OM4 Fibre Optic Cabling for Next-Generation Data Centres

OM4 Fibre Optic Cabling provides the bandwidth, transmission performance and deployment flexibility required by modern data centres. As public cloud platforms, artificial intelligence, virtualisation and data-intensive applications expand, data centres must carry more traffic at progressively higher speeds.

Consequently, network designers need fibre infrastructure that supports current applications while providing a practical migration path towards faster technologies. OM4 multimode fibre helps meet this requirement by delivering higher bandwidth and longer transmission distances than earlier multimode fibre categories.

Moreover, OM4 retains the commercial advantages associated with short-reach multimode optical transceivers. Therefore, it remains an important cabling option for enterprise, cloud, colocation and high-performance computing environments.

However, OM4 does not suit every data centre connection. Designers must evaluate the transmission speed, channel length, transceiver type, fibre count, cable construction and future migration strategy before selecting it.

What Is OM4 Fibre Optic Cabling?

OM4 Fibre Optic Cabling uses laser-optimised, 50-micron graded-index multimode optical fibre. Manufacturers design it primarily for high-speed transmission using 850-nanometre optical sources.

Like OM2 and OM3, OM4 has a nominal 50-micron core. However, core diameter alone does not determine optical performance. Instead, OM4 achieves higher bandwidth because manufacturers control the fibre’s refractive-index profile more precisely.

As light travels through multimode fibre, different light paths can arrive at slightly different times. Engineers call this effect differential mode delay. If these timing differences become too large, the receiver can no longer distinguish individual data signals accurately.

Therefore, OM4 manufacturers optimise the fibre to reduce differential mode delay. As a result, OM4 can support higher data rates or longer transmission distances than earlier multimode fibres.

OM4 typically provides an effective modal bandwidth of:

• 4,700 MHz·km at 850 nm
• 500 MHz·km at 1,300 nm

By comparison, OM3 provides an effective modal bandwidth of at least 2,000 MHz·km at 850 nm. Consequently, OM4 gives network designers more performance margin for many short-reach data centre applications.

How Does OM4 Differ from OM1, OM2 and OM3?

Multimode fibre categories share several characteristics. Nevertheless, they do not provide the same bandwidth, transmission distance or migration capability.

Fibre category	Core diameter	Typical optical source	Effective modal bandwidth at 850 nm	Current position
OM1	62.5 microns	LED	Not normally specified for modern laser applications	Legacy
OM2	50 microns	LED	Not normally specified for modern laser applications	Legacy
OM3	50 microns	850 nm laser	2,000 MHz·km	Current
OM4	50 microns	850 nm laser	4,700 MHz·km	Current/high performance
OM5	50 microns	Multiple short wavelengths	4,700 MHz·km at 850 nm	Specialised applications

OM1 and OM2 supported earlier enterprise networks effectively. However, their limited bandwidth makes them unsuitable for most new high-speed data centre backbones.

OM3 represented a significant improvement because manufacturers optimised it for vertical-cavity surface-emitting lasers, commonly known as VCSELs. Therefore, OM3 enabled substantially faster transmission than OM1 and OM2.

OM4 builds on the same laser-optimised technology. However, it provides more than twice the effective modal bandwidth of OM3 at 850 nm.

As a result, OM4 often supports a longer transmission distance for the same Ethernet application. Alternatively, it can provide additional optical performance margin within a shorter channel.

OM4 Fibre Optic Cabling and Industry Standards

Industry standards define the optical and mechanical characteristics that allow cabling and network equipment from different manufacturers to operate together.

The Telecommunications Industry Association originally defined OM4 through ANSI/TIA-492AAAD. That specification played an important role in developing high-speed multimode fibre systems.

However, the standards framework has since changed. In 2024, TIA published ANSI/TIA-492AAAF-A. This document adopts IEC 60793-2-10:2022 with modifications and covers Class 1a graded-index multimode optical fibres.

Importantly, the newer document replaced several earlier individual TIA fibre specifications, including ANSI/TIA-492AAAD. Therefore, designers should not treat 492AAAD as a new or proposed specification.

You can review the announcement through the Telecommunications Industry Association.

Other standards that influence OM4 data centre cabling include:

• ISO/IEC 11801 for generic customer-premises cabling
• ANSI/TIA-568 structured cabling standards
• ANSI/TIA-942 data centre telecommunications infrastructure
• IEEE 802.3 Ethernet standards
• Fibre Channel standards developed through INCITS T11

These standards address different parts of the network. For example, fibre specifications define the transmission medium. In contrast, IEEE Ethernet standards define optical interfaces, lane configurations and supported channel lengths.

