CABLExpress® Cable Talk™ #19 - Fiber Polarity Methods
Fiber Light Path / Polarity
Today we’re gonna talk about fiber light path or polarity.
Fiber light path or polarity is very important. If it’s done and managed properly you don’t have to think about it. If it’s done incorrectly or not managed properly it can lead to downtime, and nobody wants that.
Simply put, it’s when you go from the send on one transceiver to the receive on the other transceiver. But things can get complicated very quickly if you’re talking about a whole channel which would involve fiber optic modules, the use of MPO trunking and multiple jumpers.
There are three approved methods defined by the TIA in the 568B standard documents. These standards were developed to offer migration paths to future speeds and technologies as well as options for manufacturers of associated products.
Method A relies on the cross to happen in one jumper. This could be difficult because you have to manage two different types of jumpers.
Now I’m going to jump down to Method C because it’s very much like Method A, however, the cross occurs in the trunk. Since these aren’t off-the-shelf items - they’re usually custom built for you - it’s not gonna be as difficult to manage.
And then back to Method B: this is where the cross occurs in the module itself. Again you’re gonna have to rely on managing two different types of modules.
Our Skinny-Trunk® Solution utilizes Method C. We chose this as it aligns with our philosophy which is a structured cabling solution that can maximize return on investment and last through generations of hardware up to 100 gigabit speeds. And while we utilize Method C, we can build this to any customer or unique applications needs.
It is not recommended to mix light path methods within any particular site. It is important to plan carefully, document well, and fully understand the polarity of your fiber optic infrastructure.