es in the past, hub bandwidth may be divided to serve many segments with only a few ports. A single hub might be capable of supporting as many as 30 different LAN segments. Individual hubs are connected via backbones that conform to one of two designs: collapsed or distributed. In a collapsed backbone, hubs connect to multi-port bridges (no intelligence), switches (intelligence generally at layer 2), or routers (intelligence at layer 3). Each subnet (sub-network) served by the departmental hub is, typically, bridged to an Ethernet network that connects all devices to a campus or building hub (or series of hubs) and, from there, to other sites and to WAN services. The packet switching technique that conventional routers use does not scale well. As Packet-switched Networks traffic increases, the router's bus becomes saturated (the term 'router' is largely synonymous with the term 'layer-3 switch'). Consequently, its switching logic (a router must read an entire packet before it can switch that packet to its destination) may fall behind and cause long delays. These delays devastate video applications. The distributed backbone approach employs a faster backbone network to interconnect campus or building hubs. Hub-based LANs are bridged or routed to the fast backbone. In contrast to the collapsed backbone method of relying on one large router, distributed backbones rely on a number of moderately sized routers. If segmentation is used as a method to increase speed, the network design becomes a collapsed backbone configuration. Microsegmentation has consequences. Bridge ports and router ports are expensive. Moreover, microsegmentation is hard to administer. When clients and servers are not isolated on the same subnet, they must traverse LAN boundaries. This often causes backbone networks to slow to unacceptable levels. Another drawback of traditional shared-media hubs is that everything connected to a particular hub competes for a slice of the hub's backplane bandwidth. Microsegmentation offers a short-term solution tha