Data Centre Interconnect Solutions
Connect data centres with engineered optical transport rather than treating the fibre route as a simple point-to-point cable. FDNS delivers Data Centre Interconnect solutions using CWDM, DWDM, dark fibre, active optical platforms and resilient fibre infrastructure, with design review, installation, commissioning, testing and handover.
The service is designed for operators, colocation providers, enterprises, cloud environments, carriers and organisations that need reliable high-capacity connectivity between data centres, disaster-recovery sites, campuses, meet-me rooms, network PoPs or edge facilities.
See our technical guides on Data Centre Interconnect fibre testing and CD/PMD fibre characterisation.
What is Data Centre Interconnect?
Data Centre Interconnect, commonly abbreviated to DCI, is the network infrastructure used to connect two or more data centres so that compute, storage, cloud, backup, replication and network services can operate across separate facilities. The interconnect may use owned dark fibre, leased fibre, wavelength services or carrier circuits, with optical transport selected to suit distance, capacity, fibre availability and resilience requirements.
A DCI design should consider much more than transmission speed. Fibre route diversity, optical loss, connector condition, available wavelengths, dispersion, future capacity, equipment space, power, monitoring, protection strategy and operational handover all affect the reliability of the service. FDNS brings the passive fibre and active optical layers together so the link can be engineered, installed, tested and documented as one controlled solution.
For metro and campus-scale links, passive CWDM can provide a cost-effective way to carry several wavelengths over a single fibre pair where reach and optical budget allow. Where greater channel density, longer reach, higher capacity, amplification or coherent transmission is required, DWDM is normally the more appropriate architecture.
Data Centre Interconnect services
CWDM metro interconnects
FDNS can design and deploy coarse wavelength division multiplexing for short and medium-distance data centre interconnects. Passive CWDM mux and demux units allow multiple optical services to share a fibre pair and can be particularly effective where fibre is scarce but route distances and optical budgets remain within the capability of the chosen optics. We confirm wavelength allocation, insertion loss, connector interfaces, fibre condition and end-to-end link budget before commissioning.
DWDM high-capacity interconnects
Dense wavelength division multiplexing provides significantly greater channel density and is widely used where DCI capacity, reach or scalability exceeds the practical limits of CWDM. FDNS supports active and passive DWDM architectures, including amplified and coherent systems where required by the platform design. Work can include chassis and shelf installation, mux/demux connectivity, patching, optical power verification, wavelength turn-up and coordinated testing with the customer or carrier.
Dark fibre and wavelength services
Where the client has access to dark fibre, FDNS can validate the route and engineer the optical layer around the available fibres. For leased wavelengths or carrier-managed services, we can support the customer-side optical presentation, patching, cross-connects, acceptance testing and fault isolation. The objective is to remove uncertainty at the demarcation point and produce evidence that clearly separates passive fibre, optical transport and Ethernet service performance.
Resilient and diverse DCI
Business-critical DCI normally requires more than one physical route or transmission path. We review A and B path diversity, entry points, meet-me-room separation, carrier handoff, ODF locations and active equipment protection. Where true route diversity is required, the design must confirm that the fibres do not converge onto the same duct, chamber, bridge, building entry or carrier infrastructure further upstream.
Optical platform deployment
FDNS has experience across optical transmission environments including Ciena, ADVA, Transmode/Infinera, PacketLight, Ericsson and legacy Nortel platforms. The exact commissioning scope depends on the vendor, software release, client design and support model. We can support physical installation, fibre presentation, patching, optical verification, service turn-up and structured handover while working alongside the customer, carrier or equipment vendor where software configuration is controlled by another party.
Data centre fibre infrastructure
The DCI service can include ODFs, fibre panels, splice enclosures, OS2 backbone fibre, high-density patching, cross-connects, external routes and building entries. We maintain consistent labelling and port identification from the external fibre through the meet-me room and into the optical transport equipment so test results and operational records can be traced to the correct fibres and wavelengths.
