1.8 Conclusion

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ARCnet was the first LAN technology to fall by the wayside, with StarLAN to follow soon after. Ethernet and token ring vied for market share throughout the mid-1980s and 1990s before Ethernet pulled ahead. Upon reaching 100 Mbps, it became apparent that token ring would have to either meet that speed or ultimately be abandoned. But by the time token ring reached 100 Mbps, Ethernet advocates had already been looking forward to gigabit speeds. By 2000, Ethernet clearly emerged as the network of choice for most organizations.

Today, Ethernet at the SONET OC-192 rate of 10 Gbps is being deployed by carriers for metropolitan-area networks (MANs) and fat-pipe access to the Internet, while Ethernet at the OC-768 rate of 40 Gbps is in the offing. In Ethernet, service providers are looking for the same things as corporations—a familiar, low-cost, high-speed technology to support networked applications, such as virtual private networks, Internet Protocol (IP) telephony, transparent LAN services and e-commerce. Ethernet running at 10 Gbps offers all that and more. It reduces operational costs because it is the one technology that can be used from LAN to MAN to WAN. Because there is no need for ancillary equipment, such as protocol translators, equipment and operational costs can be greatly reduced.

The seamless connectivity to the installed base of 10-Mbps and 100-Mbps equipment, combined with Ethernet’s scalability and flexibility to handle new applications and data types over a variety of media, makes Gigabit Ethernet a practical choice for high-speed, high-bandwidth networking. The 1000BaseT enables the deployment of Gigabit Ethernet into the large installed base of Category 5 cabling, preserving the investment organizations have made in existing cable infrastructure.

Token ring has held up well for a long time, but under today’s heavy traffic loads, these networks are experiencing congestion problems and must be replaced. For several years, there has been a move within IT organizations to migrate away from obsolete technology, especially since IBM itself has walked away from token ring and has lost interest in high-speed token ring and gigabit token ring. The IEEE has periodically raised the issue of standardizing gigabit token ring, but lack of interest has always discouraged the effort. Even third-party vendors that had specialized in token ring, such as Madge Networks, now sell Ethernet and wireless solutions, while paying lip service to the idea of protecting existing investments in token-ring infrastructure.

Once considered a promising technology, FDDI is also considered a legacy technology and is being replaced with more economical and scaleable alternatives. An extension of FDDI, called FDDI-2, uses portions of its 100-Mbps bandwidth to carry voice and video. FDDI full-duplex technology (FFDT) uses the same network infrastructure but can potentially support data rates up to 200 Mbps. However, neither technology has been widely accepted. Furthermore, FDDI is limited by distance and is expensive to implement. Although FDDI offers high reliability and fault tolerance for mission-critical applications, it has been overtaken by more scaleable technologies such as Gigabit Ethernet, Fibre Channel, and, more recently, Infiniband, which is discussed in Chapter 4 within the context of storage area network (SAN).

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