public function walkIPv4($oid) {
        if ($this->cache() && ( $rtn = $this->getCache()->load($oid) ) !== null) {
            return $rtn;
        }

        $this->_lastResult = $this->realWalk($oid);

        if ($this->_lastResult === false) {
            throw new Exception('Could not perform walk for OID ' . $oid);
        }

        $result = array();

        foreach ($this->_lastResult as $_oid => $value) {
            $oids = explode('.', $_oid);

            $len = count($oids);

            $result[$oids[$len - 4] . '.' . $oids[$len - 3] . '.' . $oids[$len - 2] . '.' . $oids[$len - 1]] = $this->parseSnmpValue($value);
        }

        return $this->getCache()->save($oid, $result);
    }