Choosing between CWDM and DWDM
CWDM and DWDM solve different problems. CWDM uses wider wavelength spacing and is often selected for cost-effective metro, campus or inter-building links where a modest number of wavelengths is required and the optical budget is suitable. It can often be deployed with passive mux/demux components and coloured optics, keeping complexity and power consumption relatively low.
DWDM uses much tighter wavelength spacing, supporting far more channels and a broader range of high-capacity transport options. It is generally preferred for higher aggregate bandwidth, longer reach, amplified spans, carrier environments and coherent optical transmission. The correct choice should be based on actual capacity, reach, fibre availability, growth forecast, resilience and lifecycle cost rather than simply selecting the technology with the largest headline capacity.
Capacity and interface planning
DCI requirements can range from multiple 10G and 25G services through 40G, 100G, 400G and 800G transport, depending on the platform and optical design. FDNS reviews client-side interfaces, line-side optics, breakout requirements, transceiver reach, FEC expectations and fibre characteristics so the passive and active layers are compatible. We avoid assuming that a particular Ethernet speed automatically maps to one specific optical architecture.
Coherent optics and long-reach DCI
For high-capacity DCI over longer distances, coherent optics may be used to increase reach and spectral efficiency. These systems can be sensitive to optical power, dispersion, OSNR and platform-specific line engineering. FDNS can support the physical and test requirements around coherent deployment, including fibre characterisation and CD/PMD measurement where the project specification or equipment vendor requires it.
Carrier-neutral and colocation environments
In carrier-neutral data centres the interconnect often crosses several responsibility boundaries. The route may include a customer rack, internal fibre, meet-me room, carrier cross-connect, external fibre and a remote facility. We define and test each boundary so faults can be isolated quickly and handover evidence remains useful after the installation team has left site.
Disaster recovery and business continuity
DCI frequently supports synchronous or asynchronous replication, backup, storage, clustered applications and disaster-recovery services. The physical network must therefore be designed around the required recovery objectives and service criticality. That may mean separate fibre routes, protected optical paths, independent carrier services, diverse building entries or a combination of these controls.
Our Data Centre Interconnect delivery process
The exact delivery model is adapted to the facility, carrier and optical platform. FDNS uses a staged process so route, optics, fibre and testing requirements are agreed before service activation.
1
1. Requirements and topology review
We confirm the sites to be connected, required services, Ethernet speeds, application criticality, fibre ownership, carrier interfaces, resilience targets, preferred optical platform and anticipated future capacity.
2
2. Fibre route and loss-budget assessment
Available fibre routes, connector counts, splice points, patch panels, distance, insertion loss and route diversity are reviewed. Where existing fibre is being reused, test evidence may be required before the final optical design is approved.
3
3. Optical architecture selection
CWDM, DWDM, dark fibre, active transport or a combination is selected against capacity, reach, wavelength count, scalability, resilience and cost. Vendor-specific requirements are incorporated before hardware and optics are committed.
4
4. Installation and cross-connects
ODFs, panels, passive mux/demux units, active optical shelves, patch leads and fibre routes are installed and labelled. Work is coordinated with data-centre access, change control, MOPs, carrier engineers and client operations teams.
5
5
5. Optical commissioning and verification
Connector condition, end-to-end loss, optical power, wavelength presentation and platform alarms are checked. Where required, OTDR, CD/PMD or additional fibre characterisation is completed before service acceptance.
6
6. Ethernet service testing and handover
The completed service can be validated with Ethernet testing appropriate to the handoff, including BERT, FEC observation, RFC 2544 or ITU-T Y.1564/EtherSAM where specified. Native result files, route information, port and wavelength schedules, exceptions and as-built records are assembled for handover.
Testing, fibre characterisation and quality assurance
A DCI can fail even when the fibre appears physically continuous. Contaminated connectors, excessive splice loss, marginal optical power, unexpected reflections, incorrect wavelength presentation or poor route records can create intermittent or difficult-to-diagnose faults. FDNS therefore treats testing as part of the engineered solution rather than a final tick-box exercise.
Depending on the project, testing can include connector end-face inspection, optical loss testing, OTDR at appropriate wavelengths, optical power measurement and fibre characterisation. CD and PMD testing may be required on longer or coherent links where the platform design calls for it. Results are tied to fibre IDs, ODF positions, routes and wavelengths so the client receives evidence that can be used operationally.
