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¡ôCan Ethernet Be Used WANs?
  Remember the initial hype surrounding ATM? Its proponents dreamed of a world dominated by ATM, the only technology able to stretch across both the LAN and the WAN, creating a single, unifying network delivering voice, video and data over the same wire to desktops everywhere.

Now, rightly or wrongly, some people are dreaming the same dream about Ethernet.

Ethernet, of course, dominates the LAN. It has scored a knockout win over token ring. And it has mounted a successful counterattack against ATM¡¯s advance. First, ATM to the desktop lost favor because Ethernet and Fast Ethernet were already well¡ªentrenched in desktop connections. Then, ATM started losing ground in campus backbones, as Gigabit Ethernet and Lauer 3 switching came to the fore. Now, Gigabit Ethernet for metropolitan and even WANs.

Can Ethernet really pull it off? Can Ethernet make inroads in ATM¡¯s WAN turf?

To be sure, Ethernet has some serious competitors in both MANs and WANs. ATM, for one, remains a potent force. Then there¡¯s a technology proposed by several Swedish companies, called Dynamic synchronous Transfer Mode (DTM). A third competitor is a technology developed by Cisco, called Dynamic Packet Transport (DPT).

But the most well¡ªplaced competitor is Packet over SONET. What Packet over SONET has going for it are built in management capabilities, which are essential for transporting data over very long distance. If something breaks down along the way, there has to be some way of letting the network¡¯s managers know. Ethernet never had to worry about those distance, so it doesn¡¯t have those capabilities.

One possible solution is to create a kind of ¡°digital wrapper¡± around Ethernet frames for long--hual traffic, a wrapper that would have management data akin to SONET. But adding the wrapper might add complexity and expense, which defeats the purpose of using Ethernet technology in the first place.

Much of Ethernet¡¯s success has been based on its low cost and simplicity. Equipment vendors are saying Ethernet in the wide area may have as little as one--fifth the cost of SONET and one¡ªtenth the cost of ATM.

There is enough interest that vendors have been trying to make the next Ethernet standard, 10¡ªGigabit Ethernet, ready for the WAN.

Gigabit Ethernet is already a player in MANs, but whether it can parlay success in that area into success in the WAN is still to be determined. Industry watchers are now saying Ethernet technology will be one option for carriers in the WAN, but not the only one. Plus, it¡¯s not likely to be the dominant one.

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