In the past year or so, there’s been quite a lot of fuss over reconfigurable optical add/drop multiplexers (ROADMs), largely because several incumbent carriers appear to be interested in using them to upgrade their Sonet (Synchronous Optical NETwork) and SDH (Synchronous Digital Hierarchy) infrastructures.

As a result, Light Reading has written plenty of articles about requests for proposal (RFPs) for ROADMs and which vendors may be poised to win one of them and possibly notch up contracts worth tens of millions of dollars.

This report aims to put things into context, by explaining what ROADMs are, who makes them, and who makes the optical components used in their manufacture.

It takes the standard form of our “Who Makes What” articles; in other words, we’re providing a first stab at definitions and lists of suppliers and inviting readers to propose additions and modifications.

To start off with, let’s go back to basics. Reconfiguring a dense Wavelength Division Multiplexing (WDM) network can take several weeks if done manually, and with networking requirements constantly changing, that's simply not good enough any more.

The solution could lie with ROADMs, equipment that allows network operators to remotely change which wavelengths are taken in and out of a particular optical switching node.

This technology could save carriers a pile of money by eliminating the dreaded "truck roll" and enabling them to turn on revenue generating services much faster.

The market for ROADM technology could be about to take off. In a recent study of 27 major telecom carriers, Infonetics Research Inc. found the majority of them (26 out of the 27) intend to deploy ROADM technology in the future. Some 25 percent of carriers in the study said they plan to deploy ROADM technology within the next 12 months.

The market for "systems sold with ROADM capability" is estimated to be worth around $85 million in 2004, according to Michael Howard, president of Infonetics, and principle author of the study.

Backing up Infonetics' findings, there are several prominent contracts up for grabs at the moment, including RFPs from AT&T Corp. (NYSE: T), SBC Communications Inc. (NYSE: SBC), and Verizon Communications Inc. (NYSE: VZ).

There has also been a spate of ROADM product announcements, including new products from Cisco Systems Inc. (Nasdaq: CSCO).

"Every man and his dog is going to have a ROADM story soon," moans Rob Lane, VP of marketing and business development at ROADM startup Tropic Networks Inc. "Now that service providers have demonstrated that ROADM is real, everyone's rushing to catch up."

That's where this report comes in. It aims to help folk keep track of a rapidly developing market, by identifying all the manufacturers of ROADM equipment, as well as those that supply the enabling component technologies, such as wavelength blockers and tunable filters.

Click on the hyperlinks to go directly to the section of interest:

Your input

As with other Light Reading "Who Makes What" taxonomies already published (see Who Makes What: Optical Components 2004), this is just a starting point. We now need you to dive in and suggest additions, corrections, and revisions to this report, which is a living document. We'll update it regularly to reflect your input.

To make suggestions, we'd prefer you use the message board, so that everyone can participate in discussions. However, if you prefer to keep your communications private, please send them to [email protected] and include "Who Makes What" and your company name in the subject field.

Feel free to go beyond pointing to company names we may have mistakenly omitted. We're also interested in suggestions for further product categories and refinements to the category structure.

— Pauline Rigby, Senior Editor, Light Reading

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There are two key architectures for ROADMs:

Broadcast and Select

This particular way of designing ROADMs has proved popular, with early products from Marconi, Ciena, and others being based on it.

How does it work? In the diagram above, light coming in on the left is divided equally between two paths by a splitter. The lower path is for the drop channels, which are selected by, for example, tunable filters. In the other path, channels that have already been dropped are eliminated from the output of the switch by blocking them with a component called a wavelength blocker (denoted WB). Finally, channels are added at the output using another coupler. For complete reconfigurability, the add channels may come from tunable lasers.

One reason this architecture has attracted vendors is that it has a lower insertion loss than ROADMs based on switch fabrics such as MEMS (micro-electro-mechanical switches). This seems to be as much due to the high losses inherent in other technologies as anything else, and it could change if other switching technologies improve.

A second reason may be that it can offer a lower component count than alternatives, which helps keep costs down.

Demux, Switch, Mux

A more traditional ROADM architecture is based on multiplexers and switching fabrics. All the incoming wavelengths must be demultiplexed, then switched to the appropriate outputs and recombined. The functionality is the same as a plain vanilla optical switch, but with a few extras on the network management side.

Vendors of the components that are key to ROADMs, such as switching fabrics, wavelength blockers, and tunable filters, are listed on pages 4 and 5. For other components such as tunable lasers, which can be incorporated into ROADMs, please see the Light Reading report – Who Makes What: Optical Components 2004.

Alcatel SA (NYSE: ALA; Paris: CGEP:PA)

Product Name: Related stories on Light Reading:

Ciena Corp. (Nasdaq: CIEN)

Product Name: Corestream Agility

Product Info: http://www.ciena.com/products/corestream/soadm.htmRelated stories on Light Reading:

Cisco Systems Inc. (Nasdaq: CSCO)

Product Name: ONS 15454 Multiservice Transport Platform

Product Info: http://www.cisco.com/en/US/products/hw/optical/ps2006/ps5320/Cisco introduced a ROADM feature to its ONS 15454 system at the Supercomm show this June. Cisco's ROADM controls 32 wavelengths, allowing adding or dropping in any permutation. It comes in two parts: a double-width card for the wavelength-selective switch – the element that blocks wavelengths – and a single-card demultiplexer. The technology isn't home grown, reportedly, but Cisco isn't saying who the development partner is.

Related stories on Light Reading:

Fujitsu Network Communications Inc. (FNC)

Product name: Flashwave 7500

Product Info: http://www.fujitsu.com/us/services/Telecom/ByCateg/RegNMetroCore/BE8E8pAX7A.html

Fujitsu has released several ROADM products: It has recently unveiled an extension to its Flashwave 7500 DWDM system that bestows ROADM capability on it.Fujitsu is currently offering a thin film filter-based OADM as part of its metro DWDM product range, but says that it has only "limited deployment."

Mahi Networks Inc.

Product Name: Vx7 Multi-Service Core Transport System

Product Info: http://www.mahinetworks.com/products/vx7/index.shtmlMahi acquired its ROADM technology by buying the assets of Photuris.

Related stories on Light Reading:

Marconi Corp. plc (Nasdaq: MRCIY; London: MONI)

Product Names: PMA32 and Multihaul 3000

Product Info: