Multi-degree Reconfigurable Optical Add/Drop Multiplexer (ROADM) functionality extends the flexibility of the CN 4200 to the optical layer

Available for deployment on the CN 4200 RS platform, ROADM allows the same control over the optical path that network operators enjoy over individual services. A ROADM architecture enables networks to maximize available system bandwidth by adding dynamic reconfigurability at the individual wavelength level, ideal for network applications in which wavelength planning is difficult due to uncertain traffic projections. As a result, changes in the network can happen on demand without affecting other wavelengths and services.

CN 4200 ROADM is provided using four key modules:

• Dynamic Wavelength Router (DWR)
• Optical Channel Monitor (OCM-8)
• Variable Gain (Rx) Amplifier (OAV-VS-U-C)
• Fixed Gain (Tx) Amplifier (OAF-BC-B)

The nine-port, Wavelength Selectable Switch (WSS)-based DWR module performs the primary multi-degree optical switching functionality at each ROADM node. Each DWR module contains a WSS capable of dynamically adding, dropping, or expressing any of 44 wavelengths to any of nine ports, in any combination, and can support 10G and 40G wavelengths simultaneously.

The DWR module also incorporates a passive wavelength combiner that can add or multiplex optical signals from up to nine tributary ports into an aggregate signal. Network reconfiguration using the DWR module allows flexible, remote provisioning of any demand, and simplifies network planning by safeguarding upgrade capacity and extending network life—resulting in operational and capital savings and faster revenue capture.

In addition to remotely provisioned add/drop routing, CN 4200 ROADM supports automatic optical power control, which automatically adjusts optical power levels for add/drop and express traffic. To achieve power equalization across all wavelengths, each ROADM node requires one OCM module (OCM-8) to monitor the optical power levels of up to 44 different wavelengths on eight inputs.

The OAV-VS-U-C is a variable gain amplifier typically used as the receiving amplifier to offset fiber loss in the preceding span. The OAV-VS-U-C uses SmartGain™ dynamic gain control, transient suppression and FlexSpan™ auto span loss compensation, and provides mid-stage access for dispersion compensation.

The OAF-BC-B is a booster-combiner amplifier that produces a fixed gain of 20.5 dB on the incoming Dense Wavelength Division Multiplexing (DWDM) signal. The booster acts as an aggregation point for multiple degrees and add/drops, with the capability to support two local add DWR modules. Each OAF-BC-B supports four degrees and is expandable to eight degrees.

Source : www.ciena.com