Consequently, designers should never determine OM4 transmission distance from the fibre category alone. Instead, they must confirm the selected Ethernet or Fibre Channel interface.

What Network Speeds Can OM4 Support?

OM4 Fibre Optic Cabling supports a wide range of Ethernet and Fibre Channel applications. However, the supported distance changes according to the optical interface, transceiver design and applicable standard.

Common Ethernet examples include:

Ethernet application	Typical maximum OM4 channel length*
10GBASE-SR	400 metres
25GBASE-SR	100 metres
40GBASE-SR4	150 metres
100GBASE-SR4	100 metres
100GBASE-SR1	100 metres
200GBASE-SR2	100 metres
400GBASE-SR4	100 metres

*Always confirm the equipment manufacturer’s specifications, connector losses, channel topology and applicable IEEE standard before finalising the design.

Earlier 100 Gigabit Ethernet implementations used more optical lanes than many current systems. However, newer transceivers achieve higher data rates per lane. Consequently, manufacturers can now deliver greater total capacity while using fewer optical lanes.

Therefore, a general statement such as “OM4 supports 100 Gbit/sec over 150 metres” can mislead readers. Some earlier optical implementations offered that reach, while commonly specified 100G interfaces often support 100 metres over OM4.

Moreover, two transceivers that operate at the same total data rate may use different optical lane configurations. As a result, they may require different fibre counts and support different distances.

Before specifying the cabling, designers should confirm:

• The Ethernet or Fibre Channel standard
• The exact transceiver type
• The number of optical lanes
• The required fibre count
• The maximum channel length
• The number of connection points
• The permitted channel insertion loss

Why OM4 Remains Relevant in Modern Data Centres

Data centre operators now deploy 100G, 200G, 400G and faster Ethernet systems. At first glance, this growth may suggest that OS2 singlemode fibre should replace multimode fibre entirely.

In practice, however, both fibre types continue to serve important roles.

OM4 remains relevant because many server, storage and switch connections operate over relatively short distances. Therefore, data centre operators can often use multimode transceivers without sacrificing the required network performance.

Cost-Effective Short-Reach Connectivity

Multimode optical modules often cost less than comparable singlemode modules for short-reach applications. Consequently, large data centres may achieve meaningful savings when they deploy hundreds or thousands of optical links.

However, the cable represents only one part of the total system cost. Designers must also consider:

• Optical transceivers
• Switch and server interfaces
• Fibre enclosures
• Installation labour
• Testing and commissioning
• Replacement equipment
• Future network upgrades
• Energy consumption

Therefore, the most economical fibre type depends on the complete network architecture rather than the cable price alone.

High Bandwidth Across Data Centre Distances

Many data centre connections cover less than 100 metres. As a result, OM4 supports numerous high-speed optical interfaces across typical data hall distances.

For example, designers may use OM4 for switch-to-switch, server-to-switch and storage network connections. Furthermore, OM4 can support high-performance computing clusters where large volumes of information must move between equipment quickly.

OM4 can also provide greater design margin than OM3. This additional margin becomes particularly valuable when a channel approaches its maximum permitted distance or contains several connection points.

Faster Deployment with Factory-Tested Cabling

Data centres require repeatable performance and predictable commissioning. For this reason, many operators use Pre Terminated Fibre Optic Cable rather than terminating every fibre in the field.

Manufacturers install and test the connectors in a controlled factory environment. Consequently, installers can reduce on-site labour, improve connector consistency and accelerate deployment.

Furthermore, factory testing provides documented performance before the cable reaches the project. Therefore, data centre operators can reduce uncertainty during commissioning.

Easier Expansion and Reconfiguration

Cloud and colocation facilities often expand in stages. Consequently, operators need infrastructure that they can install, test and activate quickly.

A carefully specified OM4 pre terminated fibre optic cable can simplify equipment-row extensions, switch upgrades and capacity expansions.

Additionally, factory-terminated assemblies reduce the amount of specialist termination work required inside operational data halls. As a result, project teams can complete upgrades with less disruption to existing infrastructure.

OM4 Versus Singlemode Fibre

Neither OM4 nor OS2 singlemode fibre provides the best answer for every data centre connection.

OM4 generally suits short-reach applications where multimode transceiver economics, high bandwidth and fast deployment matter. In contrast, OS2 suits longer links and networks that require maximum migration flexibility.

