 2 ns Directory Structure Extending ns in OTcl ns-allinone � If you don’t want to compile � source your changes in your sim Tcl8.3 TK8.3 OTcl tclcl ns-2 nam-1 scripts � Otherwise tcl ... C+ + code � Modifying code; recompile � Adding new files ex test lib mcast ... • Change Makefile (NS_TCL_LIB), examples validation tests tcl/lib/ns-lib.tcl OTcl code • Recompile 3 4 Example: Agent/Message Agent/Message pkt: 64 bytes Receiver-side of arbitrary processing string S R C n2 n4 C cross 128Kb, 50ms traffic n0 n1 � A UDP agent (without UDP header) 10Mb, 1ms 10Mb, 1ms � Up to 64 bytes user message S n3 R n5 � Good for fast prototyping a simple idea msg agent � Usage requires extending ns functionality 5 6 1

Agent/Message: Step 1 Agent/Message: Step 2 � Define sender � Define sender packet processing class Sender class Sender –superclass superclass Agent/Message Agent/Message Sender Sender instproc instproc recv recv msg msg { # Message format: “ # Message format: “Addr Addr Op Op SeqNo SeqNo” $self $self instvar instvar agent_addr agent_addr _ Sender instproc Sender instproc send send-next {} { next {} { set sdr set sdr [lindex lindex $msg msg 0] 0] $self instvar $self instvar seq seq_ _ agent_addr agent_addr_ set seq set seq [lindex lindex $msg msg 2] 2] $self send “$ $self send “$agent_addr agent_addr_ send $ _ send $seq seq_” _” puts "Sender gets puts "Sender gets ack ack $seq seq from $ from $sdr sdr " incr seq incr seq_ } global ns global ns $ns at [ $ns at [expr expr [$ns now]+0.1] "$self send [$ns now]+0.1] "$self send-next" next" } 7 8 Agent/Message: Step 3 Agent/Message: Step 4 � Define receiver packet processing � Scheduler and tracing Class Receiver –superclass Class Receiver superclass Agent/Message Agent/Message # Create scheduler # Create scheduler Receiver Receiver instproc instproc recv recv msg msg { set ns [new Simulator] set ns [new Simulator] $self $self instvar instvar agent_addr agent_addr _ set set sdr sdr [lindex lindex $msg msg 0] 0] # Turn on Tracing # Turn on Tracing set seq set seq [lindex lindex $msg msg 2] 2] set fd set fd [new “ [new “message.tr message.tr” w] ” w] puts “Receiver gets seq puts “Receiver gets seq $seq seq from $ from $sdr sdr ” $ns trace $ns trace-all $ all $ fd fd $self send “$addr $self send “$ addr _ _ ack ack $seq seq” } 9 10 Agent/Message: Step 5 Agent/Message: Step 6 � Topology � Routing for {set i 0} {$i < 6} { for {set i 0} {$i < 6} {incr incr i} { i} { set set n($i n($i) [$ns node] ) [$ns node] # Packet loss produced by # Packet loss produced by queueing queueing } $ns duplex $ns duplex-link $n(0) $n(1) 128kb 50ms link $n(0) $n(1) 128kb 50ms DropTail DropTail $ns duplex $ns duplex-link $n(1) $n(4) 10Mb 1ms link $n(1) $n(4) 10Mb 1ms DropTail DropTail # Routing protocol: let’s run distance # Routing protocol: let’s run distance $ns duplex-link $n(1) $n(5) 10Mb 1ms $ns duplex link $n(1) $n(5) 10Mb 1ms DropTail DropTail vector vector $ns duplex $ns duplex-link $n(0) $n(2) 10Mb 1ms link $n(0) $n(2) 10Mb 1ms DropTail DropTail $ns rtproto $ns rtproto DV DV $ns duplex $ns duplex-link $n(0) $n(3) 10Mb 1ms link $n(0) $n(3) 10Mb 1ms DropTail DropTail $ns queue $ns queue-limit $n(0) $n(1) 5 limit $n(0) $n(1) 5 $ns queue-limit $n(1) $n(0) 5 $ns queue limit $n(1) $n(0) 5 11 12 2

