6. ATM versus IP to the Desktop

There is a great debate raging among potential service providers as to whether there should be standard IP–10BT connections or ATM connections to their customers' PCs. The two are very similar—the difference is in the specifics of the equipment and not in the amount of equipment required.

There are various advantages to each method of network access:

IP Advantages

• 10BT Ethernet is basically self-learning.
• Inexpensive LAN PC cards already exist.
• 10BT is an industry standard.
• LAN networks are proven and work today.
• There is much expertise in this technology.
• PC software and OS drivers already interface to IP–based LANs.

ATM Advantages

• Streaming video transport has already been proven.
• Mixing of services (e.g., video, telephony, and data) is much easier.
• Traffic speeds conform to standard telephony transport rates (e.g., DS–3, STS–1).
• New PC software and drivers will work with ATM.

The issue actually gets more interesting because both architectures usually interface to an ATM backbone network for high-speed connections over a wide area. Therefore, the real issues are the costs of building the network, the services that are to be carried over it, and the time frame for the implementation. If the need is for data services—Internet connections, work at home, etc., the obvious choice is an IP network. The hardware and software required to implement this network is available and relatively inexpensive.

ATM would be the solution for multiple mixed QoS service requirements in the near future. It is true that the IP technology is being extended to offer tiered QoS with RSVP, and IP telephony is being refined to operate more efficiently. The paradox, however, is that these standards do not exist today. ATM standards are quite complete. However, not all may be easily implementable. In spite of this, there are many ATM networks in existence or currently under construction.

This leaves the issue of costs. The true costs of creating and operating a large-scale data-access network are not known. True, there are portions that are understood, but many others are only projected. This creates great debate over which technology is actually less costly. The only way for the costs to be really known is to build reasonably large networks and compare costs. If one technology is a clear winner—a somewhat doubtful hypothesis—then use that technology. If there is no clear cost advantage, then build the network with the service set that matches the service needs of the potential customers. The issue is to start the implementation phase where the real answers will be determined and subsequently end the interminable discussion phase.

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Last modified Thursday, 03-Aug-2000 10:53:23 CDT
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