One layer at a time. Layer 3/Layer4 continues to crawl, bandwidth holds biggest attraction
By Paul Korzeniowski.

What's the rush? That's what network managers seem to be saying to switch vendors these days. Just when the vendors have jam-packed routing features into their Layer 3/Layer 4 switches, all network managers are interested in is adding the new devices for their wire-speed bandwidth. They can leave the rest.

Take the engineering school at the University of Oklahoma. When it opted for Layer 3/Layer 4 switches before classes started in the fall of 1998, bandwidth was the driver.

The bandwidth was needed to support students' purchases of notebook computers. Today, some 2,200 students access application code and other useful classroom information from a series of Compaq Alpha servers running Windows NT.

The backbone that supports the school's automation effort includes 10 switching routers, one BigIron 4000 and a TurboIron/8 switching router-all from Foundry Networks Inc. The new equipment lets the university set up distinct LAN segments, route information between them and improve bandwidth utilization-functions typically performed by a router. Yet, this capability now lies dormant and users exchange information on one large network.

"The main reasons why we purchased the switches were to add more bandwidth and flatten out our network, which we have done," says James Henderson, network operations and help desk manager at the university. "We haven't really determined yet whether we will use any of the routing functions."

It's a case of vendors over anticipating corporate needs and the reason implementation of Layer 3/Layer 4 features is moving at a snail's pace. The routing capabilities vendors touted in their Layer 3/Layer 4 switches for the past two years or more are still an afterthought to customers, most of whom are content to rely on switches for Layer 2 functionality. What they really like about the higher-layer switches is their increased bandwidth: Gigabit Ethernet switches offer customers a tenfold performance improvement.

The routing functions-combined with switching in Layer 3/Layer 4 switches-appear to be more of a nice amenity rather than a prime purchasing criterion. Whereas routers usually rely on software running on their internal processors to move information from one network to a second, Layer 3/Layer 4 packets are routed completely with internal hardware, which can speed performance. And the devices operate at wire speed, meaning millions of packets per second vs. the tens of thousands of packets per second found with traditional routers. Better still, the switches can cost one-tenth as much as a router.

Router Redux
With all these benefits, it's no wonder that vendors, analysts and some customers expected the new devices to quickly eat into router sales. But the end of routers never materialized. In fact, revenue derived from routers grew more than 19 percent in the third quarter of 1998 to $1.6 billion and reached $7.2 billion for the year, according to Dataquest.

"Companies are expanding the number of remote users in their organizations and need more routers to support them," says Steve Collen, director of marketing for Cisco's Enterprise line of business.

What the data shows is that Layer 3/Layer 4 switches are still an emerging technology that accounts for only a small percentage of overall switch sales. Dataquest found that suppliers shipped $188 million worth of Layer 3/Layer 4 devices in the third quarter of 1998, the first quarter significant numbers were available. The figure is a mere 9 percent of the total switch revenue for that quarter.

Because they are new, the switches do not yet offer as many features as routers, which stops some buyers short. And, although Layer3/Layer 4 switches work well enough in LANs, they weren't designed to move information across WANs.

Switch suppliers are trying to add WAN features such as Sonet interfaces to their products, but not everyone thinks that is such a great idea. "LAN and WAN traffic have distinct characteristics, so routers will always be much better suited to WAN connections than switches," explains David Passmore, a principal at consultancy NetReference Inc.

And there's another glitch: Routers can move information among devices working with a wide range of network protocols: IP, AppleTalk, SNA, NetBIOS and IPX. Most Layer3/Layer 4 switches limit routing functions to the IP protocol-so a company cannot use them to move information from an AppleTalk network to an SNA segment.

IP Limitations
Siemens Business Services Inc. found out about the IP limitations when the company decided to upgrade its network in early 1998. The company-which offers outsourcing services-op-erates a central data center in Toronto that houses a wide range of servers: IBM mainframes, a variety of Unix servers and PCs running Microsoft's Windows NT operating system. Siemens wanted the Layer 3/Layer 4 features because it needed to route information across several different LAN segments.