Agent/Message: Step 7 Agent/Message: Step 8 � Cross traffic � Message agents set sdr set sdr [new Sender] [new Sender] set udp0 [new Agent/UDP] set udp0 [new Agent/UDP] $ns attach $ns attach -agent $n(2) $udp0 agent $n(2) $udp0 $sdr sdr set set seq seq_ 0 _ 0 set null0 [new Agent/NULL] set null0 [new Agent/NULL] $sdr sdr set set packetSize packetSize_ 1000 _ 1000 $ns attach -agent $n(4) $null0 $ns attach agent $n(4) $null0 $ns connect $udp0 $null0 $ns connect $udp0 $null0 set rcvr set rcvr [new Receiver] [new Receiver] $rcvr rcvr set set packetSize packetSize_ 40 _ 40 set exp0 [new set exp0 [new Application/Traffic/Exponential] Application/Traffic/Exponential] $ns attach $ns attach-agent $n(3) $ agent $n(3) $sdr sdr $exp0 set rate_ 128k $exp0 set rate_ 128k $ns attach $ns attach-agent $n(5) $ agent $n(5) $rcvr rcvr $exp0 attach -agent $udp0 $exp0 attach agent $udp0 $ns connect $sdr $ns connect $ sdr $rcvr rcvr $ns at 1.0 “$exp0 start” $ns at 1.0 “$exp0 start” $ns at 1.1 “$sdr $ns at 1.1 “$ sdr send send-next” next” 13 14 Agent/Message: Step 9 Agent/Message: Result � End-of-simulation wrapper (as usual) � Example output > ./ns > ./ns msg.tcl msg.tcl Receiver gets Receiver gets seq seq 0 from 3 0 from 3 $ns at 2.0 finish $ns at 2.0 finish Sender gets ack Sender gets ack 0 from 5 0 from 5 proc finish {} { proc finish {} { Receiver gets seq Receiver gets seq 1 from 3 1 from 3 Sender gets ack Sender gets ack 1 from 5 1 from 5 global ns fd global ns fd Receiver gets Receiver gets seq seq 2 from 3 2 from 3 $ns flush-trace $ns flush trace Sender gets ack Sender gets ack 2 from 5 2 from 5 Receiver gets Receiver gets seq seq 3 from 3 3 from 3 close $ close $fd fd Sender gets Sender gets ack ack 3 from 5 3 from 5 exit 0 exit 0 Receiver gets Receiver gets seq seq 4 from 3 4 from 3 } Sender gets ack Sender gets ack 4 from 5 4 from 5 Receiver gets seq Receiver gets seq 5 from 3 5 from 3 $ns run $ns run 15 16 Add Your Changes into ns Add Your Change into ns ns-allinone � tcl/lib/ns-lib.tcl Class Simulator Class Simulator … Tcl8.3 TK8.3 OTcl tclcl ns-2 nam-1 source ../mysrc/msg.tcl source ../ mysrc/msg.tcl � Makefile NS_TCL_LIB = \ NS_TCL_LIB = tcl ... C+ + code tcl/mysrc/msg.tcl tcl/mysrc/msg.tcl \ … mysrc lib mcast ... ex test � Or: change Makefile.in, make distclean , make distclean then ./configure ./configure -- --enable enable-debug , debug , examples validation tests msg.tcl make depend and and make make depend make OTcl code 17 18 3

Outline Extending ns in C++ � Extending ns � Modifying code � In OTcl � make depend � In C++ � Recompile • New components � Adding code in new files � Change Makefile � make depend � recompile 19 20 Creating New Components Guidelines � Guidelines � Decide position in class hierarchy � Two styles � I.e., which class to derive from? � New agent based on existing packet � Create new packet header (if headers necessary) � Add new packet header � Create C++ class, fill in methods � Define OTcl linkage (if any) � Write OTcl code (if any) � Build (and debug) 21 22 New Agent, Old Header TCP Jump Start – Step 1 TclObject Handler � TCP jump start NsObject � Wide-open transmission window at the beginning Connector Classifier � From cwnd _ += 1 To cwnd cwnd_ += 1 cwnd_ = _ = MAXWIN_ MAXWIN_ Queue Delay Agent Trace AddrClassifier McastClasifier DropTail RED TCP Enq Deq Drop Reno SACK JS 23 24 4

TCP Jump Start – Step 2 TCP Jump Start – Step 3 � New file: tcp-js.cc � New file: tcp-js.h static JSTcpClass : public TclClass { public: JSTcpClass () : TclClass("Agent/TCP/JS") class class JSTCPAgent JSTCPAgent : public : public TcpAgent TcpAgent { {} public: public: TclObject* create(int, const char*const*) { virtual void set_initial_window virtual void set_initial_window() { () { return (new JSTcpAgent ()); cwnd cwnd_ = MAXWIN_; _ = MAXWIN_; } } }; JSTcpAgent::JSTcpAgent () { private: private: bind(“MAXWIN _”, MAXWIN_); int int MAXWIN_; MAXWIN_; } }; }; 25 26 Packet Format New Packet Header � Create new header structure ts_ cmn header � Enable tracing support of new header ptype_ header � Create static class for OTcl linkage ip header (packet.h) uid_ data tcp header � Enable new header in OTcl (tcl/lib/ns- size_ packet.tcl) rtp header � This does not apply when you add a iface_ trace header new field into an existing header! ... 27 28 How Packet Header Works Example: Agent/Message Packet � New packet header for 64-byte PacketHeader/ Common next_ message hdrlen_ size determined bits_ � New transport agent to process this hdr_cmn at compile time new header PacketHeader/ I P size determined size determined hdr_ip at compile time at simulator PacketHeader/ TCP startup time ( PacketHeaderManager) size determined hdr_tcp at compile time … … 29 30 5