CityFibre on The Need to Keep Fibre Optic Broadband Dust Free

One of the most common challenges when deploying and maintaining “full fibre” (FTTP) broadband ISP networks is the impact of dust. A single microscopic speck of dust – impossible to see with the human eye – could feasibly lead to a data communication failure and create performance problems for thousands of customers.

All of this becomes a bit easier to understand when you consider that a single fibre strand, carrying pulses of light from a laser, is no thicker than a human hair. In order to see such dust, you’d need a microscope. The presence of dust impacts the transmitted light by causing signal degradation as it absorbs, refracts or reflects some of the light being sent down the fibre.

On top of that, dust can also create permanent defects on the fibre (microscopic scratches or pits), which is another challenge. Plus, any debris that gets inside can then break up and spread wider. Sadly, you can’t just solve all this by wiping the dust away manually because the contact friction, and resultant electrostatic charge, will end up drawing oppositely charged microscopic dust particles onto connector endfaces (like a magnet).

Suffice to say, keeping the endface of such fibres clean is a constant concern for, we hope, every network operator (i.e. dust is to fibre connections, what water ingress is to copper lines). Most modern fibre exchanges are thus built with climate control and dust-filtration, but this won’t catch everything, and ultimately it’s up to the engineers to follow the best possible practices.

CityFibre has just published a useful editorial on this common, albeit rarely discussed, challenge. The article attempts to highlight the benefits of taking a zero-tolerance approach to cleaning practices. Indeed, out of the many tens of thousands of connections made in their Fibre Exchanges (FEXs) last year, they claim not to have suffered a single failure due to dust.

City Fibre’s Position

By investing in the right tools and technology and enforcing a zero-tolerance policy on poor fibre inspection, cleaning and testing processes though, we’ve proven that it is possible to prevent dust and debris causing any issues within our FEXs.

Complacency is the enemy of the fibre network though, especially in a FEX. Once a connection is in and the first customer is live you can’t just go back later and disconnect a fibre just to clean it – not unless a fault is reported. It’s therefore essential to ensure steps are followed correctly at the outset. It might take three, five or even ten times longer to do these steps right, but it can be the difference between having to return next week or never!

All the third-party fibre engineers who touch our network (as well as our own people) are required to have the right testing and cleaning equipment. They must then use it to test and clean every fibre connection, every single time with no exceptions. Once ‘scoped’ and cleaned, a pass/fail software check must then be run. If it fails, the clean and test process must be repeated as many times as needed to secure the pass result. Photographic evidence of good connections and successful tests are also required by us.

Today in CityFibre, “Inspect and clean before you connect” is the mantra that every engineer working on our network knows and respects. We acknowledge though that if they didn’t have to inspect and clean fibres meticulously, they could do four to five times more FEX fibre patching jobs each day. This means it’s important to make our quality over quantity priorities crystal clear. It’s not until you see the results of a correctly followed end-to-end process though, can you truly appreciate why this approach is worth it.

At this point we should highlight that we don’t know a huge amount about how different operators in this industry approach cleaning, which makes it hard to construct a useful comparison. Likewise, there’s virtually no solid or accessible data on how many failures, or performance problems, within each operator actually end up being attributed to dust.

Put another way, it’s hard to know whether CityFibre’s approach is the exception to the rule or the norm, but either way we don’t tend to hear much about dust related connection faults. The assumption being the majority of operators probably have a reasonably effective approach to cleaning. We’d welcome feedback from other operators on this.