Boosting Bits Across the Network

Boosting Bits Across the Network

With network usage growing exponentially and multimedia technologies becoming corporate mainstays, most CIOs are suffering from bits on the brain. Undeniably you need high-speed data networking solutions that are both cost-effective and easy to implement. But with multiple technologies slugging it out in the marketplace, finding the right solution for a particular application can be tricky. Pick the wrong technology and you can find yourself stuck with a network that's too slow -- or worse, a hefty bill that attracts the wrong sort of attention from your CFO.

High-speed data networking encompasses two general areas: the 100Mbps (megabits per second) field, where fast Ethernet tangles with 100VG-anyLAN, and the faster-than-100Mbps segment, where asynchronous transfer mode (ATM) and gigabit Ethernet are battling for market dominance. (For more on how fibre-optic technology is helping CIOs send data faster and cheaper see "Making Fibre Faster".) Frequently, each of these technologies has a specific niche, but it's important to discern where not to install one or the other.

The first step in selecting between high-speed network technologies is in-depth research, says William Flanagan, program director for NetReference, a US network consulting and research firm. "There's no easy way of doing this." Only after comparing the technologies side by side -- projecting how each will meet specific needs and fit into the organisation's networking framework -- can you select the right solutions. "You're going to have to read a lot of white papers and vendor literature. And you're going to have to do a lot of thinking," he says. "You need to know the advantages and disadvantages of each technology in terms of quality of service, management and compatibility."

As the data networking field moves into the new millennium, familiar technologies -- enhanced to handle faster speeds -- are winning over radical approaches. And even though we're witnessing a convergence of data and voice technologies at the carrier level, these network technologies can be called on to carry multimedia content when necessary. Still, these networking technologies warrant a careful comparison. "We're witnessing the end of your father's data network," says Flanagan.

Gigabit Ethernet Versus ATM

Earlier this decade, experts predicted that ATM would emerge as the dominant high-speed networking standard for both LANs and WANs. The technology provides support for data, voice and video connections at access speeds of either 155Mbps or 622Mbps, depending on the needs of a specific application, and can also support phone company line speeds as fast as 2.5Gbps. But ATM's supporters failed to anticipate the arrival of Gigabit Ethernet, a more familiar technology that's always available at a lower cost than ATM. According to the Gigabit Ethernet Alliance, in 1998 the per-port price of a Gigabit Ethernet switch was between $US1850 to $US2800, compared with $US4200 for a 622Mbps ATM switch.

Gigabit Ethernet, a 1000Mbps technology, began hitting its stride about a year ago when Cisco Systems jumped into the field, an action that removed lingering doubts about the technology for many potential customers. The company joined Nortel Networks, 3Com and several other firms in the market. According to Dataquest estimates, revenue from Gigabit Ethernet switches, which connect data networks together, jumped from $US93.1 million in the third quarter of 1998 to $US211.4 million in the first quarter of 1999.

While Gigabit Ethernet is a viable technology in its own right -- the first IEEE 802.3z standard defined its use over optical fibre, and a 1000Base-T copper cable alternative became a formal standard last June -- it also has a strong psychological factor working in its favour, says John Matthews, a principal consultant with Ovum, a London-based technology research firm. "People are familiar with Ethernet, so when they think about Gigabit Ethernet they view it as a natural evolution from what they've been doing."

On the other side, ATM's supporters trumpet its advantages. Instead of promoting speed, its advocates frequently focus on the technology's flexibility, reliability and management attributes. Most believe that ATM's greatest strength lies in its quality of service (QoS) support. ATM's QoS lets customers prioritise traffic down to the end user. Gigabit Ethernet, on the other hand, offers only something called a Resource Reservation Protocol (RSVP) for QoS, a technology that pales in comparison to ATM's capability, according to Ovum's Matthews. "RSVP doesn't guarantee QoS the way that ATM does." ATM also permits the implementation of permanent virtual circuits (PVCs), allowing organisations to dedicate a portion of ATM's bandwidth between two points. "This feature provides the user with more flexibility in bandwidth management," says Matthews.

ATM and Gigabit Ethernet each have their roles in high-speed networking, says Robert Currier, director of data communications for Duke University in Durham, North Carolina. Currier uses ATM to link to Internet backbones and other off-campus connections, while using Gigabit Ethernet for campuswide links. "Within the campus, we elected not to use ATM because of the cost both in terms of capital investment and operations." Currier estimates that installing ATM on the campus would have nearly doubled his hardware costs. It also would have meant spending an extra $US200,000 per year to hire network specialists to handle the technology, a cost he was able to save by relying on the skills of less highly paid Ethernet professionals. He notes that it can be complicated to keep people trained and up to date in ATM. "There's a much larger available pool of skilled Ethernet experts," he notes.

Although Gigabit Ethernet hasn't yet made a major impact on very large WANs -- you won't find a Gigabit Ethernet link between the United States and Europe, for example -- the situation may soon change. Ethernet is currently going through an evolutionary process, with standards being set for a 10Gbps technology that would far exceed ATM's top speed.

Jack Wimmer, the Texas-based vice president of network technology and planning for MCI Worldcom, says Ethernet-based technology may ultimately provide a medium for virtually all high-speed networking needs. "Some of the advanced work we're doing is looking at the integration of 10Gbps Ethernet technology with other networking technologies to see whether we could provide an even more cost-effective solution for customers that have very high bandwidth needs."