For the Ethernet service layer, FDNS can support BERT and service activation methods such as RFC 2544 and ITU-T Y.1564 where appropriate. FEC status, error performance and interface behaviour are considered alongside the optical layer, allowing faults to be separated between fibre, transport and client-side networking.
Where FDNS data centre interconnect solutions are used
FDNS data centre interconnect solutions are used where two or more data centres, carrier hotels, meet-me rooms or technical sites need resilient high-capacity connectivity between them. Typical applications include metro DCI, campus-to-campus links, inter-building fibre, carrier handoffs, business continuity, disaster recovery, cloud connectivity, migration between facilities and high-speed links supporting storage replication, virtualisation and distributed compute.
The correct solution depends on distance, fibre availability, required bandwidth, latency, resilience, wavelength plan and the optical platform being used. FDNS can support dark fibre, CWDM, DWDM and amplified optical transmission environments, helping clients select a practical route from passive fibre through to active optical transport.
Common data centre interconnect risks and how FDNS controls them
DCI failures are often caused by poor fibre condition, excessive loss, contaminated connectors, incorrect wavelength planning, undocumented cross-connects, marginal optical power or insufficient resilience. FDNS reduces these risks through route validation, connector inspection, optical loss testing, OTDR, power measurement and fibre characterisation where required.
For longer or higher-capacity links, CD/PMD, BERT and Ethernet service testing can also be incorporated where the platform or client acceptance criteria require it. By tying test evidence to fibre IDs, ODF ports, wavelengths and route records, FDNS gives operators a traceable baseline for activation, fault finding and future capacity upgrades.
How data centre interconnect differs from our other data centre services
Data centre interconnect focuses on connectivity between facilities rather than the cabling inside a single data hall. Data Centre Cabling Installation manages rack, cabinet and white-space connectivity, while Fibre Optic Data Centre Installation focuses on fibre systems within the facility. FDNS can combine these services where a project requires both internal data centre infrastructure and high-capacity optical links between sites.
Planning a resilient data centre interconnect
A clear interconnect brief should define the sites, optical route, capacity, protection model and commissioning requirements before equipment or fibre paths are committed.
Information needed for a DCI quotation and design
A reliable data centre interconnect starts with a clear definition of the two end sites, the business services that depend on the link and the level of resilience required. FDNS reviews route options, dark fibre or carrier availability, target bandwidth, latency, optical interface type, wavelength requirements, existing fibre condition, diversity objectives and the way the service will enter each facility. This allows the DCI design to be based on the real optical path and operational requirement rather than on headline distance alone.
Where existing information is incomplete, the work package should include route survey, fibre identification, OTDR, attenuation testing or other characterisation before equipment is committed. Early validation is particularly important for CWDM, DWDM, amplified networks and high-speed Ethernet services because small optical or routing issues can become major commissioning problems later.
What should be agreed before the DCI goes live
Provide source and destination sites, route drawings or carrier details, fibre ownership, available core count, required capacity, target service date, resilience model, expected traffic type, optical platform, transceivers, wavelengths, ODF or patching boundaries and any existing test evidence. If the link will use CWDM, DWDM, amplifiers, mux/demux equipment or active transport platforms, identify who owns design, supply, configuration and commissioning responsibilities.
The quotation brief should also define required testing such as optical loss, OTDR, power levels, CD/PMD, BERT, RFC 2544 or Y.1564 where applicable, together with acceptance thresholds, native result files, outage windows, rollback arrangements and handover documentation. This gives FDNS a measurable basis for engineering, pricing and final acceptance.
Why choose FDNS for data centre interconnect solutions?
FDNS combines fibre infrastructure, optical transmission and testing expertise to deliver data centre interconnects as complete engineered services. Our experience includes CWDM, DWDM, amplified optical networks, dark fibre, Ciena and other transmission platforms, optical budgets, OTDR, attenuation, CD/PMD and Ethernet/BERT testing. This means we understand both the physical fibre route and the active optical service riding over it, helping clients build resilient DCI links with clear commissioning and handover evidence.
