Gigabit Ethernet MANs: Where the real action is

By Mary Petrosky
Network World, 10/04/99

While 1000Base-T was all the rage at NetWorld+Interop '99 Atlanta, it's the fiber-based versions of Gigabit Ethernet that will have the most dramatic impact on the market.

It has long been acknowledged that Ethernet owns the desktop. The availability of inexpensive Gigabit Ethernet connections running over Category 5 copper will cement Ethernet's dominance of the LAN. However, Gigabit Ethernet over long-haul fiber will take Ethernet where it has never gone before - into WANs and metropolitan-area networks (MAN).

Ethernet will give ATM, SONET and other traditional MAN technologies a run for their money over the next several years, particularly for data-oriented applications. Gigabit Ethernet's low cost and ease of operation relative to other MAN technologies make it appealing to enterprises that want to extend their LANs across a metropolitan or wide area.

The Gigabit Ethernet MANs deployed to date have been private networks. However, at least one start-up plans to change that by testing public Gigabit Ethernet MAN services later this fall. Certainly private Gigabit Ethernet MANs offer their users benefits, but the market for Ethernet-based MANs will really take off when public services are readily available, which could be as soon as 2001.

3Com, Foundry Networks and Cisco are among the vendors that have worked with customers and service providers to create private Gigabit Ethernet MANs. In general, the customers have access to dark fiber. For example, 3Com recently helped a municipality extend its LAN over several miles using fiber-based Gigabit Ethernet. In contrast, a Korean service provider has been offering private Gigabit Ethernet MAN services based on Foundry switches for nearly a year.

For its part, last month Cisco announced an alliance with Metromedia Fiber Network (MFN) that will enable enterprises in key cities to extend their Ethernet LANs over private MANs using MFN's dark fiber infrastructure and Cisco's Catalyst switches. MFN is building fiber infrastructures in major U.S. metropolitan areas, including Chicago, Dallas and Washington, D.C., as well as cities in Canada, Germany, Holland and the U.K.

Gigabit Ethernet's use in MANs and even WANs will have even greater appeal when public services become available. Unlike suppliers of private MAN services, public service providers offer customers equipment, security and operational support. An official at one as-yet unannounced Ethernet MAN services start-up noted that customers will get roughly twice the bandwidth of a T-3 connection for half the cost once the company's services go live next year.

Currently, there is no IEEE standard for operating Gigabit Ethernet over long distances. However, a group of vendors is developing a long-haul fiber-optic Gigabit Ethernet technology, informally dubbed 1000Base-LH. This technology can operate at distances of up to 70 kilometers, depending on the lasers used. Vendors have made it easy for customers to use 1000Base-LH by providing a standard interface known as the Gigabit Interface Converter (GBIC).

Ethernet's use in MANs - and potentially WANs, longer term - is being helped along by other industry efforts, some channeled through the IEEE. Key vendors have helped form the 802.3 Higher Speed Study Group to investigate pushing Ethernet to 10G bit/sec. Ethernet's ability to continue to scale in terms of bandwidth is crucial to its long-term viability in multiple markets, particularly compared with ATM.

Currently, carriers and service providers are the main targets for this technology, which has led to debate over what the actual speed should be. WAN equipment makers would like the speed to match OC-192 SONET (9.58G bit/sec), thus allowing them to use existing technology and presumably reduce the cost and complexity of connecting Ethernet LANs to MANs and WANs. Because the IEEE has not yet authorized this work, it's unlikely there will be a standard for 10G bit/sec Ethernet before 2002.

Other efforts under way within the IEEE will boost Ethernet's scalability and reliability, making it feasible to deploy the technology in larger networks. For example, the 802.1w rapid reconfiguration specification, which could be completed late next year, would reduce the reconfiguration time of spanning tree networks from tens of seconds to tens of milliseconds.

Even with such advances, Ethernet still won't be as resilient as SONET or ATM. Although some industry players would like Ethernet to evolve to be more SONET-like, others want Ethernet to remain the relatively simple technology it has always been. Indeed, Ethernet's simplicity has been its key strength. Let's hope those pushing Ethernet into its new MAN/WAN role don't lose sight of that.