diff --git a/includes/defaults.inc.php b/includes/defaults.inc.php
index 67e1b1d440..25e825248d 100644
--- a/includes/defaults.inc.php
+++ b/includes/defaults.inc.php
@@ -10,7 +10,6 @@ $config['log_file']      = $config['install_dir'] . "/observium.log";
 
 ### Location of executables
 
-$config['sipcalc']        = "/usr/bin/sipcalc";
 $config['rrdtool']        = "/usr/bin/rrdtool";
 $config['fping']          = "/usr/bin/fping";
 $config['snmpwalk']       = "/usr/bin/snmpwalk";
diff --git a/includes/functions.php b/includes/functions.php
index 674067963b..8b03aa44ea 100755
--- a/includes/functions.php
+++ b/includes/functions.php
@@ -551,12 +551,14 @@ function discover_process_ipv6($ifIndex,$ipv6_address,$ipv6_prefixlen,$ipv6_orig
 {
   global $valid_v6,$device,$config;
 
-  $ipv6_network   = trim(shell_exec($config['sipcalc']." $ipv6_address/$ipv6_prefixlen | grep Subnet | cut -f 2 -d '-'"));
-  $ipv6_compressed = trim(shell_exec($config['sipcalc']." $ipv6_address/$ipv6_prefixlen | grep Compressed | cut -f 2 -d '-'"));
+  $ipv6_network = Net_IPv6::getNetmask("$ipv6_address/$ipv6_prefixlen") . '/' . $ipv6_prefixlen;
+  $ipv6_compressed = Net_IPv6::compress($ipv6_address);
 
-  $ipv6_type = trim(shell_exec($config['sipcalc']." $ipv6_address/$ipv6_prefixlen | grep \"Address type\" | cut -f 2- -d '-'"));
-
-  if ($ipv6_type == "Link-Local Unicast Addresses") return; # ignore link-locals (coming from IPV6-MIB)
+  if (Net_IPv6::getAddressType($ipv6_address) == NET_IPV6_LOCAL_LINK)
+  {
+    # ignore link-locals (coming from IPV6-MIB)
+    return;
+  }
 
   if (mysql_result(mysql_query("SELECT count(*) FROM `ports`
         WHERE device_id = '".$device['device_id']."' AND `ifIndex` = '$ifIndex'"), 0) != '0' && $ipv6_prefixlen > '0' && $ipv6_prefixlen < '129' && $ipv6_compressed != '::1')