Two families, not four grades of the same cable
OM3, OM4, and OM5 are 50/125 µm multimode fibres. OS2 is singlemode. You cannot mix a multimode transceiver with singlemode fibre, or the reverse, and expect the link to come up. The optic and the fibre have to be chosen together.
Within multimode, the grades differ by bandwidth. Higher bandwidth supports faster optics over a longer distance. The distances below are typical published reaches for common short-reach optics. The exact reach depends on the transceiver and the standard it claims, so treat the table as a comparison, not a design guarantee.
| Type | What it is | Typical role |
|---|---|---|
| OM3 | Multimode, laser-optimised | 10 Gigabit over a few hundred metres; shorter at 40/100 Gigabit |
| OM4 | Higher-bandwidth multimode | Longer multimode reaches than OM3, including 40/100 Gigabit SR4 |
| OM5 | Wideband multimode | Short-wave division multiplexing; rarely required unless specified |
| OS2 | Singlemode | Long reach and the usual choice for new high-speed backbones |
How to choose
If the switches already have multimode optics and the runs stay inside a building or a short campus, OM4 is the safer multimode choice over OM3. OM3 still works where the distance and the optic are within its reach and the cable is already installed.
OM5 costs more and helps only when the design uses wideband or short-wave division multiplexing optics. For a normal duplex 10 Gigabit or a parallel 40/100 Gigabit multimode link, OM4 does the same job.
OS2 is the default we suggest when the link is long, leaves the building, or is a new data-centre backbone. Singlemode optics have become ordinary, and the fibre does not have to be replaced when the speed moves from 10 Gigabit to 100 Gigabit and beyond. Do not splice OS2 into an OM4 plant; they are different systems.
What else has to match
Connector type (LC, SC, MPO), polarity, fibre count, and indoor versus outdoor or universal construction matter as much as the OM or OS grade. A panel, cassette, and patch cord have to be the same fibre family as the trunk.
AmberWork Source stocks CommScope fibre cable, panels, cassettes, pigtails, and patch cords in Singapore. Send the link schedule with fibre type, count, and connector for a quotation.