public function getPerimeters()
    {
        if (null === $this->perimeters) {
            $perimeters = array();
            foreach ($this->perimeterManager->findAll() as $network) {
                $perimeter = new BusinessPerimeter($network->getExternalPerimeterId());
                $perimeter->setId($network->getId());
                $this->perimeters[] = $perimeter;
            }
        }

        return $this->perimeters;
    }