Essentially, the company wanted to upgrade its network-which offered 10-Mbps Ethernet to the desktop and a 100-Mbps FDDI backbone. Siemens talked with Cabletron, Cisco, Nortel Networks and 3Com about replacing the backbone network with Gigabit Ethernet switches.

Siemens narrowed the candidates to Cabletron and Nortel because both companies seemed further along in product development. But since the Nortel switch offered only IP routing, Siemens went with Cabletron's product, which offered IP and IPX initially with AppleTalk and SNA expected later.

The company started making the transition in the summer of 1998, but has encountered a few bumps. "We expected the switch's routing functions to operate like those in our Cisco routers," explains Rafael Sapriani, a network systems consultant at Siemens. "But they don't, so there has been a learning curve as we determined how to configure the system."

For the most part, adapting to the new system was a training issue: The company's technicians had to learn how to operate the routing functions in the switch. The routers also can filter network transmissions at finer levels than switches.

But this kind of learning curve could be hindering other companies from exploiting Layer 3/Layer 4 routing functions, too. Many are placing new switches in their networks one layer at a time-first with Layer 2 capabilities, getting the systems stable, then slowly turning on the routing functions.

For instance, Pacific & Orient Insurance has 500 employees working at its main offices in Kuala Lumpur, Malaysia. In the spring of 1998, the company began a massive computer and network upgrade. About 50 users worked with shared 10-Mbps Ethernet connections, but the rest relied on legacy terminals and remote controllers to access information stored in an NCR Corp. computer running the PICK operating system.

The insurance company upgraded to desktop computers running Microsoft's Window 98 with access to information stored in IBM RS/6000 and Hewlett-Packard PC servers running Windows NT.

Because more information is transmitted among employees, the company needed a high-speed network and talked with Lucent Technologies, Nortel and 3Com. In the end, Pacific & Orient selected Lucent's P550 Cajun Gigabit switch not for its Layer 3/Layer 4 features, but because it offered the highest degree of fault tolerance. "If our network went down for any reason, we would lose $100,000 per day," says Michael Hannigan, director of marketing at Pacific & Orient. Lucent's P550 Cajun switch includes duplicate fans, power supplies and switches; all hardware components can be changed while the switch is running.

Pacific & Orient installed the switch last spring along with Nortel's BayStack 350T Fast Ethernet switches on two floors at the main office. The Malaysian network operates as a single system with a frame relay connection to its technical support staff in New York.

"Eventually, we plan to start running voice over the network, so we will need to implement the routing functions. But now we are not using them," Hannigan says.

Implementing Layer 3/Layer 4 features can be difficult. A network manager must examine how users transmit information across a network, then decide which protocol should be supported on each network segment and ultimately configure all the switches so there is minimal broadcast interference. The bottom line is increased administrative complexity-never a selling point with busy network managers.

Inertia is another issue: Few network managers are willing to pull out all of their routers. Nor do they want to give up the familiarity of troubleshooting a routed network in favor of an environment where switches make routing decisions, a setup that can make network troubleshooting difficult.

Another problem is that Layer 3/Layer 4 switches are expensive, costing $500 to $1,000 per port, compared with a few hundred dollars for a Layer 2 switch. "Because the switches were new, we didn't see any price drops in 1998," says Rick Lougee, a product line manager at Nortel.

As a result of all of these factors, corporations are deploying Layer 3/Layer 4 switches only in select locations. The bulk of corporate users work with switches placed in wiring closets, usually on each floor in a building. The problem is that Layer 3/Layer 4 switches are too expensive to be placed throughout an entire organization.

Instead, they are gaining acceptance in data centers where they move information among groups of servers. In certain cases, suppliers have positioned their products more as replacements for traditional data center systems-such as load balancers-rather than as replacements for routers.

Most often it's not an either/or decision: The new switches complement rather than replace routers.

"Companies are putting Layer 3/Layer 4 switches in front of their core routers, letting the switch speed network throughput, and still relying on routers to move information among different network segments," explains NetReference's Passmore.

In that case, the snail just may pick up the pace later this year.

Paul Korzeniowski is a freelance writer based in Sudbury, Mass.

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