t is worth consideration only if the objective is to introduce low-speed video communication to the desktop in a limited fashion. Most organizations have abandoned microsegmentation in favor of a new type of arrangement-switching hubs. LAN Switches The easiest and least expensive way to increase throughput for high-traffic desktop video communication is to replace conventional Ethernet hubs with LAN switches. Switching allows the efficient interconnection of multiple LAN segments. Ethernet switches are hybrid internetworking devices that combine circuit switching with packet switching (layer-3 Ethernet switches are, in fact, high-performance routers). Network segments (or devices) are connected to switch ports. Traffic between ports is conveyed across the switch backplane. In this manner, large LANs can be constructed from many smaller LAN segments. In a switched Ethernet environment, users contend for bandwidth only with other users on the same segment. The smaller the segment, the greater the bandwidth available to each station. Because the switching device's backplane speed is faster than individual segments, the aggregate capacity of the LAN is increased. Switching hub ports have an incoming packet cycle and an outgoing packet cycle, each of which operates at 10, 100, 1000, and 10,000 Mbps. If the switch supports LAN segments, it is said to segment switch (most switches do this). Switching hubs can also be arranged to node switch, in which case each desktop is provided with its own Ethernet segment. This is cost-effective only in instances in which a workgroup requires high-speed support, such as full-motion video communication. Video Communications: The Whole Picture Whether a switch is configured to segment switch or node switch, it operates as follows: During an incoming cycle a port opens up to accept a packet. As the packet enters the hub, its MAC layerdestination address is examined and it is briefly buffered until the outgoing hub port associated with the destination address opens to accept traffic. If