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WDM Network Inventory – 5 Advantages to Answer: Why WDM

7 February 2023
Mike Dorland

Trusted by:

Telecom Egypt
BC Hydro


National Grid
Open Fiber
TPX Communications
Ella Link
Red Iris
Surf Net

Optical transport networks and wavelength division multiplexer technology are here to stay so managing WDM network inventory is a challenge that operators must address without delay.

As demand for broadband and by extension Optical Transport Networks surges, the global wavelength division multiplexer (WDM) market has boomed – and that means the question of managing WDM network inventory is one that needs to be tackled now. Valued at $3.56 billion in 2019, according to Allied Market Research the WDM market is projected to reach $5.61 billion by 2027, registering a CAGR of 6.4% from 2020 to 2027 so there’s no time to delay.

To remind ourselves what we’re talking about first, WDM is a fibre-optic transmission mechanism that uses multiple light wavelengths to send data over the same medium. The optical outputs from multiple lasers (operating at different wavelengths) are combined and transported over a single fibre, all while maintaining complete separation of data streams. WDM enables communication in both directions of a fibre cable, vital as demand for bandwidth and internet usage increases exponentially.  

Why WDM? 5 advantages

More specifically, WDM’s market drivers (which in turn are driving the need for WDM network inventory to be managed) can be listed as follows:

  1. WDM systems can transmit and receive data used for extreme bandwidth activity such as 100G, 400G, and higher.
  2. WDM can connect new channels without disrupting pre-existing traffic meaning it’s a suitable tool for rapid and easy network expansion.
  3. It delivers transmission transparency since wavelengths (of light) are independent of each other.
  4. It’s an extremely reliable system, so satisfies performance requirements.
  5. By enabling the network operator to maximize fibre utilization, it also optimizes overall network investment.

It’s also worth remembering that WDM comes in two varieties – which further expands the BoM that makes up WDM network inventory.

These include: 

  • CWDM (coarse wavelength division multiplexing), which refers to the spacing between channels (generally 20 nanometres apart) and
  • DWDM (dense wavelength division multiplexing) which increases the bandwidth of a single fibre without the required spacing. 

CWDM allows up to 18 channels to be connected over fibre optics with a wavelength ranging down to 1270 nm. DWDM, meanwhile, utilizes up to 80 channels carrying data at 2.5 Gbps.

network inventory vc4

WDM and network inventory: a challenge

As with any network technology, this extends the elements that are part of the overall inventory, so WDM presents a familiar challenge. It brings new components into play, new assets that need to be managed by the operator. The inevitable consequence of this is that telecom network asset management in general becomes more complicated – a challenge that must be met if the operator is to continue to deliver ever more agile operations and services via OTN and WDM. 

As a result, operators need to properly understand their WDM assets to effectively meet a number of core business needs. These include operational performance as well as planning for activating unlit fibres and for building out new links. 

But what are the WDM assets in question? What’s new for network inventory? Principally, a WDM system consists of four main elements as follows:


In a WDM system transceivers are wavelength-specific lasers whose function is to convert data signals from IP switches to optical signals before transmission over the network. Any type of data (voice or video) can be transported simultaneously over a fibre in this manner.

Multiplexers (and demultiplexers)

Multiplexers (and demultiplexers) are responsible for optimizing the use of fibre channels. Multiplexers collect the data and transmit it over the network. De-multiplexers separate data into different channels. 

Patch cables

These are used to join transceivers and multiplexers. One common form is the LC connector, which connects transceiver output to multiplexer input.

Dark fibre networks

All WDM systems must have access to a dark fibre network as, once lit, these become the physical means of transporting the optical traffic. One fibre is used for data transmission, while the other is used for data retrieval.  

Managing WDM network inventory

With those assets deployed, to manage the expanded network inventory (driven by WDM) the operator must ensure that the entire network is visible to its operational systems. 

As we’ve already said, this presents challenges at the best of times and with WDM, it’s pressing given the rate at bandwidth requirements are growing. As a result, effective Network Inventory Management is central to WDM’s success because:

  • Network management capabilities must be improved to leverage WDM. Issues such as performance management, fault management, configuration management, and restoration management are all critical if network manageability and interoperability are to be realised. For instance, networks must be simple to configure as most operators don’t have the time or resources to reconfigure a ring each time a new optical device is added.  Integrated network inventory management in this regard is a vital function.
  • Integration of WDM assets is critical to the successful aggregation of the multiple services that operators want to deliver. If integration isn’t realised, the network becomes difficult to manage and the benefits of WDM are unlikely to be unlocked.
  • Operators must be able to both view and manage the relationship between the different elements that support the individual wavelengths over which data is transported. A continual awareness of the fibres themselves, fibre locations, all aspects of service delivery, description of services, customer identity and status, is necessary to achieve this.
  • Optical network evolution isn’t static. As the network evolves, new assets, iterations, and services must be continually (and precisely) re-aligned. Operators have to remain on top of both inventory and processes to ensure their networks meet customer demands. 

VC4-IMS: unlocking the advantages of WDM

Network Inventory Management systems are a foundational aspect of the successful development and operation of Optical Transport Networks and, by extension, WDM network inventory presents a critical challenge that must be met.

If you’d like to discuss WDM network inventory management and how you can meet the challenges they post, we’d be happy to talk further and at the same time provide a brief demo of VC4-IMS, the market leading solution to the challenges we’ve just discussed.  

This will show you how to bring clarity to your own assets and provide you with a foundation for ensuring that your investments in agile network evolution deliver the network performance and results that you’re targeting.