eeds, Fibre Channel has traditionally been used in the majority of SANs. Switches connected to physical servers use Ethernet-dedicated ports that are adapted for Fibre Channel to communicate with SANs. Thus, the physical servers running applications that need access to data and the storage disks containing the orga- nizations' databases can communicate with one another. Server and Storage Virtualization Accounts receivable applications are examples of applications that access databases. These applications might need to retrieve vendor-addressing information from a Next-Generation Data Centers: Virtualization and Gigabit Speeds centralized database. However, because the SAN in which the database resides is likely running Fibre Channel, a translation device called a gateway is required to translate between the Ethernet switches and the SAN. The following example demonstrates the chain of communications between appli- cations on virtual machines, SANs, and end-user computers. 1. An enterprise employee issues a request over the Ethernet LAN from his computer to view a training video. 2. The request is sent to a video application on a virtual machine in a physical server. 3. The application issues a request for the video, which is in a database in the data center's SAN. 4. The switch connected to the server on which the application resides forwards the request to the disk in the SAN over one of its Fibre Channel-adapted ports. Once it receives the video, the switch sends it via an Ethernet port to the computer that requested it and connects the employee's computer to the video application. In the preceding scenario, data centers support and pay for two sets of interfaces: Ethernet, and Fibre Channel ports on each switch and on each server, plus the associ- ated circuit cards and cables for each interface. This is illustrated in Figure 2-1. Server Switch Switch and server with Fibre Channel (FC) and Ethernet Network Interface Cards (NICs) and ports Figure 2-1 Fibre Channel and Ethernet ports in servers and switches. Da