ATM shortcomings spawn competition

ATM shortcomings spawn competition

George Kotelly

Executive Editor

According to trade press reports, industry interviews and observations made at this spring`s Networld+Interop trade show, Asynchronous Transfer Mode (ATM) technology appears to have bogged down in implementation and application. Because of this slowdown in user acceptance, existing and new communications technologies, such as faster-running Ethernet variations, local area network (LAN) switching, Cells in Frames and Internet protocols, have stepped to the forefront to meet user demands for improved network speed, security, management and interoperability.

A high-speed, multimedia-handling, switching technology that uses fixed 53-byte cells in place of variable frame lengths to switch voice, video and data communications, ATM can now deliver 155-megabit-per-second transmissions and scale to 622-Mbit/sec and higher transmissions over long-distance (kilometer) fiber-optic and short-distance (meter) copper-wire networks.

Unfortunately, existing or legacy LAN equipment has been unable to handle the increased traffic pouring out of ATM switches, and, therefore, network bottlenecks have disrupted services. More important, though, ATM does not work well with the proven and standard Internet Protocol (IP) unless complex software modifications are made.

Other common user complaints against ATM technology include usage complexity, high cost, deficient multivendor interoperability and numerous standards changes, and modifications and approvals by the 700-plus members of the ruling ATM Forum. According to both users and analysts, ATM protocols have proven so difficult to understand and apply that numerous ATM network deployments have been put on hold.

In this era of rapid network expansion and competition, alternative technology solutions have quickly appeared. Indeed, network planners and providers are evaluating accelerated Ethernet switching, routing and bridging technologies. With more than 20 years of experience, Ethernet is a proven technology in price, performance, compatibility and application.

Another approach, which was introduced at the Networld+Interop show, comes from Ipsilon Networks Inc. in Palo Alto, CA. This company has developed an IP networking product that apparently overcomes the weaknesses of ATM. In fact, this product won the Networld+Interop Best-of-Show Product Award--no small feat, considering that Ipsilon is a new company and presented its product in a small exhibitor booth tucked away in a show section called "Start-up City."

The Ipsilon product integrates IP routing software with high-speed ATM switching hardware in a single scalable platform. Using an intelligent classification, but proprietary, scheme, the product dynamically shifts between store-and-forward routing and cut-through switching based on traffic needs. The company claims its product supports throughputs to 5.3 million IP packets per second, nearly twice that heralded for equivalent-sized ATM switches, provides interoperability with other IP switches in an IP-type network, and costs half the price of conventional devices. More important, though, the product maintains full compatibility with existing IP networks, applications and network-management tools.

"Users--not standards bodies--drive networking standards," states Tom Lyon, Ipsilon founder and chief technical officer. Comments Fred McClimans, industry analyst at Decisys Inc. in Sterling, VA, "The Ipsilon technology allows [vendors] to expand their hardware platforms with minimal effort from ATM-only to value-added ATM-plus-IP switching functionality."

Other networking competitors involve evolutionary LAN technologies. According to analysts, these technologies are meeting the advantages of ATM quality-of-service functions head on, including higher speeds, dedicated bandwidth, isochronous support, improved management, and multicast and bandwidth reservation.

John McQuillan, president of McQuillan Consulting in Cambridge, MA, remarks that end-to-end ATM networks are not available and might never reach that goal. He further observes that IP has advantages in many networks, expects shared and switched Ethernet network deployments to increase, and advises ATM developers to focus on areas where ATM capabilities excel.

And even gigabit speeds are being challenged by Ethernet supporters. Last month, the Gigabit Network Alliance was formed by 11 leading semiconductor, communications and computer companies. Its vision is to advance the adoption and standards for achieving gigabit Ethernet technology over fiber and copper and to introduce products by 1998.

To avoid deployment slowdown like ATM`s, fiber-optic technology and product and standards proponents must not focus on technical superi ority: They must target user acceptance as the ultimate market-ruling determinant. q

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