Use ATM for IP messaging, Gigabit Ethernet for everything else

Use ATM for IP messaging, Gigabit Ethernet for everything else

Not long ago, you might have chosen asynchronous transfer mode over Ethernet or Fast Ethernet because it was faster, more scalable and offered a higher quality of service.

Then along came Gigabit Ethernet, with a full array of standards for Category 5 copper wire, quality of service, virtual LAN support and others. You be the judge:

• Gigabit Ethernet brings 10/100/1,000-Mbps scalability across the network'and 10-Gbps Ethernet is just around the corner. ATM offers a range of 155 Mbps to 622 Mbps, and its 25-Mbps rates to the desktop PC can hardly be considered high-speed.

• Gigabit Ethernet is backward-compatible, with legacy Ethernet hardware standards that already are well understood by most network managers and users.

In comparison, ATM isn't easy to work with. Troubleshooting a switched virtual-circuit ATM network with multiple protocols over ATM and its Private Network-to-Network Interface gives even experienced network managers migraines.

• Mapping ATM networks to existing Ethernet topologies is more complicated than extending well-known Ethernet designs across a Gigabit Ethernet backbone. In fact, ATM-Ethernet combinations often require two parallel management systems'one for ATM and the other for the remaining Ethernet LAN devices.

• Gigabit Ethernet technology is driving down the cost of Ethernet and Fast Ethernet and soon will rival Fast Ethernet in price per port. ATM's price per port is higher and will remain higher because of its complexity.

• Neither Gigabit Ethernet nor ATM holds a security edge over the other. Both technologies make use of password protection, user authentication and other physical security measures that don't depend on network protocols.

Do not conclude, however, that ATM has no place in your networking strategy. Circuit-switched ATM is a strong and stable technology that manages IP voice and video messaging particularly well, and it will continue to be useful for specialized applications within government for years to come.

But for most organizations, a conclusion drawn in a recent white paper by Gigabit switch manufacturer Alcatel/Packet Engines will ring true: 'Designing for evolution to Gigabit will be a simpler and quicker strategic move than revolution to ATM.''


'J.B. Miles

inside gcn

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