Design factor	OM4 multimode fibre	OS2 singlemode fibre
Core diameter	50 microns	Approximately 9 microns
Common wavelength	850 nm	1,310 or 1,550 nm
Typical data centre role	Short-reach equipment connections	Backbone and longer-reach connections
Distance capability	Application-dependent; commonly 100–400 metres	Kilometres, depending on the interface
Transceiver cost	Often lower for short-reach links	Often higher, although pricing continues to change
Long-term distance flexibility	Moderate	Excellent
Best suited to	Defined short-reach architectures	Long-distance and highly scalable backbones

Singlemode passive cable does not automatically cost more than multimode cable. In fact, cable prices can sometimes remain relatively close.

However, active optical equipment often creates the largest commercial difference. Historically, singlemode transceivers cost substantially more than short-reach multimode transceivers.

Nevertheless, singlemode transceiver prices continue to change. Therefore, designers should compare current equipment pricing rather than rely on historical assumptions.

OM4 may offer the stronger choice when:

• Channel lengths remain within the supported OM4 distance
• Short-reach multimode transceivers provide a cost advantage
• The network architecture remains stable and predictable
• The installation requires high bandwidth across a data hall
• Rapid deployment remains an important project objective

Conversely, OS2 may offer the stronger choice when:

• Links extend between buildings
• Channel distances may increase
• The future equipment architecture remains uncertain
• The network requires maximum wavelength flexibility
• Future applications may exceed OM4 distance limits

Where Does OM4 Fit Within a Data Centre?

OM4 works particularly well where network teams can define channel lengths and equipment architecture accurately.

Typical OM4 applications include:

• Connections between servers and top-of-rack switches
• Equipment distribution area links
• Leaf-and-spine switch connections
• Storage area networks
• High-performance computing clusters
• Short-reach data hall interconnections
• Fibre Channel connections
• Cloud and virtualisation infrastructure
• Network equipment upgrades
• Edge data centre infrastructure

However, OS2 may provide a better choice for campus backbones, inter-building links, carrier connections and longer data centre interconnects.

Therefore, many facilities adopt a mixed-fibre strategy. They use OM4 inside data halls while using OS2 for longer backbone and external connections.

This approach allows the organisation to match each fibre type to the application. Moreover, it avoids paying for long-distance capability where the network does not require it.

Choosing the Right OM4 Cable Construction

Selecting OM4 fibre represents only one part of the specification. The cable construction must also suit the route, installation method and operating environment.

Indoor Tight-Buffered Cable

Tight-buffered OM4 cable suits many indoor equipment-room, riser and backbone pathways. Its construction allows technicians to identify and handle individual fibres easily.

Additionally, tight-buffered cable can simplify direct termination and enclosure management. However, designers must still specify the appropriate fire-performance classification for the installation environment.

Indoor/Outdoor Cable

Indoor/outdoor cable can reduce the number of transition points between external pathways and internal communications spaces.

Therefore, it may simplify backbone installations that pass through several environmental zones. Furthermore, fewer transition points can reduce the number of splices, enclosures and potential failure locations.

Loose Tube Cable

Loose tube cable protects optical fibres inside buffer tubes and allows the fibres to move independently of the outer cable structure. Consequently, it can provide strong environmental and mechanical protection for outdoor pathways.

Manufacturers may use gel-filled or dry water-blocking technologies within the cable. However, dry water-blocking designs often simplify installation, preparation and worksite clean-up.

Where a data centre requires compact outdoor backbone cabling, the Mini Loose Tube Fibre Optic Cable Authority Hub explains the construction, protection and specification factors in greater detail.

Pre-Terminated OM4 Cable Assemblies

Pre-terminated assemblies combine the selected cable construction with factory-installed connectors, defined breakout lengths and factory testing.

As a result, installers can route and connect the cable without completing every termination on site. Moreover, manufacturers can configure the assembly to match the required equipment interfaces, enclosures and installation pathway.

A correctly designed Pre Terminated Fibre Optic Cable can therefore reduce installation time while improving commissioning consistency across repeatable data centre links.

OM4 in Outdoor and Inter-Building Data Centre Networks

Not every data centre fibre route remains inside a controlled building environment.

For example, data centre campuses, modular facilities and edge networks may require fibre between separate buildings, external equipment compounds or remote communications rooms.

In these environments, optical performance alone does not determine cable suitability. Designers must also consider:

• Moisture exposure
• Conduit capacity
• Cable diameter
• Maximum pulling tension
• Crush resistance
• Minimum bend radius
• Rodent or termite risk
• UV exposure
• Jacket material
• Water-blocking construction
• Temperature range

Compact OM4 Mini Loose Tube Fibre Optic Cable can provide a practical option for outdoor conduit and duct networks where pathway space remains limited.

