ROADM spurs DWDM scalability

New applications, government regulations and the migration of traditional business functions to e-business models are driving deployment of dense wavelength division multiplexing networks as a cost-effective, scalable solution for high-bandwidth needs. But early adopters of enterprise DWDM networks have found scalability falls short of their demands because of the onerous redesign required to upgrade DWDM networks.

Reconfigurable DWDM networking, based on reconfigurable optical add/drop multiplexers (ROADM), eliminates the growing pains associated with legacy DWDM networking techniques. ROADMs provide an automated mechanism to flexibly add capacity as it's needed without resorting to expensive, service-interrupting forklift upgrades.

ROADMs give network administrators the ability to select via software which of 32 DWDM channels to add, drop or pass-through at each site in a DWDM network. This lets them seamlessly add services as end-user demand necessitates.

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New applications, government regulations and the migration of traditional business functions to e-business models are driving deployment of dense wavelength division multiplexing networks as a cost-effective, scalable solution for high-bandwidth needs. But early adopters of enterprise DWDM networks have found scalability falls short of their demands because of the onerous redesign required to upgrade DWDM networks.

Reconfigurable DWDM networking, based on reconfigurable optical add/drop multiplexers (ROADM), eliminates the growing pains associated with legacy DWDM networking techniques. ROADMs provide an automated mechanism to flexibly add capacity as it's needed without resorting to expensive, service-interrupting forklift upgrades.

ROADMs give network administrators the ability to select via software which of 32 DWDM channels to add, drop or pass-through at each site in a DWDM network. This lets them seamlessly add services as end-user demand necessitates.

ROADM functionality comprises two elements, wavelength selection and de-multiplexing. The roles of wavelength selection and de-multiplexing are performed by their their respective physical components: wavelength selector switch (WSS) and de-multiplexer (DMX). The WSS provides the software selectable wavelength function, whereby users choose which wavelength or group of wavelengths to add/drop at a particular ROADM site on a network. On the "drop" path, the DMX de-multiplexes the group of wavelengths dropped by the WSS into individual channels that subsequently drive the receive inputs of collocated client devices such as Ethernet switches and Fibre Channel switches. Hence, WSS/DMX components combine to provide the necessary capability to add or drop any of 32 wavelengths from the composite DWDM line signal to/from client devices.

The significant difference between the function provided by the ROADM configuration and a simple 32-channel multiplexer/demultiplexer (that is, a terminal filter used in legacy DWDM networks) is the ability to block or pass-through any combination of the 32 DWDM wavelengths, providing network administrators with unlimited flexibility at every ROADM node in a DWDM net.

The primary benefit of an enterprise ROADM network is its ability to add capacity wherever and whenever it is required, with the assurance that the underlying network automatically will compensate for the added traffic, eliminating the need for manual tuning or wholesale upgrades.

In a ROADM network, only those points in the network that require additional services are touched. Once a transponder or muxponder is installed to transmit or receive the new wavelength between customer premises equipment at endpoint locations, a network administrator connects the two points via provisioning software and the ROADM network adds/drops the appropriate wavelength at the new locations. No new equipment is required, traffic is not interrupted and service technicians do not need to be dispatched to intermediate locations to manually compensate for the added traffic load.