FDDI technology wins, but wanes

FDDI technology wins, but wanes

George Kotelly

Executive Editor


Although Fiber Distributed Data Interface (fddi) technology is confronted by newer and faster high-speed network backbone technologies, it continues to maintain its role as a leading transport standard. Relatively unpublicized over the past several years, this 100-Mbit/sec data network technology has served diligently and reliably since the mid-1980s. Effectively balancing cost, speed and scalability, this technology has achieved a large installed base in corporate local area networks (LANs) because of its straightforward management and fault-tolerance capabilities.

Indeed, it provides an orderly ring network in which computers intercommunicate via data transfers. Because fddi is deliberately structured as a backbone network and incorporates management and fault- tolerance capabilities, it lets many low-speed clients access a few high-speed servers and also interconnects the servers--PCs or supercomputers.

To determine fddi`s competitive merits, InfoWorld recently compared it to two relatively new backbone networking types--100Base-T Fast Ethernet and 155-Mbit/sec Asynchronous Transfer Mode (ATM). The publication implemented a test network setup and a series of performance tests using commercially available equipment. Based on six network measurement categories--installation, two speed benchmarks, manageability, troubleshooting and cost--it concluded that fddi narrowly outperformed Fast Ethernet but widely outclassed ATM. The test network represented a typical business installation and common distance, performance and management parameters. The network comprised five servers, one backbone switch, two edge switches and more than 50 computers.

The three technologies transport data differently through the network and possess their own special attributes. However, when all six measurement categories were totaled, fddi prevailed, mostly because of its strong error-recovery characteristics.

According to the publication`s testers, network administrators would have no problems installing an fddi network, which ranked second to Fast Ethernet in this category. The network edge switching devices and servers were easily configured. A key factor is that fddi`s ring topology eliminates the need to run all the network connections to a central location.

In two speed test categories, the fddi network tied the other two competitors in one test benchmark and finished second to ATM in the other.

Fddi trailed ATM in manageability, according to the testers. However, in an fddi ring network, every device is intelligent. Consequently, users can remove faulty devices without assistance from the network administrator. Moreover, fddi equipment supports the full range of simple network management protocol standards and performs comprehensively as a managed backbone network.

The most-compelling performance factor, however, proved to be fddi`s troubleshooting and error-recovery capabilities, where it outdistanced Fast Ethernet and ATM. Via its dual-ring topology, fddi presents a high level of fault tolerance and enables quick identification of network problems. According to the testers, these capabilities were unmatched by standard installations of the other two technologies.

Because the fddi test network needed only two network edge switches and five network interface cards, but no backbone switch, it cost slightly more than $23,000, placing it second, behind Fast Ethernet.

Despite its strong performance as the backbone network technology of choice against Fast Ethernet and ATM, the dominance of fddi technology appears to be temporary. Apparently, fddi manufacturers are improving network performance with fddi-II, but users are demanding much faster speeds. As a result, Gigabit Ethernet is on the horizon, and gigabit wavelength-division multiplexing technology is already being used. These technologies are grabbing the press headlines and users` attention.

According to Jerry Hobbs, analyst at Kessler Marketing Intelligence Corp., a Newport, RI-based fiber optics market- research company, "Although the relative market share of fddi ports continued to decrease from 18% of all optical data ports installed in the United States in 1995, the overall volume of fddi ports will continue to increase through 1997. Afterward, the annual volume of fddi port installations will gradually decline, yet remain above 600,000 ports installed through the year 2000. The decline of annual fddi port volume in U.S. markets can be attributed to the acceptance of ATM and switched Ethernet transmission protocols."

Unless fddi technology meets current and future backbone network marketing and performance challenges, it will fall victim to the relentless pursuit of faster and more-energetic network technologies. q

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