 the packet is destined for a node on the same segment as the sending device, it does not cross the switch's backplane. If the packet is addressed to a node on a different segment, it must move across the high-speed backplane and through the silicon-based switching fabric. In this way, Ethernet switching hubs support multiple simultaneous 10/100/1000 Mbps connections between nodes, segments and combinations thereof. In switching, only the sending and destination port are aware of the packet's existence. Hence, the network is not overwhelmed with extraneous packets. In effect, a switch changes Ethernet from a contention broadcast system to a direct delivery system. In a node-switched arrangement, it creates the illusion that each station has its own private subnet that allows it to send and receive data at Ethernet's full 10 Mbps (for a total throughput of 20 Mbps). This same bandwidth can be sub-divided among a small group of stations in a segment switched arrangement. Thus, isochronous service is delivered to a user or group of users whose real-time applications drive the need for a LAN environment from destructive collisions. Switches are available for 10, 100, and 1000 Mbps Ethernet. Numerous manufacturers offer products in each category. The 100 Mbps switches are most effective when positioned as traffic control points for the backbone. In this environment, a hub is attached to every port on the Ethernet switch. 100 Mbps Ethernet switches can also extend the diameter of a 100 Mbps Ethernet LAN beyond its 250-meter limit. The per-port price of the 1000 Mbps Ethernet switch limits deployment to high-end applications. Switched 100 or 1000 Mbps Ethernet would most often apply to video applications in situations where multimedia servers store MPEG-2 encoded material that must traverse the LAN. In a few cases, 1000 Mbps is being extended directly to the desktop but, to obtain maximum value from this approach, supported nodes should be equipped with fast (PCI class or higher) buses. The Ethernet switch is best suite