100VG-anyLAN Versus Fast Ethernet

Just as Gigabit Ethernet is triumphing over ATM in many situations, Fast Ethernet is winning the battle against 100VG-anyLAN in the 100Mbps networking arena. Actually, according to most observers, the battle has already been won by Fast Ethernet.

Developed by AT&T Microelectronics, Hewlett-Packard. and IBM in the mid-1990s in an attempt to grab a foothold in the booming network marketplace, 100VG-anyLAN was positioned as a networking technology that could handle high-speed multimedia streams with ease.

The technology includes a Demand Priority protocol that allows time-sensitive applications, such as video, to be given priority network access, resulting in reduced break-up of multimedia streams. Demand Priority also allows network managers to give timing-sensitive applications priority access to the network, such as the MD's motivational speech to the troops.

But these features, while useful, haven't helped 100VG-anyLAN derail loyalty to the Fast Ethernet juggernaut. As in the ATM versus Gigabit Ethernet battle, user comfort and familiarity have turned the tide in favour of Ethernet. Because Fast Ethernet is so similar to Ethernet, it doesn't require users to learn the intricacies of a new technology. Bruce Tolley, manager of business development for 3Com (US) and a vice chair of the Gigabit Ethernet Alliance, notes that Ethernet users can easily phase in higher-speed links as needed. By comparison, 100VG-anyLAN's Demand Priority access method requires smart hubs, adding an extra layer of complexity and expense.

Although Hewlett-Packard continues to offer 100VG-anyLAN products, the company admits that the market is moving away from its technology. "The bulk of customers are really going toward Ethernet solutions," says Darla Sommerville, product marketing manager for HP's ProCurve Networking unit (US). She notes that HP now offers Fast Ethernet products as well as 100VG-anyLAN solutions.

In fact, HP has settled on Ethernet as its foundation for enterprise networking. The company is emphasising high-speed switching across Ethernet segments (as opposed to slower "store and forward" technologies to route packets between segments) as a solution for the convergence of data, voice and video. "Most people are opting for switched 100Base-T solutions because of the performance and support for applications, such as multimedia, that demand quality of service," she notes.

At Women & Infants' Hospital in Providence, Rhode Island, Fast Ethernet technology is used as the backbone for the LAN connecting 11 buildings over a 10-block area, says David Porter, the hospital's senior LAN/WAN specialist. Although most of the facility's desktops, printers and other endpoints are interconnected with 10Mbps Ethernet, a gradual rollout toward 100Mbps Ethernet where it is necessary is under way. The extra speed will allow the network to support a growing administrative workload: Women and Infants' handles close to 9000 births each year.

Porter says he never seriously considered using 100VG-anyLAN technology. "Fast Ethernet fit the bill, since it provides the speed and overall compatibility we require." Porter's future plans include a Gigabit Ethernet, ATM (already part of the hospital's wide area network) or hybrid backbone link. The technology will allow Women and Infants' to share voice, video and data with other hospitals. "Network technology is advancing at a rapid pace, and we're always on the lookout for things that will help us operate better and more cost-effectively. In this field, the planning never stops."

Other Network Considerations

In the world of high-speed networking, selecting the right vendor is almost as important as picking the right technology, particularly when dealing with a rapidly evolving area like Gigabit Ethernet. Says analyst Flanagan, "Many vendors have announced products, but not all vendors have started shipping in volume."

Flanagan adds that some vendors have a track record and can provide customer references, while others are still trying to establish market footholds. "You have to be careful," he warns, "because caution and new technologies should always travel hand in hand."

Making Fibre Faster

A new technology extends the reach of high-speed networks FIBRE-OPTIC NETWORKS While most high-speed data networks are still based on copper cables, the number built with fibre-optic technology is growing rapidly. Compared with copper, fibre-optic cables are thinner and lighter, are less susceptible to interference and offer much greater bandwidth -- which lets networks carry data at faster speeds. Now a new technology is making fibre even speedier.

For the past several years, fibre-optic communications has relied on synchronous optical network (SONET) technology. As a transmission system for high-speed digital traffic, SONET speeds range from 51.8Mbps to 13.2Gbps. SONET is an intelligent system that provides advanced network management and a standard optical interface. It uses a self-healing ring architecture that's able to reroute traffic if a line goes down. SONET backbones are widely used to aggregate lower-speed T1 and T3 lines.

SONET technology, however, is now being challenged by wavelength division multiplexing (WDM), a new technology that uses multiple lasers to send several light signals simultaneously over a single optical fibre, thereby making more-effective use of fibre cables. WDM, or DWDM (dense WDM), as the technology is often called, can transmit up to 32 channels over one fibre, at 2.5Gbps per channel, and is expected to support up to 128 channels in the near future.

Most major telecommunications vendors have jumped on the DWDM bandwagon in the past year. Nortel Networks, for example, is touting its metro network-oriented Optera line, which it acquired when it bought Cambrian Systems late last year. Lucent Technologies offers metro DWDM, which is designed to add extra bandwidth to local networks. Cisco Systems has introduced something called Dynamic Packet Transport technology, which gives Cisco's routers the ability to turn electrical signals into wavelengths of light as well as to restore service within millionths of a second in the event of fibre cable cuts or equipment problems.

-- J Edwards

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