Daniel C. McCarthy, Senior Editor/Special Projects
In today's synchronous digital highway and SONET networks, most switching occurs
electronically. In dense wavelength division multiplexing (DWDM) systems, remote switching still is perceived
largely as a goal. Most current DWDM point-to-point systems rely on manual patching of optical connections to
provision services across the network.
With its TransXpress optical service node, Siemens Information and
Communications Networks Group is hoping to change all of that. The TransXpress supplants manual
patch panels and enables DWDM point-to-point links to be tied into a real optical network. Further,
it allows network managers to manage traffic remotely.
The technology enables Internet service providers -- Siemens' customers --
to drive Internet protocol traffic over an open DWDM platform. At the heart of the TransXpress is an
optical switching subsystem based on microelectromechanical systems (MEMS) from OMM Inc. Siemens software
provides control of the optical switches and links the module to network management.
OMM Inc. raised eyebrows in March when it announced that its optical switching systems had been routing live traffic for more than a month in an unmanned central office in Oakland, Calif. Courtesy of OMM.
Siemens searched for a mature switching technology for its TransXpress node,
said Patrick Leisching, a project manager at Siemens. Not only did OMM have the only off-the-shelf product
available, but its technology had passed Bellcore tests for temperature cycling, vibration and other
standards. More recently, the company raised eyebrows when it announced in March that one of its systems
had been routing live traffic for more than a month in an unmanned central office located in Oakland,
OMM currently supplies 4 X 4 and 8 X 8 optical switch modules. The company plans to include 32 X 32 modules in its portfolio by
the end of the year and eventually deliver 512 X 512 cross-connect configurations.
"We consider 2.5-Gb/s solutions as dead-end solutions," said Hubert Jäger,
business manager for Siemens' Optical Transport Networks. "We supply our customers with future-proof solutions
-- being open to 10 and 40 Gb/s. Just consider a network designed for 2.5 Gb/s and a single customer demanding
the interconnection of two routers, each having 10 Gb/s interfaces. It's not possible. So, future-proof solutions always imply
maximum bit rate."
In addition to increasing the flow of network traffic, Siemens aims to reduce
the stress of network managers. Its TransXpress product integrates a managed optical distribution frame module,
which is a fiber optic distribution frame with a network interface. Jäger said the added element
accelerates the provisioning of services in a DWDM optical network from weeks to minutes. Combined with the automatic switching capability
enabled by OMM's module, applications requiring fast switching -- such as network restoration and
"intelligent" automatic path setup -- can be introduced to DWDM networks.
"All optical cross-connect solutions in the future will require a good
combination of fiber distribution and optical switching just because there will be a crazy large number of optical fibers around to be handled
somehow," said Jäger. "[Managed optical distribution frame/optical cross connects are] the perfect
combination of both technologies already available today."