Furthermore, a smaller cable diameter can improve conduit utilisation and simplify installation. Nevertheless, designers must still confirm tensile strength, crush resistance, water blocking and environmental performance before specifying the cable.

For demanding Australian installations, the RapidConnect TR-Series Mini Loose Tube Fibre Optic Cable provides a specialised platform for compact outdoor fibre networks.

OM4 Fibre Optic Patch Leads for Data Centres

OM4 fibre optic patch leads provide removable connections between compatible multimode transceivers, network switches, servers, storage equipment and fibre patch panels. Therefore, they form an important part of the complete data-centre optical channel. RapidConnect Fibre Optic Patch Leads are available with Erika Violet RAL 4003 OM4 cable, factory-terminated connectors and LSZH jackets. In addition, every assembly undergoes optical testing and includes individual test results. However, designers must still confirm the transmission standard, channel length, connector interfaces and complete optical-loss budget before selecting an OM4 patch lead.

Important OM4 Design Considerations

A successful OM4 installation requires more than choosing the correct fibre category.

Confirm the Transmission Standard

First, identify the Ethernet or Fibre Channel interface that the active equipment will use. Then, confirm the maximum supported OM4 channel length for that specific interface.

Additionally, check the transceiver manufacturer’s data because equipment performance can vary between products.

Calculate the Complete Optical Loss Budget

Connectors, splices and other passive components introduce optical loss. Therefore, designers should calculate the complete channel loss rather than assess cable length in isolation.

Moreover, the design should include a reasonable operating margin. This margin can accommodate minor contamination, ageing and future connection changes without pushing the channel beyond its permitted loss budget.

Plan for Future Network Speeds

A cable that supports the current application may not support the next application over the same distance.

Consequently, designers should model likely equipment upgrades before installing permanent backbone infrastructure. For example, an OM4 channel may support 10G over 400 metres but support a future 100G interface over only 100 metres.

Therefore, the migration path matters as much as the current data rate.

Confirm the Required Fibre Count

Different optical interfaces use different numbers of fibres. As a result, designers must confirm the future transceiver architecture before determining the permanent fibre count.

Furthermore, installing spare fibres during the initial project usually costs less than installing another cable later. Therefore, the design should include capacity for maintenance, redundancy and future expansion.

Control Connector Cleanliness

Connector contamination can cause insertion loss, reflectance and unstable network performance.

Therefore, installers should inspect, clean and re-inspect every connector before mating it. Additionally, they should keep dust caps in place until immediately before connection.

Protect Bend Radius and Pulling Tension

Excessive bending or pulling can damage the cable and affect optical performance.

Consequently, installers must follow the cable manufacturer’s minimum bend-radius and maximum pulling-tension requirements. They should also use suitable pulling equipment and cable-management hardware throughout the installation.

Test and Document Every Link

Commissioning should include polarity verification, connector inspection and insertion-loss testing.

Additionally, longer or more complex backbone routes may require OTDR testing. Once testing finishes, the organisation should retain the results as part of the network’s permanent asset records.

Is OM4 Fibre Optic Cabling Future-Proof?

No fibre type provides unlimited future-proofing. Instead, OM4 offers a defined performance platform that supports several generations of short-reach Ethernet and Fibre Channel equipment.

OM4 makes sense when:

• Channel lengths fall within the relevant application limits
• Multimode transceivers provide a commercial advantage
• The network requires high bandwidth over short distances
• Designers understand the likely migration path
• Fast and repeatable deployment matters
• The data centre uses predictable channel configurations

However, OS2 may provide a better long-term choice when:

• Link distances may increase
• Equipment architecture remains uncertain
• The network must support campus or inter-building routes
• Designers require maximum wavelength flexibility
• Future applications may exceed OM4 distance limits

Therefore, genuine future-proofing comes from matching the fibre type, cable construction, connectivity, pathways and fibre count to a planned migration strategy.

Frequently Asked Questions About OM4 Fibre Optic Cabling

What is OM4 Fibre Optic Cabling?

OM4 Fibre Optic Cabling uses 50-micron, laser-optimised multimode fibre designed for high-speed optical transmission. It provides an effective modal bandwidth of at least 4,700 MHz·km at 850 nm.

Consequently, OM4 can support higher data rates or longer distances than earlier multimode fibre categories.

What is the difference between OM3 and OM4 fibre?

