These letters reference the type of transmission of the cable, with MM for Multi-Mode and SM for Single-Mode and the standards are based on Optical Multi-Mode (OM) such as OM1 to OM5 and Optical Single-Mode, such as OS1 cables, so that you match up the correct fibre leads and understand the capabilities of the cable.
OM4 is our current recommendation for new fibre optic connections.
The OM4 standard supports 10 GbE for links of up to 400m (potentially further) and is also bester suited for newer 40 GbE and 100 GbE applications.
When 10 Gigabit Ethernet (10 GbE) was introduced, we recommended/installed OM3 grade for links of up to 300m and it supports Gigabit links for connections up to 800m.
OM2 cable had a smaller core size (50/125μ) and could support Gigabit for longer lengths (up to 550m), but suffered the same fate as OM1, when 10 Gigabit Ethernet (10 Gbps) was introduced for backbone links (max length = 82m), so now this cable is no longer recommended.
The original cable used when Fast Ethernet (100 Mbps) was the common solution, from the 1990’s and it was considered ideal as it supported links of up to 2Km. You can check if your cable is this specification if it has 62.5/125μ on the sheath, as this relates to the core/cladding sizes
There was a shock when Gigabit Ethernet (1000 Mbps = 1 Gbps) was introduced, as this cable did not cope very well with this standard (maximum 275m depending on quality) and for many clients these cables had to be replaced, especially if 10 Gb Ethernet was considered (max length = 33m).
Why not use OM5?!
A new classification of fibre optic multi-mode was changed to OM5, after previously referred to as Wide Beam Multi-Mode Fibre (WBMMF) and it is optimised for higher speed applications.
Due to the nature of most network requirements, the additional cost for this grade of cable cannot be justified, so is not currently included in our recommendations.
Single-mode fibre optic cable is normally used for long links (up to 40Km) and so the laser technology in the transceivers is more expensive (than multi-mode grade), so for most applications single-mode cables are not required.
We will discuss options and associated costs when providing your solution.
We consider where the cable will be fitted when selecting the cable sheath, as there are options for reinforcement to protect against rodents, or if direct burial.
You also need to consider susceptibility to hazards such as chemicals.
Fibre optic cables may be supplied pre-terminated , as this potentially reduces time and costs,
However for most sites this is not always practical due to the size of holes that must be drilled through all wall/floors and so the increases complexity of the project.
Also, you must know the desired length when ordering the cable, so you will not be able to accommodate changes due to obstacles you find during the installation