Gigabit Ethernet relieves ATM woes
- By Cheryl Gerber
- Aug 28, 2000
Some users have breathed a resounding sigh of relief when they built Gigabit
Ethernet into their network backbones. Compared with building multiple protocols
on an Asynchronous Transfer Mode (ATM) network, it was a piece of cake.
The main issue with Gigabit Ethernet is not so much the upgrade itself
as the context into which it is upgraded.
Just two years ago, the Army's Information Systems Engineering Command
in Fort Huachuca, Ariz., wrestled with getting an earlier version of Ethernet
to work with its ATM network. The difficulty lay in the fact that ATM does
not understand the popular IP addressing on which Ethernet is based, making
it necessary to use local-area network emulation and addressing conversion
to trick ATM into running with Ethernet LANs.
"Our goal was to move IP packets from point A to B and cut the need
for conversion," said Dan Bradford, director of Fort Huachuca's Technology
Integration Center. "Here's why Gigabit Ethernet is winning: It moves IP
over Ethernet with no new addresses introduced."
This is one of the reasons Fort Huachuca chose Gigabit Ethernet over
IP instead of ATM when it came time to upgrade the network. Also, Ethernet
is an easy choice because it is ubiquitous within the Army. Every workstation
is equipped with an Ethernet network interface card. Plus, Microsoft applications
are IP-aware but not ATM-aware, Bradford noted.
Although ATM has been reliable for the Army, the technology was complex
and expensive, taxing operations and main-tenance. "ATM was a hornet's nest,"
said Bruce Adamson, network administrator at Fort Huachuca. "You just didn't
want to touch it if it was working. By contrast, Gigabit Ethernet has been
simple. The base uses Extreme Networks Inc.'s Summit 48 and Black Diamond
Gigabit Ethernet switches.
"Once we had everything set up and were ready to program the switches,
it took between 30 to 60 minutes to lay down the basic structure in the
Gigabit Ethernet switches," Adamson said. "All the switches have a management
point already on them. It was simply a matter of building the [virtual LANs],
assigning the ports and putting in the IP addresses."
Bradford pointed out yet another difference between ATM and Gigabit
Ethernet — security. "The access control lists of IP addresses you permit
or deny and the security features are more robust on Gigabit Ethernet devices
than on ATM devices," he said.