Dear ns-2 users and experts Hello and good day I am trying to use the Markov-chain idea to create TCP connections passing from a backbone (chain). In my scenario we have a chain like this:
node(0)<---->node(1)<--->node(2)<---->node(3)<---> ...<----> node(n) each node exactly sends several TCP connections (FTP) with random size and random arrival time by an pre-specified order (variable cntcs(backbone) 5 ; in this case 5) However when I start the simulation in gives me "floating point exception". I tried to check all variables and substitute them, but nothing changes, I still get this error. Here is the full Tcl code for your reference (I am using ns-2.29). Thank you in advance for your contribution set ns [new Simulator] set policy [lindex $argv 0] ;# this is the qeueing policy to be applied set tf [open tf.tr w] # Simulation parameters stack set backbone 10 ;# This is the number of Nodes in backbone! (thus number of hops will be backbone-1) set childs 5 ;# This is the number of children nodes each backbone node is connected to! set qsize(backbone) 50 ;#Queue size for backbone nodes set qsize(childs) 50 ;#Queue size for children nodes set bw(backbone) 2Mb ;# link bandwidth for backbone nodes set bw(childs) 2Mb ;#link bandwidth for children nodes set delay(backbone) 10ms ;#link delay for backbone nodes set delay(childs) 10ms ;#link delay for children nodes set cnctn(backbone) 5 ;#Number of connection each backbone node established to each other Backbone node (per backbone node)! set lambda(backbone) 10; # lambda for each backbone node set mu(backbone) 20000 ;# mu? (average file size in bytes for backbone transfers) set shape(backbone) 1.5 ;# Pareto file size shape of backbone tranfers $ns trace-all $tf proc finish {} { global ns tf $ns flush-trace close $tf exit 0 } # backbone node declaration for {set i 0} {$i<$backbone} {incr i} { set n($i) [$ns node] ;# "n" series of nodes are in backbone only! } # children nodes declaration for {set i 0} {$i<$backbone} {incr i} { for {set j 0} {$j<$childs} {incr j} { set c($i,$j) [$ns node] ;# "c" series of nodes are children nodes only! } } #create wired links for backbone for {set i 0} {$i<$backbone-1} {incr i} { set k [expr $i+1] $ns duplex-link $n($i) $n($k) $bw(backbone) $delay(backbone) $policy $ns queue-limit $n($i) $n($k) $qsize(backbone) $ns queue-limit $n($k) $n($i) $qsize(backbone) } #create wired links for children nodes for {set i 0} {$i<$backbone} {incr i} { for {set j 0} {$j<$childs} {incr j} { $ns duplex-link $n($i) $c($i,$j) $bw(childs) $delay(childs) $policy $ns queue-limit $n($i) $c($i,$j) $qsize(childs) $ns queue-limit $c($i,$j) $n($i) $qsize(childs) } } #creating backbone/backbone TCP source and destinations for {set i 0} {$i<$backbone} {incr i} { for {set j 0} {$j<$backbone} {incr j} { for {set k 0} {$k<$cnctn(backbone)} {incr k} { set tcp_back($i,$j,$k) [new Agent/TCP/Newreno] $ns attach-agent $n($i) $tcp_back($i,$j,$k) set sink_back($i,$j,$k) [new Agent/TCPSink/DelAck] $ns attach-agent $n($j) $sink_back($i,$j,$k) $ns connect $tcp_back($i,$j,$k) $sink_back($i,$j,$k) set ftp_back($i,$j,$k) [$tcp_back($i,$j,$k) attach-source FTP] # $tcp_back($i,$j,$k) set fid_ 1 } } } # Generators for random file size and inter-arrival times set rng1(back) [new RNG] $rng1(back) seed 1 set rng2(back) [new RNG] $rng2(back) seed 1 #Random inter-arrival times at each source set RV(back) [new RandomVariable/Exponential] $RV(back) set avg_ [expr 1/$lambda(backbone)] $RV(back) use-rng $rng1(back) #Random file sizes set RVsize(back) [new RandomVariable/Pareto] $RVsize(back) set avg_ $mu(backbone) $RVsize(back) set shape_ $shape(backbone) $RVsize(back) use-rng $rng2(back) # Starting the connections (start time and size usage) for {set i 0} {$i<$backbone} {incr i} { for {set j 0} {$j<$backbone} {incr j} { set t [$ns now] for {set k 0} {$k<$cnctn(backbone)} {incr k} { set t [expr $t+[$RV(back) value]] set Conct($i,$j,$k) $t set Size($j,$j,$k) [expr [$RVsize(back) value]] $ns at $Conct($i,$j,$k) "$ftp_back($i,$j,$k) send 10000" } } } $ns at 10 "finish" $ns run -- Naeem Khademi --------------------------------------------------------- Student of Master of Computer Science University Putra Malaysia ---------------------------------------------------------