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Technology Stocks : George Gilder - Forbes ASAP -- Ignore unavailable to you. Want to Upgrade?

To: Asterisk who wrote (739)	10/21/1998 11:49:00 AM
From: Beltropolis Boy	Respond to of 5853

Hate to be a techno ninny but what are WDM and DWDM? michael. DWDM is Dense Wave Division Multiplexing. while i'm by no means an authority on the topic, to give you some background, the original networks built did not factor in the amount of traffic generated by internet access (doubling ~4 months), faxes, multiple phone lines, modems, teleconferencing, data/video transmission, etc. basically, we're now faced with multi-faceted challenges of increased service needs, fiber exhaust, and bandwidth management; hence, service providers need options to provide an economical solution. one way to alleviate fiber exhaust is to lay more fiber, however, this is obviously a lengthy process and generally cost-prohibitive. additionally, laying new fiber will not necessarily enable the service provider to offer new services. frankly, laying new cable is very expensive and carriers would much rather get greater efficiency out of the fiber already in the ground. to wit, DWDM — a technology that combines multiple optical signals so that they can be amplified as a group and transported over a single fiber to increase capacity. DWDM ‘boxes' sit at either end of the fiber-optic cable and boost bandwidth — the amount of information that can cross a network — by sending multiple light waves (or channels) through one optical fiber. essentially, DWDM increases the capacity of embedded fiber by first assigning incoming optical signals to specific frequencies within a designated frequency band and then multiplexing the resulting signals out onto one fiber. because incoming signals are never terminated in the optical layer, the interface can be bit-rate and format independent, allowing the service provider to integrate the DWDM technology easily with existing equipment in the network (e.g., routers and switches) while gaining access to the untapped capacity in the embedded fiber. with DWDM pushing 96+ channels, when mr. gilder dropped the prefix "D," he was simply making an analogy to how we'll eventually just refer to it as WDM. à la when where-are-you-now "mc hammer" recoined himself "hammer." yeah, i'm scared that i know that too. hope this helps, -chris.

To: Asterisk who wrote (739)	10/23/1998 12:46:00 PM
From: George Gilder	Read Replies (2) \| Respond to of 5853

WDM is wavelength division multiplexing--sending many bitstreams on different colors of light (actually infrared), down a single strand of fiber. This hugely increases the possible capacity of the fiber. It also hugely increases flexibility, by allowing cheap add-drop functions. You can take a bitstream off a backbone by passive optical filtering of wavelengths (called lambdas) rather than by megadollar processing of all the contents of the pipe (in order to tap one desired bitstream, as SONET requires). DWDM is a ridiculous acronym that noone should use. It means "dense" WDM and is normally invoked by companies that have less dense systems than the state of the art, which is at least 16 lambdas, heading for 120 at Ciena. It is a stupid marketing term.