if(dbFetchCell('SELECT COUNT(*) from ipv4_mac WHERE port_id = ? AND ipv4_address = ? AND `context_name`= ?',array($interface['port_id'],$ip,$device['context_name']))){
// Commented below, no longer needed but leaving for reference.
// $sql = "UPDATE `ipv4_mac` SET `mac_address` = '$clean_mac' WHERE port_id = '".$interface['port_id']."' AND ipv4_address = '$ip'";
$old_mac=dbFetchCell('SELECT mac_address from ipv4_mac WHERE ipv4_address=? AND port_id=? AND `context_name`= ?',array($ip,$interface['port_id']),$device['context_name']);
dbUpdate(array('mac_address'=>$clean_mac),'ipv4_mac','port_id=? AND ipv4_address=? AND `context_name`= ?',array($interface['port_id'],$ip,$device['context_name']));
$sql="SELECT * from ipv4_mac AS M, ports as I WHERE M.port_id = I.port_id and I.device_id = ' AND `context_name`= ?".$device['device_id']." AND M.context_name='".$device['context_name']."'";
foreach(dbFetchRows($sql)as$entry){
$entry_mac=$entry['mac_address'];
$entry_if=$entry['port_id'];
if(!$mac_table[$entry_if][$entry_mac]){
dbDelete('ipv4_mac','`port_id` = ? AND `mac_address` = ? AND `context_name`= ?',array($entry_if,$entry_mac,$device['context_name']));
d_echo("Removing MAC $entry_mac from interface ".$interface['ifName']);