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Selection of Optical MultiMode Fibre Cabling

In summary the volume of data passing over corporate networks has increased at a staggering rate over recent years. In addition technology has become a vital part of everyday business life and investment in these systems has therefore also grown at a similar pace. Furthermore Optical MultiMode Fibre and Singlemode Fibre have been part of that acceleration

To illustrate developments in technology such as desktop virtualization and unified communication tools have placed further strain on the network Thus the importance of data cabling has increased as part of the wider ecosystem that impacts the end user.

Therefore IT cabling, be it copper or fibre, tends to evolve with the new hardware being produced. Therefore it is important that sufficient focus is placed on the choice of cabling as part of a well rounded IT solution.

Recognise the significance of your cabling choices

Choosing specifically the correct fibre optic cabling will ensure that you get the best possible performance from your IT infrastructure. Furthermore providing users with fast access to the large amounts of data they need. This in summary maximizes the productivity and effectiveness of the workforce.

For example failure to give proportionate attention to network cabling will hamper performance. Furthermore it will ultimately undermine investments that have been made elsewhere.

Meanwhile the international standard ISO 11801 specifies four main classes of multi-mode optical fibre cables. For the most part they are based on the modal bandwidth. Likewise this  has helped to simplify the process for choosing the appropriate cabling. In fact that choice is ever more important for the correct operation of your technology

  • OM1 – 62.5µm core; 200 MHz-km @ 850nm
  • OM2 – 50µm; 500 MHz-km @ 850nm
  • OM3 – 50µm; 1500 MHz-km @ 850nm
  • OM4 – 50µm; 3500 MHz-km @ 850nm

For this purpose differing bandwidths of these cables allow high network speeds to be maintained over longer transmission distances.

Optical Multimode Fibre Comparison Chart


Minimum modal bandwidth
850 nm / 1310 nm

100 Mb Ethernet 100BASE-FX

1 Gb (1000 Mb) Ethernet 1000BASE-SX

10 Gb Ethernet 10GBASE-SR

40 Gb Ethernet

100 Gb Ethernet

OM1 (62.5/125) 200 / 500 MHz·km up to 2000 meters (FX)[11] 275 meters (SX)[11] 33 meters (SR)[11] Not supported Not supported
OM2 (50/125) 500 / – MHz·km up to 2000 meters (FX)[11] 550 meters (SX)[2] 82 meters (SR)[2] Not supported Not supported
OM3 (50/125) *Laser Optimized* 1500 / 2000 MHz·km up to 2000 meters (FX) 550 meters (SX) 300 meters (SR)[11] 100 meters[2]330 meters QSFP+ eSR4[12] 100 meters[2]
OM4 (50/125) *Laser Optimized* 3500 / 4700 MHz·km up to 2000 meters (FX) 1000 meters (SX)[2] 400 meters (SR)[13] 150 meters[2]550 meters QSFP+ eSR4[12] 150 meters[2]


Cable Comparison Summary

For instance, the industry standard minimum reach for OM3 cable at 10 Gbit/s speed is 300m. However while OM1 is capable of supporting similar speeds, this only holds true over short distances. OM4  however can maintain it over an even longer distance (550m).

OM1 is therefore more widely used at the slower speed of 1 Gbit/s. For this reason it supports a transmission reach of 275m.

In the past, people were generally content with the 1 Gbit/s speeds that were possible with OM1. However in more and more cases this is no longer sufficient.

Indeed in our experience working with a range of clients, we are finding more people wanting to upgrade from OM1 to the laser-optimized OM3. Thus facilitating faster network speeds and greater bandwidth.

Performance vs. Distance vs. Cost

Therefore the decision as to which optical multi-mode cable to choose ultimately comes down to a question of performance requirements, distance and cost.

Generally the ISO 11801 classifications have greatly simplified this decision making process. To begin with by defining an industry minimum standard reach for varying levels of performance.

Therefore OM3  and Om4 are becoming the norm to achieve a 10 Gbit/s network. Subsequently this is suitable if you require consistently high speeds to support a range of IP based technologies across your site.

In conclusion if you are unsure which cabling solution is right for you, NM Cabling offers a free network survey. In addition this includes expert advice on your options for installing, upgrading or growing your existing network.

Similarly this document can be viewed as a PDF file Simplifying the Selection of Optical Multi-Mode Fibre

Accordingly for  more information on Fibre Optic Cabling Contact NM Cabling  01923 888588 or see our page on Fibre Optic Cabling Installations