OM3 and OM4 both use a 50-micron core and support 850 nm laser-based transmission. However, OM4 provides higher effective modal bandwidth.

OM3 provides at least 2,000 MHz·km at 850 nm, while OM4 provides at least 4,700 MHz·km. Therefore, OM4 can support longer distances for some applications and provide greater optical performance margin.

Can OM4 support 40 Gigabit Ethernet?

Yes. OM4 commonly supports 40GBASE-SR4 channels up to 150 metres.

However, the actual channel must comply with the applicable IEEE standard and remain within the permitted insertion-loss budget. Therefore, designers should verify the transceiver and equipment specifications before installation.

Can OM4 support 100 Gigabit Ethernet?

Yes. OM4 supports several 100 Gigabit Ethernet optical interfaces.

For example, commonly specified 100GBASE-SR4 and 100GBASE-SR1 interfaces can support channels up to 100 metres over OM4. However, fibre counts and optical lane configurations vary between interfaces.

Consequently, designers must identify the exact transceiver before specifying the cabling system.

Can OM4 support 400 Gigabit Ethernet?

Yes. Specific 400 Gigabit Ethernet interfaces support OM4 multimode fibre.

For example, 400GBASE-SR4 can support up to 100 metres over OM4. Nevertheless, designers must confirm equipment compatibility, channel topology, fibre count and insertion-loss limits before selecting the cabling.

What colour is OM4 fibre optic cable?

Manufacturers and installers commonly use Erika Violet to identify OM4 cable and connectivity. For RapidConnect products, Erika Violet means RAL 4003.

However, jacket colour alone does not prove that a cable contains OM4 fibre. Therefore, buyers should always check the cable marking, datasheet, certification and test documentation.

Is OM4 better than OM3?

OM4 provides higher effective modal bandwidth and longer reach for some applications. Therefore, it offers stronger performance than OM3.

However, OM3 may still meet the requirements of shorter channels. Consequently, the better commercial choice depends on the transmission standard, channel length, equipment cost and future migration plan.

Is OM4 better than singlemode fibre?

OM4 and OS2 singlemode fibre serve different network requirements.

OM4 often provides cost-effective connectivity over short data centre distances. In contrast, OS2 supports much longer distances and provides greater long-term reach flexibility.

Therefore, designers should choose the fibre type that best matches the application rather than treating one as universally superior.

How far can OM4 fibre transmit?

OM4 transmission distance depends on the selected network application.

For example, OM4 commonly supports 10GBASE-SR up to 400 metres, 40GBASE-SR4 up to 150 metres and many current 100G or 400G short-reach interfaces up to 100 metres.

However, designers must always verify the exact IEEE standard, transceiver specification and optical loss budget.

Is OM4 suitable for outdoor installation?

The OM4 fibre itself can operate inside many cable constructions. However, the outer cable must suit the environment.

For outdoor installation, designers should specify a cable with appropriate water blocking, jacket materials, tensile strength, crush resistance and environmental protection.

Therefore, an outdoor loose tube or Mini Loose Tube construction may suit conduits, ducts and inter-building pathways better than a standard indoor cable.

Should data centres use pre-terminated OM4 fibre?

Pre-terminated OM4 fibre can provide significant advantages in data centres. Manufacturers install and test the connectors before delivery, which reduces on-site termination work.

Consequently, pre-terminated systems can accelerate installation, improve consistency and simplify commissioning. However, designers must specify the correct length, fibre count, cable construction, connectors, breakout lengths and polarity before manufacturing.

Conclusion

OM4 Fibre Optic Cabling remains an important part of next-generation data centre infrastructure.

It supports high-speed transmission, provides longer reach than OM3 for many applications and allows operators to use cost-effective short-reach optical transceivers. Furthermore, it supports a wide range of Ethernet and Fibre Channel applications across typical data hall distances.

However, designers must specify OM4 as part of a complete optical system. They need to consider the network interface, channel distance, fibre count, connector losses, cable construction, installation environment and future migration path.

Within data halls, factory-tested pre-terminated OM4 systems can accelerate deployment and improve commissioning consistency. Meanwhile, compact loose tube cabling can extend OM4 connectivity through outdoor conduits and demanding campus pathways.

Anderson Corporation supplies OM4 fibre optic cabling for Australian data centres, enterprise networks and infrastructure projects. Available constructions include tight-buffered, indoor/outdoor, loose tube, Mini Loose Tube and custom pre-terminated fibre optic cable.

Contact Anderson Corporation for assistance selecting the correct OM4 fibre type, cable construction, fibre count and termination configuration for your project.