set ns [new Simulator] 
 
$ns rtproto DV  
 
set nf [open out1.nam w]
set fh [open log1.txt w] 
$ns trace-all $tr 
$ns namtrace-all $nf 
 
 
proc finish {} { 
      	global ns nf  
      	$ns flush-trace 
	close  $nf 
	exec nam out1.nam & 
	exit 0 
		} 
 
for {set i 0} {$i < 10} {incr i} { 
        set n($i) [$ns node] 
	} 
 
 
for {set j 0} {$j < 10} {incr j} {
  $ns duplex-link $n($j) $n([expr ($j +1)%10]) 1Mb 50ms DropTail 
}

 
set cbr0 [new Agent/CBR] 
$ns attach-agent $n(0) $cbr0 
$cbr0 set packetSize_ 500  
$cbr0 set interval_ 0.01 
 
set null3 [new Agent/Null] 
$ns attach-agent $n(3) $null3 
 
$ns connect $cbr0 $null3 
 
proc mydump2 {node fh} { 
 global ns 
 set now [$ns now] 
 puts "Routing table of node $node at time $now" 
 set dr [$node rtObject?]
 $dr dump-routes $fh
} 

#if you want to see every node routing table you can use this other proc
#(which doesn't write the output on any file)  
#proc mydump {} { 
# global ns 
# set now [$ns now] 
# puts "Routing table at time $now" 
# $ns dump-routelogic-nh 
# $ns dump-routelogic-distance 
#} 
 
$ns at 1.0 "$cbr0 start" 
$ns at 8.0 "$cbr0 stop" 
$ns rtmodel-at 3.0 down $n(0) $n(1) 
$ns rtmodel-at 6.0 up $n(0) $n(1) 
 
$ns at 2.9 "mydump2 $n(2) $fh" 
$ns at 3.31 "mydump2 $n(2) $fh"
$ns at 3.37 "mydump2 $n(2) $fh" 
$ns at 10.0 "finish" 
 
 
$ns run