The ABCs of TIA-568

The ABCs of TIA-568

By: Kent Goldsmith | Engineering Manager

Layer one technology is all about the quality of the overall product. Fiber light path is a key component that needs to be managed properly to avoid downtime. To ensure your data center can support higher data rates, there are three methods defined in the TIA-568 standard referred to as methods A, B, and C.

These methods were developed to guarantee proper fiber system connections and migration paths to future speeds. They work well for duplex transmissions as well as MPO-based parallel transmissions like 40G/100G. It’s important to understand all of these methods and be able to adapt to different ones.

Method A

For duplex transmissions, method A uses straight-through modules and a straight MPO/MPO trunk. The MPO/MPO couplers in this method are industry-standard key-up to key-down couplers. A key-up key-down coupler yields an MPO position 1 to MPO position 1 mating scenario which makes it nice and simple.

The main factor to remember about method A is that it requires two different kinds of jumpers to be deployed at the ends of the link. One end has an industry-standard crossed duplex jumper and the other end must have a non-standard straight jumper.

Method B

Method B uses a flipped MPO/MPO trunk (MPO position 1 to MPO position 12). This trunk is deployed between two different modules. One module is an alpha module and the other is a beta module. The jumpers on both sides of the link are industry-standard crossed duplex jumpers.

The important factor to keep in mind about this method is that the MPO/MPO couplers used are non-standard key-up to key-up style, which yields an MPO position 1 to MPO position 12 scenario when mated. This adds complexity and can sometimes lead to significant issues with single-mode cables. All MPO single-mode connectors are APC and have an 8-degree angle polish.

Method C

Similar to method A, method C is quite possibly the most prevalent one deployed today. It uses a pairwise crossed trunk with straight modules. The MPO couplers are also industry standard key-up to key-down. This method requires very little thought about which modules are on each side and which type of jumper is used on each side. All modules are straight and all duplex jumpers are industry-standard crossed type. 


In this Respect Layer One® video, Josh Taylor, Product Manager of CABLExpress, discusses the three TIA-approved fiber polarity methods when using the MPO style (MTP®) connector in the data center.


Preparing for the Future

With the introduction of the IEEE 802.3bm standard we need to start thinking about how to merge the light paths of various methods for duplex transmission and parallel transmission. It is common to have a 40G transceiver on one end and 10G duplex transceivers on the other end.

Special consideration needs to be given for the best way to merge these two types together. Experienced partners like CABLExpress can assist you in this process and supply structured cabling solutions that will maximize return on investment. Prepare your infrastructure for a successful future that will last you through generations of hardware up to 100 gigabit speeds.