Optical and Transmission Expertise
CWDM, DWDM, amplified systems, dark fibre, mux/demux arrangements and optical interfaces can be considered together. This helps ensure the selected transmission architecture suits the actual route length, capacity and resilience requirement.
Resilience and Route Diversity
FDNS reviews physical fibre paths, building entries, carrier handoffs and common points of failure so primary and secondary connectivity can be engineered around genuine diversity rather than logical separation alone.
Optical Budget and Fibre Characterisation
Attenuation, OTDR and where required CD/PMD evidence can be used to understand the real fibre path before high-speed optical services are commissioned. This reduces uncertainty around reach and optical margin.
Ethernet and BERT Validation
Where the project requires active service acceptance, Ethernet or BERT testing can be incorporated alongside optical testing. This helps verify not only that light passes through the route, but that the commissioned service performs as intended.
End-to-End DCI Handover
Route records, fibre identifiers, wavelength plans, optical results, active-service results and exceptions can be assembled into a single handover package. This provides operations teams with a clear baseline for service assurance and future capacity upgrades.
Frequently asked questions about data centre interconnect solutions
1. What is Data Centre Interconnect and how does DCI work?
Data Centre Interconnect is the optical and network infrastructure used to connect two or more data centres so they can exchange high volumes of traffic for cloud, storage, replication, backup and application services. DCI can use dark fibre, CWDM, DWDM, carrier wavelengths or active optical transport.
2. Is CWDM suitable for connecting data centres over metro fibre routes?
Yes, where distance, fibre loss, wavelength count and capacity requirements are within the capability of the chosen optics. CWDM is often attractive for metro or campus-scale links because passive mux/demux equipment can place several optical services onto one fibre pair without the complexity of a full DWDM platform.
3. When should a data centre interconnect use DWDM instead of CWDM?
DWDM is generally selected when the network needs more wavelengths, higher aggregate capacity, longer reach, amplification, carrier-grade scalability or coherent optical transmission. The correct choice should be based on an engineered loss and capacity assessment rather than distance alone.
4. Can FDNS test and use existing dark fibre for a DCI service?
Yes. Existing dark fibre can be inspected and tested before the optical design is finalised. We can confirm route condition, optical loss, OTDR events and other characterisation requirements so the client understands whether the fibres are suitable for the intended CWDM, DWDM or direct-optic service.
5. How does FDNS design resilient and physically diverse data centre interconnect paths?
Yes. We can design and deliver A and B interconnect paths where the available infrastructure supports true diversity. This includes reviewing ducts, chambers, building entries, ODFs, carrier routes and active equipment so two services do not appear diverse while sharing a hidden common point of failure.
6. What Ethernet speeds and optical capacities can a data centre interconnect carry?
Capacity depends on the optical platform, transceivers, fibre and reach. DCI commonly carries 10G, 25G, 40G, 100G, 400G and increasingly 800G services. Multiple client interfaces may also be aggregated onto a smaller number of line-side wavelengths depending on the chosen transport system.
7. Can FDNS perform Ethernet, BERT and optical testing on a DCI service?
Yes, where required by the work package. Fibre testing can be combined with Ethernet service testing such as BERT, RFC 2544 or ITU-T Y.1564/EtherSAM. This helps distinguish passive optical faults from transport-platform or client-side Ethernet issues and provides stronger acceptance evidence.
8. Can FDNS support Ciena, ADVA, Infinera and PacketLight optical transmission platforms?
FDNS has experience working around Ciena, ADVA, Transmode/Infinera, PacketLight, Ericsson and other optical transmission environments. The exact commissioning activities depend on the platform, software permissions and support model, but we can support physical installation, fibre presentation, patching, optical verification, turn-up testing and handover alongside the vendor or customer team.
Related data centre services
Design your Data Centre Interconnect with FDNS
Tell us which facilities need to be connected, the required bandwidth, distance, fibre availability, resilience targets and existing optical platforms. FDNS can assess dark fibre, CWDM, DWDM or active optical transport options and define the installation, testing, commissioning and acceptance requirements.