ALTHOUGH many organizations don't need a full 100 megabits per second (Mbps) bandwidth for their LANs, plenty of them clearly need more bandwidth than 10Mbps Ethernet or 16Mbps Token Ring networks provide. Employing a LAN switch device can provide immediate relief and play an important role in migration to 100Mbps LANs (e.g., 100BaseT Ethernet, 100VG-AnyLAN, Fiber Distributed Data Interface (FDDI), and Asynchronous Transfer Mode (ATM)). Overnight migration to 100Mbps LANs is difficult, mostly due to the adapter and cabling changes required by these higher-speed LANs.
For wide-area links, Frame Relay is the current darling of the networking industry. It makes the interconnection of multiple LANs relatively easy, and its use for audio-video data streams further enhances its popularity. In contrast, ATM should be viewed as a lower-level building block for constructing large, complex, high-speed LANs. For example, ATM technology is often used inside Frame Relay networks.
Also, be aware all these high-speed LAN and WAN connections are continually being revisited and revised. For example, FDDI II has been defined to support isochronous traffic over FDDI networks. Similarly, both ATM and Frame Relay continue to be improved and refined. So as you evaluate these technologies, take a hard look at both the features they offer today and those coming in the near future.