Feature: Layer upon layer upon layer gets to core user needs

"The advent of the Layer 3 switch is what made frame networks at the core possible," said Basil Alwan, US-based vice president of product management at Bay Networks. "You get one of the main benefits of ATM -- you can switch or route equally fast. That has important implications for how you can build networks."

Switching is one of the euphemisms that abounds in the politically correct 1990s as people use words to evade reality. Layer 2 switches are really multiport bridges, but routing was in, and the 'B' word was out when the EtherSwitch was christened in 1990. Similarly, the 'R' word had become synonymous with slow, complex and expensive by the mid-1990s when the first Layer 3 switches -- really hardware-based routers -- appeared.

"ATM had an opportunity and blew it," asserts Brendan Hannigan, an industry analyst with Forrester Research. "It's too complex and too expensive." A lot of piloting is going on this year on similar projects, and analysts expect backbone upgrades to go into full swing in 1999.

"In two to three years, the core of the network will be routing switch-based, not router-based," he said.

The new generation of products has pushed the envelope out enough that bandwidth and prices are not a big story any more. "We're getting to the point where real value is not bigger and faster but more intelligent and more software-aware," said Fred McClimans, chairman and CEO of Current Analysis. Instead, the focus should shift to incorporating services -- directories and firewalls, for example -- into the switches.

"The big emphasis will be on prioritisation," McClimans said. "Not for video or voice, but to make sure that your SAP/R3 traffic gets through no matter what else is going on."

Increasingly, management tools should be leveraging directory services. To date, network management has really been device management. "Now you can manage class of service and QoS (quality of service) and align management policies with the particular needs of your business environment," said Clint Ramsay, vice president of marketing for 3Com's enterprise systems division.

In the Infonetics survey of high-speed LAN users, three quarters of respondents said they would require QoS capabilities by 2000. However, most of them plan to provide it by over-provisioning their networks. While QoS gets a lot of hype from vendors, it doesn't seem to be much more than a check-off item for users right now. "We're not looking at QoS, but rather at using policy-based management to control access to network resources," said Frank Bielecki, network manager at Sandia National Laboratories.

A number of experts expect this functionality to be provided through Directory Enabled Networks (DEN).

"This is a radical new approach to managing bandwidth," said Sam Alunni, a vice president at Sterling Research. Policies are established in a single directory that switches can access. The switches provision network resources based on profiles set up for users and applications.

"With DENs, you start to get the same degree of control over frame-based networks that you used to have to go to ATM to get," Alunni said.

Networks should also get more reliable as functions are moved into silicon and there are fewer parts. After all, the network component that fails most often is the routing software.

"As network availability approaches the 99.99 per centrequirement of the Bellcore Network Equipment-Building System standard, it will enable business-quality voice over IP and finally unlock the tremendous potential of computer-telephony integration. Layer 3 intelligence will get more democratic as well. It is expected to spread to the wiring closets and even out to the edges as WAN links go beyond E-1 speeds.

"Intelligence is getting cheap, so put it in the closet," said Douglas Hill, co-founder of Xylan. When desktops are attached to Layer 3 switches, all sorts of possibilities open up.

These include user-authentication capabilities that enable the network to reconfigure itself based on the identity of the user; end-to-end QoS; and much more granular directory-enabled networking and intelligent multicast distribution.

Vinod Bhardwaj, the inventor of the first Ethernet switch, can see carrying things even further by putting a router at every port and eliminating Layer 2 altogether. Assuming the world converges on IP and silicon prices continue to fall, he thinks it could happen in three to four years.

"Routing is a superset of switching, so it has everything the network requires," said Bhardwaj, now president and CEO of ControlNet, a high-speed networking start-up. "You would just need a NIC and a router."

Bhardwaj's vision isn't out of the realm of possibility. In fact, it dovetails nicely with the TCP/IP protocol stack, in which Layer 2 is equivalent to OSI's Layer 3 and there is no separate data-link layer. First, though, the routers will have to get a lot more intelligent, said Mary Petrosky, senior analyst at The Burton Group. Otherwise, the configuration and administration of all those routers would be prohibitive.

"In ATM, if you have a network with some 155Mbit/sec switches and you drop a new 622Mbit/sec box into the core, they will all find each other and update their tables and learn the new topology," Petrosky said. "Routers don't do that at this point."

Self-configuring routers that can fit into a single switch port at an affordable price? They're not exactly on the horizon, but with the speed at which switching has progressed thus far, who would say it can't happen?

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