my ($session, $error) = Net::SNMP->session(
      -community => $results_table->{$group}->{$site_name}->{ro_community},
      -hostname    => $results_table->{$group}->{$site_name}->{mgmt_ip},
      -nonblocking => 0x1,   # Create non-blocking objects
					     );
   if (!defined($session)) {
      printf("ERROR: %s.\n", $error);
      exit 1;
   }