What is OM5
How OM5 differs from OM3 and OM4 and whether they are compatible
As data centers have become larger and larger in recent years, there is a growing demand for more bandwidth and faster data transfer rates. Recently, OM5 has been approved as a new type of high-speed multimode fiber (MMF) for data centers, and various discussions of its characteristics and features attract a lot of attention. This article will discuss some FAQs to help you get a clear understanding of OM5 fiber optic cable.
What is the OM5 cable standard
The Telecommunications Industry Association (TIA) initiated in October 2014 a working group to develop guidelines for the 50/125 µm Wideband Multimode Fiber (WB MMF) standard to support Short Wavelength Multiplexing (SWDM) transmission. The TIA-492AAAE standard was published in June 2016.
What makes the OM5 cable so distinguishing
OM5 is intended to support at least four wavelengths in the 850–950 nm range to optimally support short wavelengths with Long Wavelength Division Multiplexing (SWDM), which reduces the number of parallel fibers by at least a factor of four to allow continuous use of only two fibers (rather than eight) for 40 Gb/s and 100 Gb/s transmissions and fewer fibers for higher speeds.
What is SWDM
Shortwave connections are typically powered by VCSELs (Vertical Cavity Surface Emitting Lasers) operating near the wavelength of 850 nm. Long Wavelength Division Multiplexing (SWDM) is a technology that uses four wavelengths in the range of 850–950 nm. SWDM transceivers have been designed to use two-wire communication in a transceiver with OM5 multimode fiber.
Is channel loss measurement needed at both 850 and 953 nm
No. Loss measurements on the 850 nm field channel can be used to demonstrate compliance with channel loss at 953 nm.
Can SWDM be used for OM3/OM4
Yes. SWDM transceivers are compatible with OM3/OM4/OM5 optical communication solutions.
What are the data rate and distances for SWDM
Standard | ОМ3 | ОМ4 | ОМ5 |
40G SWDM | 240 m | 350 m | 440 m |
100G SWDM | 75 m | 100 m | 150 m |
Which is the effective modal bandwidth (EMB) for an OM5 cable
EMB ≥ 4700 MHz・km at 850 nm
EMB ≥ 2470 MHz・km at 953 nm
Comparing OM3/OM4 EMB values with OM5 cable EMB value
EMB is only specified at 850 nm for OM3 fibers at 2,000 MHz km and OM4 fibers at 4700 MHz km respectively. OM5 EMB values are given at both 850 and 953 nm.
Is OM5 cable compatible with OM3 and OM4 fiber
Yes. OM5 cable is fully compatible with OM3 and OM4 cables.
Is OM5 specified in optical transmission standards such as Ethernet and Fiber Channel?
There are no transmission standards specifying OM5 or SWDM. Transmission standards typically include only one multimode fiber option, which is selected based on economic, commercial, and technical criteria. Parallel transmission is the default multimode fiber option for data rates of ≥ 40G.
Is OM5 multimode fiber compatible with existing optical transceivers?
OM5 fiber is not compatible with the existing optical transceiver. Generally, 40G and 100G SWDM4 optical transceivers can be used with OM5 fiber. The SWDM4 transceiver uses sophisticated Short Wavelength Multiplexing (SWDM) technology. Signals at four wavelengths (850 nm, 880 nm, 910 nm, and 940 nm) are transmitted over a single fiber, and only two fibers are needed for bidirectional transmission.
What sheath color is used for OM5 multimode fiber?
TIA has listed lime green as the official cable sheath color for OM5.
OM5 vs OM4: Does OM5 provide a longer transmission range than OM4?
In fact, for all current and future IEEE multi-mode applications, including 40GBase-SR4, and 100GBase-SR10, the maximum allowable distance for OM5 is OM4. Recent application testing with 40G-SWDM4 transceivers shows that 40G-SWDM4 can reach 400 meters over OM4 fiber, and over OM5 cable, the module can reach up to 500 meters. In addition, if non-IEEE-compliant 100G-SWDM4 transceivers are used in the data center, it has been proven that OM5 can support a range of 150 meters, which is only 50 meters more than OM4.
Cable type | ОМ4 | ОМ5 |
10GbE | 400 m | 400 m |
40GbE | 150 m | 150 m |
100GbE | 150 m | 150 m |
40G-SWDM4 | 400 m | 500 m |
100G-SWDM4 | 100 m | 150 m |
10GbE | 400 m | 400 m |
Is the cost of OM5 cable wiring lower
OM5 cabling will cost about 50% more than OM4. In addition, with the significantly reduced costs of single-mode transceivers due to silicon photonics technology and large-scale hyper-scale data centers in large volumes, more and more users will switch to single-mode transceiver modules.
Is an OM5 cable really necessary for higher speeds
All IEEE standards in the next 100/200/400G Ethernet generation will work with either SMF or MMF, but in most situations, these next-generation speeds will require single-mode fiber as the IEEE is always looking to develop future standards that work with the main installed base of cabling infrastructure, so customers can easily upgrade to new speeds. In addition, none of these current next-generation oriented IEEE standards will use SWDM technology.
Will OM5 generate higher density from a switch port
The data center uses 40GBase-SR4 to increase port density by breaking out 40G over 10G with an MTP breakout module or MTP breakout cable. This is also a benefit of the new 100GBaes-SR4 modules that use OM4 cables. However, if the data center manager decides to use 100G SWDM4 modules with OM5 cables, they will not be able to force their way into 25 Gb/s links, which will become a real problem as the 25 Gb/s ecosystems are fully developed and we start to see more than 25G on the server.
OM5 multimode fiber or SMF single-mode fiber: Which one to choose
While the price of single-mode fiber (SMF) has been declining recently due to new technologies, the cost of plug-in optics continues to limit the implementation of SMF in data centers. Compared to this, OM5 can multiplex four wavelengths ranging from 850nm to 953nm, quadrupling the data capacity while also reducing fiber cost. In addition, MMF has more advantages in installation, troubleshooting, cleanup, and general maintenance, making it the best solution when building data centers. However, the problem with MMF is the distance. The maximum distance will decrease as the data rate increases. Therefore, multimode fiber has a higher value for network owners up to 500m, and OM5 can bring up to 400Gbps up to 150m. For distances over 500m, single-mode fiber should be chosen.