The Ethernet encore: Higher speed

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At one time, 10Mbps was considered Ethernet’s top speed; but engineers have consistently found ways to boost the top speed and push the technology into new niches. The 10Gbps Ethernet initiative places the technology in wide area networks (WANs), an area now dominated by SONET multiplexers and Asynchronous Transfer Mode (ATM) switches. This article discusses the development of 10Gbps Ethernet and its potential impact on enterprise networking.

On the cutting edge

Utfors, AD (a Stockholm, Sweden Competitive Local Exchange Carrier [CLEC]), took a close look at its backbone network in the summer of 1999. As the firm rolled out new Digital Subscriber Line (DLS) and Ethernet services to residents and businesses, the carrier needed more bandwidth than its Gigabit Ethernet links could carry. While SONET was a possibility, the carrier instead opted for 10Gbps Ethernet. “We think that 10G Ethernet will enable us to deploy new backbone network technology more easily and at a lower cost than alternatives,” said Sten Nordell, chief technology officer at Utfors. The decision put the CLEC at the forefront of the next Ethernet wave.

“Because of the success with previous efforts to speed up Ethernet’s top transmission speed, 10G Ethernet is generating a lot of buzz right now,” stated Eric Thompson, an industry analyst with Dataquest Inc. (San Jose, California), a market research firm. Although the emerging 10Gbps Ethernet technology has a great deal of potential, it is an early stage of development. The standard is just beginning to be crafted, and the process won’t be finished until 2002. Yet, vendors are moving quickly and plan to deliver the first wave of 10Gbps Ethernet switches during the second half of this year.

Analysts expect rapid adoption of these products because of Ethernet’s unceasing momentum. The technology first emerged as the de facto method of moving information from a user’s desktop to a server. Fast Ethernet, which operates at 100Mbps, pushed the networking option into the data center, where it is used to move information from switches to servers. With the acceptance of Gigabit Ethernet, the technology became a prime backbone system, moving data among a series of departmental LANs.

Ethernet’s successful track record

Ethernet has been successful for a couple of reasons. The networking technique has a relatively simple design and therefore is much less expensive to deploy than alternatives. Historically, vendors have been able to dramatically decrease pricing as volume shipments ramped up: For example, the average per-port price of a Gigabit Ethernet connection started at $1,700 in 1997, dropped to $1,200 in 1998, fell further to $880 in 1999, and is expected to reach $540 this year.

Network technicians have also learned how to manage Ethernet connections; and extending Ethernet to other venues simplifies network management. Network operators can use one network management system to monitor a number of connections rather than be forced to work with a number of different systems–one for LAN connections, one for servers, one for backbones, and one for WANs.

Such benefits are expected to again prove enticing with the higher-speed option. 10Gbps Ethernet will enable Internet Service Providers (ISPs) to deploy high-speed links between carrier-class switches and routers at a relatively low cost. In the enterprise, this option will enable network managers to scale their packet-based networks from 10Mbps to 10Gbps and leverage their existing Ethernet investments as they increase network performance.

The IEEE 802.3ae Task Force

Work on the high-speed version began in March 1999. The Institute of Electrical and Electronic Engineers (IEEE), which oversees Ethernet developments, then formed the IEEE 802.3 Higher Speed Study Group (HSSG) to study 10Gbps Ethernet. The IEEE made it a formal undertaking (dubbing it the 802.3ae standard) in November, and authorized the creation of the 802.3ae Task Force in January 2000.

To boost Ethernet’s top transmission speed from 1Gbps to 10Gbps, the group has to address a handful of issues. The task force must develop standards for physical-layer chipsets for LAN and WAN connections. These chips, called transceivers, are a key component in sending and receiving data signals over a network. The group decided to develop two new standards: one 10Gbps rate for the LAN and an OC-192 (9.6Gbps) rate for the WAN.

Distance is another issue. “Because the first uses of 10G Ethernet will be in the WAN, vendors needed to increase Ethernet’s maximum distances from hundreds to thousands of feet,” said Val Oliva, a product marketing manager at Foundry Networks Inc. (Sunnyvale, California), a network switch supplier. “Before, the technology was used largely in server farms where distance is not as much of an issue.”

