The Cisco MDS 9000 Series Multilayer SAN Switches can help lower the total cost of ownership ofthe most demanding storage environments. By combining a robust and flexible hardwarearchitecture with multiple layers of network and storage-management intelligence， the Cisco MDS 9000 Series helps you build highly available， scalable storage networks with advanced securityand unified management. What method does the Cisco MDS 9000 Series use to support trunking？（）