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A lighthouse as a metaphor

By Scott Bradner

Network World, 09/14/98

Jules Verne's last novel, The Lighthouse at the End of the World, is
about a lighthouse built in 1884 on the island of Isla De Los Estados,
which is just east of Tierra Del Fuego at the southern tip of South

The lighthouse was designed to warn ships trying to cross from the
Atlantic to the Pacific about the dangers posed by the island. The
lighthouse was operated by the Argentine military until rough
conditions on the island forced the lighthouse's abandonment in

Earlier this year, a French navigator who had read the Verne book as
a child completed a reconstruction of the lighthouse in its original
location. It took the navigator more than four years to raise the funds,
and working with a crew of seven, more than two months to finish
construction. On Feb. 26, the lighthouse was donated to the
Argentine Navy, which will operate the lighthouse even though it
serves no current practical value given the prevalence of satellite
navigation systems. Also, because the island is now a sanctuary
where the public is not permitted to land, the lighthouse is only
viewable from the occasional passing ship. The New York Times
report on the lighthouse donation quoted an Argentine Navy captain
about the "symbolic value of the lighthouse," which he said
represented the "dreams of explorers."

What brought this story to mind was a recent Network World article
on ATM flow control (Aug. 31, page 29). The article described ATM
available bit rate (ABR) flow control and included a schematic of a
network complete with ATM to the desktop.

I'm just not sure people should be interested in this topic.

Don't get me wrong. ATM ABR is quite a technical achievement, and
if ATM were a common end-to-end network solution, it could be
quite important. But few observers think ATM will play a significant
role in connecting desktop computers to the rest of the world. The
technology is just too expensive and complex for almost all locations.
The dim prospect for ATM to the desktop is an important factor here
because ATM flow control was designed to function end to end. It is
not at all clear how to use ATM flow control with Ethernet or
token-ring-connected machines.

Clearly ATM is now, and will likely continue to be, an important
technology for WAN services. It could become quite important if the regional phone companies are actually able to deploy inter-local access and transport area ATM services that are distance insensitive. ABR could be of use in these cases if reasonable ways can be developed to transfer the flow control from the WAN to LAN segments. At this point, I am not sure if all the dreams of the technology explorers that have gone into ABR have produced a symbol of technical achievement with no practical value, like Verne's lighthouse, or if ABR will help support useful ATM-based services.

Disclaimer: Harvard has been claiming to have practical value for a rather long time but does not have an opinion on ABR.