First of all, use strict and -w or warnings.

Now to the problem at hand. You don't give many specifics so the following code just checks to see if the value of $temp[1] changes from line to line in your file:

my $firstLineFlag++;
my $sessid;
while (my $line = <IN>) {
   my @temp = split (/[=]/, $line);
   if ($temp[1] > 100) {
      print "Session id: $temp[1]  ";
   }

   if ($firstLineFlag) {
      $sessid = $temp[1];
      $firstLineFlag = '';
   }
   if ($temp[1] ne $sessid) {
      if ($temp[1] == 20) {
         print " V34\n\n ";
      } elsif ($temp[1] == 9) {
         print " no connection\n\n";
      }
      $sessid = $temp[1];
   }
}
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