The task force is crafting single-mode and multimode fiber-optic 10Gbps Ethernet standards. The single-mode media will handle long-distance traffic and operate at distances up to 40 kilometers, whereas the multimode fiber is designed for short-haul data and works at distances up to 300 meters. Initially, the choices will be limited to fiber wiring because no one has yet discovered a technically feasible way to handle such high speeds over copper lines.

The standard is expected to be an end-to-end, full-duplex, full-frame protocol. Earlier versions of Ethernet were half duplex, meaning transmissions flowed only one way. Full-duplex connections are needed because so much data is being transmitted.

The task forced examined changing Ethernet’s framing technique, which packages information in 1,500-byte frames. As users send larger amounts of information over networks, some vendors saw a need to package information in larger packets. When Gigabit Ethernet emerged, suppliers such as Alteon Websystems Inc. (San Jose, California) put information in Jumbo Frames, which rely on 8,000-byte frames.

However, the IEEE decided to stick with the original framing technique. “No one wanted to develop a specification that would be incompatible with the current base of Ethernet equipment,” said Bruce Tolley, marketing manager at Cisco Systems Inc. (San Jose, California).

Although the framing issue has been resolved, there is still debate about how to address the other issues. The IEEE expects to sort through them quickly and deliver a first draft of the 10Gbps Ethernet specification in September 2000. Members hope to send a final draft for member approval in March 2001 and have the full specification adopted a year later.

Rapid product development

With interest in the standard growing, vendors are trying to speed up the product development process. In February, a group of seven vendors including 3Com Corp. (Santa Clara, California), Cisco; Nortel Networks Inc. (Santa Clara, California), and Sun Microsystems Inc. (Palo Alto, California) formed the 10 Gigabit Ethernet Alliance (Mountain View, California). Its mission is to supplement the IEEE 802.3 10 Gigabit Ethernet standards process by promoting interoperability demonstrations and compliance testing mechanisms–duties outside the IEEE’s jurisdiction.

Vendors expect to deliver pre-standard products in the second half of this year; however, members are debating how the technology will be priced. Historically, network equipment suppliers have been able to deliver new Ethernet products that offer 10 times as much bandwidth at only 2 to 3 times the cost of top-of-the-line products. Cisco’s Tolley thinks this is a reasonable goal, but Carlos Zaidi, a business and marketing manager at Nortel, does not. “Since the first use of 10G Ethernet will be in carrier core networks, one should not compare it with traditional LAN-based pricing, since LANs are much less complex,” he said.

But the vendors do agree on who will be most interested in the technology initially. One of the first applications for 10G Ethernet could be carrying multiple, aggregated Gigabit Ethernet lines from service provider point-of-presence to core routers. This usage will move the technology into direct competition against the likes of ATM switching and SONET multiplexing. These techniques are well understood and have proven they can support carriers’ high-reliability and high-speed requirements.

Important benefits

Although questions remain about whether Ethernet will be able to do the same, its big selling point is simplicity. With about 95 percent of IP traffic originating in Ethernet nodes, network management becomes simpler when there is no need to translate transmissions from the desktop to the backbone to the WAN. In addition, vendors have been adding features–such Multi Protocol Label Switching (MPLS)–so Ethernet can carry video and voice traffic as well as data transmissions. This change enables managers to combine autonomous data, video, and voice networks.

Such benefits were among the reasons Utfors decided to become an early adopter of 10Gbps Ethernet. The company opted for Nortel equipment because it already relied on the company’s Gigabit Ethernet products. In 2000, Utfors expects to complete a 6,500-kilometer fiber backbone network and connect 50 Scandinavian cites including Copenhagen, Oslo, and Helsinki. The carrier, which has more than 250,000 customers and 150 employees, plans to use Nortel’s Accelar routing switches, Versalar Switch Router 25000, OPTera Packet Core high-speed Ethernet system, and Preside network management system for the network.

The carrier is now at the leading edge of 10Gbps Ethernet deployment, but it won’t be there for long. Dataquest estimates that sales of 10Gbps Ethernet products will rise from $71 million in 2001 to $3 billion by 2003. “Carriers are now grappling with problems of how to deliver high-speed connections to businesses and consumers,” concluded Dataquest’s Thompson. “10G Ethernet has the potential to solve that problem by offering them a low-cost, easy-to-deploy option.” //

Paul Korzeniowski is a freelance writer in Sudbury, Mass., and specializes in networking issues. His e-mail address is

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