FOCUS on CONNECTIVITY
OVERCOMING OM3 PERFORMANCE CHALLENGES
First Third-Party Test of Pre- Terminated OM3 MTP System Demonstrates Flexibility in 10G Network Designs
10 Gigabit Ethernet (10GbE) introduces a challenging 2.6 dB insertion loss limit on OM3 fiber cabling. This tight limit has led some industry observers to suggest it’s not possible to meet the standard using regular, as opposed to low-loss, MTP® cassettes. These observers have also suggested it’s not possible to run fiber cabling the full 300-meter distance specified in the 10GBASE-S standard when using MTP cassettes, whether standard or low-loss.
To test these assumptions, Leviton contracted with Intertek Testing Services (ETL) to perform benchmark testing of OM3 fiber system performance. The testing proved that the 10GBASE-S standards can easily be met with the latest generation of OM3 fiber systems using standard MTP cassettes and up to the full 300-meter length limit. In addition, the results show that Leviton’s OM3 system will support future migration to 40GbE/100GbE applications.
MULTIMODE FIBER –STANDARDS, APPLICATIONS, & CHALLENGES
For many years 62.5/125 µm (OM1) and conventional 50/125 µm (OM2) multi-mode fiber have dominated shorter distance communication applications, such as within a building or on a single-site campus. The fibers easily support applications ranging from 10 Megabit Ethernet (MbE) to Gigabit Ethernet
MTP Cassette Type
Connector Mated Pairs Type LC SC
Leviton Typical Insertion Loss .50 .55 .50
Leviton Typical Insertion Loss .15 .20 .15 .35
Figure A: OM3 fiber insertion loss performance (dBs)
(GbE). Their relatively large core sizes simplify connections and are ideal for use with low cost light-emitting diode (LED) transmitters.
With the introduction of, and demand for, 10 Gigabit Ethernet (10GbE), typical in data centers, the physical limitations and properties of multimode optical fiber are being severely tested. Multimode fiber provides many allowable paths for light to travel down the fiber, and due to intermodal dispersion not all pulses arrive at the destination simultaneously. This characteristic, as well as other issues, ruled out the use of OM1 and OM2 fiber in 10GbE networks.
To address this, the Institute of Electric and Electronic Engineers (IEEE) created the 10GBASE-S (the S stands for short wavelength) multimode fiber specification with the goal of providing 10GbE operating distances of 300 meters. Laser-optimized OM3 fiber was
Figure B*: Configuration 1 - 300-meter channel with 6 mated pairs. Average maximum channel insertion loss was 2.04 dB, resulting in a 0.57 dB margin under the 2.6 dB limit.
specified in TIA-492AAAC to support both the IEEE standard and economical vertical cavity surface emitting lasers (VCSELs) that operate at the 850 nm and 1300 nm wavelengths. Fiber that meets the standards delivers an effective modal bandwidth of 2000 MHz*km at the 300 meter distance.
The TIA-568-C.0 standard allows for a maximum 2.6 dB insertion loss and 300 meter length with OM3 fiber cabling systems. While manufacturers frequently submit their copper cables for third- party testing to verify performance that meets or exceeds applicable standards, they typically have not had fiber cabling systems, including OM3, tested. As a result, designers and operators of OM3 fiber networks are uncertain what the true parameters are in designing premises applications.
For example, the maximum insertion loss for
Leviton Maximum Insertion Loss .75 .75 .75
Leviton Maximum Insertion Loss .25 .25 .25 .50
TIA Maximum Allowable Insertion Loss 1.50 1.50 1.50
TIA Maximum Allowable Insertion Loss .75 .75 .75 .75
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