OM3 and OM4 multimode fiber cables have the same connector’s terminations, the same transceivers, and the same fiber core size. They are two common multimode fiber types used in backbone cabling between telecommunications rooms and in the data center between main networking. Besides, they’re fully compatible. So what is the difference between them?
As a matter of fact, the main difference lies on the construction of the fiber cable. OM4 fiber cable has a different internal construction within the 50/125 core thus it has better attenuation and can operate at much higher bandwidth than OM3. OM3 allows maximum attenuation at 850nm under 3.4db/km, OM4 allows under 3.0db/km. Minimum fiber cable bandwidth of OM3 at 850nm is 2000MHz/km while OM4 is 4700MHz/km.