public function lastChanges($asUnixTimestamp = false) {
        $lc = $this->getSNMP()->walk1d(self::OID_IF_LAST_CHANGE);

        if ($asUnixTimestamp) {
            $sysUptime = $this->getSNMP()->useSystem()->uptime() / 100;

            foreach ($lc as $i => $t) {
                if ($t) {
                    $lc[$i] = intval(floor(time() - $sysUptime + ( $t / 100 )));
                }
            }
        }

        return $lc;
    }