Author: Lisa ：lisa@springoptic.com
What Is DWDM?
Dense Wavelength Division Multiplexing (DWDM) is an advanced fiber-optic transmission technology that enables many streams of data to be sent across a single fiber. Each stream resides on its own wavelength, increasing the capacity of the fiber many-fold without installing additional fiber cables.
Deployments of DWDM technology are an essential part of today's long-haul, metro, and data center interconnect (DCI) networks, acting as the glue that makes possible the explosive growth of cloud services, video streaming, and workloads powered by artificial intelligence (AI) technologies.
How DWDM Works
Implementing a DWDM system requires multiplexing a number of wavelengths into one optical signal for transport, then demultiplexing them at the receiving end. Each wavelength is set aside for different, independent data streams-e.g., Ethernet or OTN, Fibre Channel (FC), or SDH/SONET services.
While a full complement of elements make up DWDM systems, those most commonly found in a deployment are:
Transponders or muxponders that do the mapping of client services into wavelengths.
Optical amplifiers that extend the transmission distances over the fibers, potentially for hundreds or thousands of kilometers.
ROADMs (Reconfigurable Optical Add-Drop Multiplexers) that dynamically manage the routing and adding (inserting) and dropping (removing) of wavelengths.
DWDM Network with Mux/Demux and EDFA
Figure 1: Diagram of a DWDM Network with Mux/Demux and EDFA.
Benefits of DWDM Technology
DWDM technology has a number of advantages that have made it the go-to capability in optical networks:
Massive Bandwidth Scalability: The fiber can support up to 96 wavelengths. Each can carry data streams from 10G to 400G+.
Cost Efficiency: DWDM makes use of already laid fiber, not requiring additional cabling and thus saving money.
Protocol Transparency: Many services run over DWDM simultaneously, including Ethernet, OTN, Fibre Channel, and video transport, all riding over a single optical infrastructure.
Ultra-Long-Haul Performance: Optical amplification and forward error correction (FEC) make DWDM suitable to run for long distances with little degradation.
Flexibility: DWDM runs over open line systems, allowing multi-vendor integration and deployment from any vendor.
DWDM Connection Including Transponder, Muxponder, ROADM and Mux/Demux
Figure 2: Example of a DWDM Connection including Transponder, Muxponder, ROADM, and Mux/Demux.
Applications of DWDM Technology
DWDM applications include:
Data Center Interconnect (DCI): Secure links between enterprise and cloud data centers and metro and core networks.
Telecom Carrier Networks: Scaling the core and edge for services like 5G, broadband, and enterprise services.
AI and HPC Workloads: Low latency and high throughput for distributed training and inference via DCI links between data centers.
Enterprise Private Networks: Secure high-capacity and scalable backbones, such as in finance, healthcare, and manufacturing.
Challenges of Deploying DWDM
DWDM is an enormously flexible and difficult technology that requires some degree of optical engineering to ensure quality of signal. Operators must manage optical impairments and maintain monitoring capabilities for service-level assurance. Advanced network management systems and increasing use of automation mitigate potential deployment difficulties.
FAQ: DWDM in Optical Networking
How is DWDM different from CWDM?
CWDM (Coarse Wavelength Division Multiplexing) easily runs a smaller number of sparsely spaced channels for relatively short distances; instead, DWDM uses dozens of closely spaced channels theoretically supporting hundreds and hundreds of wavelengths with the properties of DWDM that allow it to run for long-haul transmission with little degradation over optical fiber.
What services can run over DWDM networks?
Essentially, DWDM is protocol-transparent and can support Ethernet, OTN, Fibre Channel, SONET/SDH, and video services simultaneously over one fiber optic infrastructure.
Is DWDM future-proof?
Yes. DWDM systems are very scalable, supporting wavelengths from 10G to 400G and beyond.
How far can DWDM send data?
With optical amplifiers and dispersion compensation, a DWDM network can send a signal thousands of kilometers with no electrical regeneration; it is perfect for submarine networks and other long-haul/DWDM networks.
Why is DWDM such a big deal in the data center?
Simple-ultra-high capacity and really low latency for thousands of workloads make the technology essential. Also, the capacity and other flexibilities make interconnections and reliability no problem.
