Insertion loss budgets have gotten tighter as we have moved from 10 to 40/100 Gig for multimode fiber applications. One would think that we can’t say the same for singlemode applications that have historically meant larger loss budgets – 6.3 dB for 100 Gig over singlemode (100GBASE-LR4) versus just 1.9 dB for 100 Gig over multimode (100GBASE-SR4). But that’s no longer the case with new short-reach singlemode applications. And it’s not just insertion loss that matters with these applications; you now need to also be concerned with reflection.
Let’s take a look at the #9 Dumb Thing that smart people do when testing network cabling systems—relying on a duplex tester for certifying MPO trunks. Field testing is the only way to ensure that MPO links meet the application performance requirements. Despite the fact that pre-terminated MPO fiber cables are manufactured and tested by vendors to comply with ANSI/TIA and international standards, there are many factors that can potentially impact performance. First of all, MPO connectors are harder to clean than duplex connectors. The 12-fiber MPO interface features an array with a much larger surface area, which unfortunately makes it easier to move contaminants from one fiber to another within the same array during the cleaning process. 40 and 100 Gbps MPO fiber applications also have much lower loss budgets so it’s important to ensure the highest testing accuracy as possible.
Fluke’s CableIQ Qualification Tester helps you determine whether the cable you’re using will work properly and provide the bandwidth needed for your application, troubleshooting and qualifying Ethernet cabling speed (10/100/1000 VoIP).
Let’s take a look at the #6 and #7 Dumb Things that smart people do when testing network cabling systems— Using a non-EF compliant tester for testing multimode fiber and choosing the two-cord reference for Tier 1 optical loss testing.
Top #Troubleshooting Tips: Did you know that the Real Time Trace feature on your #OTDR allows you to perform the “Wiggle Test” to identify a loose or damaged connector?
A speck of dust you can’t see on an MPO connector can bring down a high-speed trunk, potentially affecting thousands of users. This video covers techniques for cleaning MPO connections using both dry and wet methods and shows how fast and easy it is to inspect them to make sure the job is done right.
Is OM5 needed? Last year the IEEE P802.3cm task force began working on a new standard for 400 Gb/s over multimode fiber that in addition to 400GBASE-SR8 over eight lanes (16 fibers total) using 24- or 16-fiber MPO connectors also includes 400GBASE-SR4.2 that operates over four two-short wavelength division multiplexed (SWDM) lanes (8 fibers total) using a standard 12-fiber MPO. Since OM5 is optimized for SWDM, this could finally push it into the limelight. However, since the new standard leverages existing two-wavelength technology that will ensure operation up to 100 meters of OM4 cabling, the question remains as to whether people will make the leap.
Contaminated connections are the number one cause of fiber-related problems and failures in a data center, Enterprise backbones and other fiber networking environments. The #10 most common cabling mistake is skipping out on proper fiber inspection! One tiny speck of dirt on the fiber core can cause loss and reflections that increase error rates and degrade performance.
Contamination remains the number one cause of fiber link failures. Defects on a fiber end-face come in all types, shapes and sizes. They include scratches, cracks, and pits and contaminants like dirt, dust, oil and even salt. If you properly clean a fiber end-face with lint-free wipes and a specialized solvent designed specifically for fiber cleaning, it’s possible to remove contaminants from the fiber end-face. But what about permanent surface defects like scratches, cracks and pits that can’t be removed via cleaning?
Understanding loss means you can design networks properly, identify the good and bad in the network design, and then solve problems more easily. We are starting to see loss budgets get tighter and reflectance standards actually being enforced because speeds are going higher. Understanding how loss and reflectance work and how to work with a loss budget helps you to look and identify the good and bad in the networks design.