puts "\nEnter the number of networks you need to simulate: "
gets stdin num_lo

puts "\n\nGenerating loopback adresses..\n"
for {set x 0} {$x < $num_lo} {incr x} {
   ios_config "interface loop $x" "ip address 10.2.[expr $x * 5].1 255.255.255.0"
}

set result [exec {show ip int brief}]
puts $result