Good overview of the metro DWDM players:
teledotcom.com
"The venture capital market alone has sunk an estimated $7 billion to $10
billion over the past 18 months into the companies trying to speed
deployment. Cisco Systems Inc. (San Jose, Calif.) dropped nearly $7 billion
worth of its stock this past summer on Cerent Corp. (Petaluma, Calif.), a
startup. And when Sycamore's share price drove from $38 to as high as
$270 on the first day of its initial public offering, many Wall Street analysts
proclaimed the beginning of a wave of optical IPOs (see "Sycamore Takes
Root," page 44).
Established equipment suppliers are also putting forth their particular
solutions. Among them are DWDM powerhouses such as Alcatel N.V.,
Ciena Corp. (Linthicum, Md.), Lucent Technologies Inc., NEC (Tokyo),
Nortel Networks Inc. and Fujitsu Network Communications Inc.
(Richardson, Texas).
For their part, local service providers are content to wait and see, with few
agreeing to discuss their future archi- tectures for this article. Still, between
1998 and 2002, growth in the North American optical networking market is
expected to come more from local than from long-distance networks,
according to research firm Ryan Hankin Kent Inc. (South San Francisco,
Calif.). Growth in local spending will rise from zero to more than 11 percent
of total spending on optical networking, while long-distance growth will slow
from 28 percent to just under 4 percent (see "Small Swells"). The total North
American market is expected to reach $3 billion in 2002."
"There's a lot of talk in the market about so-called "metro DWDM." This
implies replacing Sonet/SDH add/drop multiplexers (ADMs) with
lighter-weight versions of the long-haul DWDM transmission systems and
then somehow mapping protocols, such as the Internet protocol (IP) and
asynchronous transfer mode (ATM), directly to the wavelengths that such
devices produce.
To many, this all-optical approach represents nirvana, the ultimate destination.
But the reality is that it is a strategy of replacement, not evolution, and a
prohibitively expensive one at that.
Current DWDM configurations like this may not be ready to handle the
diverse requirements of metro-area traffic, either. Local networks have much
shorter distances between nodes and a lot more "hop on, hop off" traffic than
long-distance networks. A home for the all-optical approach does exist
today, but it's in point-to-point long-haul and regional networks, say service
provider technologists. Enron Communications Inc. (Portland, Ore.) is one
national network operator deploying its PureIP fiber optic backbone by
linking switch routers directly to its DWDM transmission systems.
For now, most local service providers aren't buying; in fact, many of the new
optical products intended for the local market aren't yet ready for sale. Still,
many carriers are evaluating this remarkably diverse range of options under
development."
" In existing metropolitan fiber optic rings, the spans between nodes are usually
less than 20 kilometers (12.5 miles). These nodes typically consist of
add/drop time-division multiplexers (TDMs), digital cross-connects and
management paraphernalia. DWDM gear, like Sonet/SDH gear, could
possibly be positioned at these nodes, distributing traffic over multiple
wavelengths rather than sending it over a single wavelength in multiple time
slots, as prescribed by today's dominant TDM architectures. This would
increase the existing rings' capacity much the same way that DWDM has
bolstered long-haul segments."
"Time is an issue. The consensus is that it takes six months or more for a
carrier to build out a ring from its central office (CO) when a customer
demands an OC-12 (622 Mbit/s) or higher-speed interface. Thus the push to
apply internetworking principles to wavelengths, which would allow faster,
centralized provisioning and more service flexibility. Others maintain that the
real problem isn't capacity at all but rather getting customers high-speed
access to the already existing fiber."
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