More than 10 years after its adoption as an industry networking standard, Ethernet is about to experience its biggest facelift yet. In an industry-wide effort driven by the insatiable demand for more bandwidth, Gigabit Ethernet will be implemented next year in millions of switches, routers, and servers that will start moving traffic at 1,000 Mbps, or about 100 times the speed of standard Ethernet. Grand illusions of an upgraded, high-speed Internet may be misguided, however, since the new technology is primarily designed for local area networks, or LANs, and not for long-distance feeds. The improved Ethernet will, however, give network administrators the capacity to extend local networks to more users, who will see faster transmissions of internal data communications.
Mirroring the speed of the technology itself, the Gigabit Ethernet standard has moved from draft specification to reality at a remarkable pace. The Institute of Electrical and Electronics Engineers ratified the second draft of specification 802.3z in November of 1996, and already multiple vendors have hardware - switches, routers, network interface cards, and protocol analyzers - based on the updated version.
"If you had asked me two years ago if Ethernet would ever get beyond 100 Mbps, I would have said no," said Steven Burt, an engineer at Cisco Systems. "The Gigabit Ethernet standard is so well defined and so well followed that the problems that plagued the first 100-Mbps products aren't present, even in our prototypes."
The standard is expected to be finalized in the first quarter of 1998, and vendors anticipate providing Gigabit Ethernet hardware to resellers in the second quarter of 1998.
Most of today's Ethernets run at 10 Mbps, with Fast Ethernets moving at 100 Mbps. Both run over standard unshielded twisted-pair copper wire of Category 5 grade - a classification that refers to the quality of the wire. Although Gigabit Ethernet currently runs only on fiber-optic cable, a Category 5 copper implementation is in the works, which will make it easier to upgrade a 100 Mbps network to 1 Gbps. This points to one of its advantages over ATM - a long-distance, high-speed networking technology - because having the physical infrastructure in place makes upgrading networks mostly a matter of updating the switching hardware.
The Gigabit Ethernet Alliance, a nonprofit working group sponsored by the Gigabit Ethernet vendors, is another reason for the accelerated development of the technology. Its purpose is to create a non-competitive forum where standards can be hammered out and vendors can keep up with technological developments and maintain communications to ensure the interoperability of competing products.
"Six months from drawing board to implementation is impressive to begin with, but to have this many vendors interoperating, and to have so much test equipment available when the standard hasn't even passed beyond the second draft, is nothing short of amazing," said Bert Armijo, a representative for the GEA, who at the time was leaning on a rack of experimental gigabit routers.
When it arrives, Gigabit Ethernet will be found mostly in server closets and machine rooms. But as the implementation of 100-Mbps desktop networks becomes wider (for now, these connections usually are used to link multiple 10-Mbps networks together), switched 100-Mbps networks will emerge, and Gigabit Ethernet will become the obvious choice for interconnecting 100-Mbps switches. An Internet bandwidth solution?
Gigabit Ethernet is not going to fix the Internet's bandwidth woes. Today's high-speed, long-distance backbones generally use Asynchronous Transfer Mode technology to achieve transmission rates of up to 653 Mbps. ATM is a widely deployed WAN technology, and although it works on a LAN, it is not especially designed to do so. Figures like 10 Mbps and 1 Gbps measure theoretical throughput of a network (how much data can be carried in one second of time when the wire is at capacity). Latency (usually measured in milliseconds) is a measurement of how long it takes data to hop from point to point, with lower latency times indicating a faster network.
Ethernet, partially because of its shared-wire architecture and periodic collisions, is plagued by latency problems. A latency time of 10 to 15 milliseconds is not uncommon on a typical 10-Mbps Ethernet, and if a packet needs to cross several routers or collides with another packet on the wire, it takes significantly longer to reach its destination. So although Gigabit Ethernet has 10 times more throughput capacity than a Fast Ethernet, latency times are not significantly reduced. ATM, by contrast, is an extremely low-latency protocol, with latency times often measured in microseconds, even on wide area links.
Network administrators, who are often wary of integrating new technology into mission-critical applications, are already examining how Gigabit Ethernet could be useful.
"When they get it running over copper, we will probably replace several of our hundred-megabit [Ethernet] backbones with gigabit as soon as the hardware is made available," explains Rob Deker, a network administrator for Digex, a major East Coast ISP.
Marilyn Callaghan, a consultant to the Gigabit Ethernet Alliance, said a user survey taken at the Networld+InterOp conference in Las Vegas revealed that more than 80 percent of administrators who expect to implement a gigabit network will do so within 12 months.
If everything goes ahead on schedule, network administrators will be able to run their own gigabit networks before the end of 1998. In these days of browser- and push-standard wars, multiple 56-Kbps modem standards, and a bevy of proprietary network specifications, the Gigabit Ethernet standard is a refreshing, if unlikely, development.
