JOHN WILLIAMSON OPTICAL NETWORKS
routes from source to destination, and operators can protect against multiple fibre breaks. VIAVI makes the distinction between spare capacity and load sharing on redundant paths. “The idea is if you have two paths between points ‘a’ and ‘b’, with proper load sharing, you have enough capacity to dial up payload in near-real- time if one path fails,” notes Rowan. “Load sharing should be a bigger factor than spare capacity – although the two are closely related.” But not all optical links are equal. “Everything needs to be seen in the context of economic viability. The more revenue generating - or mission-critical - traffic is on the fibre, the easier it is to justify additional or more sophisticated protection schemes,” comments Rettenberger. “On the other hand, best- effort residential broadband is typically not very well protected, and operators are just looking to keep repair times low.” Even so, Gonzalez reckons there are advances in cabling for FTTx which make it more resilient than some other applications. He instances hardened connectors that make FTTH installations truly plug-and-play, minimising the risks of connection errors, accidental release, and therefore less likelihood of service interruptions. WHATEVER NEXT? Bolstering optical network resilience is not a static enterprise, and a number newer technologies and tools are coming into sharper focus. One such is active fibre monitoring. “Operators are increasingly interested in active fibre monitoring solutions. These detection systems flag an alarm if the fibre quality is impaired and an outage is likely to happen in the near future,” explains Rettenberger. “Active fiber monitoring as an additional safety blanket is relatively new and gaining commercial traction. We expect this to be more widely deployed going forward.” “Such fibre monitoring solutions are cost-efficient, provide an additional safety layer and improve resiliency in
areas where having idle spare capacity is not possible or cost-prohibitive,” he concludes. VIAVI suggests there’s additional mileage in better managing the combination of technician skill set and keeping pace with persistent fibre network advancements. “Fibre is everywhere. More people are working on it with less experience, so having a knowledgeable and skilled crew matters, but you also need to support those who are new or simply less skilled,” suggests Rowan. “And having tools that are designed for ease of use, automation, and all users – not just experts – is key in the access side of the network.” This is especially the case in FTTH environments. EXFO is also an advocate of more automation, identifying one trend as being the use of remote, cloud-based network monitoring solutions. “These solutions that can provide end-to- end network performance visibility for live Key Performance Indicator (KPI) reporting and Business Intelligence (BI) dashboards will be in high demand,” predicts Gagnon. “As well, automated field testing tools and software that can give technicians insight quickly and easily to identify and solve issues will continue to be required to ensure reliability and maintain uptime.” And for its part CommScope recommends using hardened connectivity terminals as one of the best ways to boost optical network resilience. Gonzalez points out that traditional methods of placing and splicing fibre cables take time and can lead to risk of downtime. “We expect to see the increased adoption of hardened connectivity solutions improving optical resiliency, as well as pre-connectorised solutions,” he states. “Hardened connectivity has consolidated as the main technology used for outdoor distribution.” CUT-OFF POINTS As remarked by Rettenberger, there’s a whole litany of phenomena that can damage or sever fibre cable. For aerial deployment, it could be adverse weather, natural disasters, or traffic accidents felling poles. Buried cable can be at the mercy of earthquakes, later adjacent construction or civil works and, in some geographies, wild animals. What about LANs? “Here I would say ‘home/office improvement’, construction work and careless behaviour from users on site are the main reason for fibre breaks,” states Rettenberger. But in any event, not all of these causes of service outages lend themselves to ready autonomous restoration fix-its.
by simply switching the adapter,” says Gagnon. But there’s a caveat.
“On the other hand, having too many functions in the same platforms, like fibre inspection and power meters, can limit the multi-tasking efficiency for a team in the field and increase the bulkiness and price of simple equipment,” he observes. “So fit-to-purpose test equipment is usually preferred for simple tasks.“ In practice, fibre monitoring systems play a large and expanding role in promoting overall network resilience. “Fibre optic monitoring is perhaps the biggest component to ensuring overall network resilience – to include test and documentation at installation, followed by reliable monitoring for breaks, intrusions, and disruptions in general.” asserts Rowan, but there’s a caveat here too. “Network monitoring is only as good as the documentation you have,” cautions Rowan. “Knowing there is a break is not enough, you need to know where, why, and how. This requires a well- documented network.” ESCAPE ROUTES Creating redundancy is an obvious way to enhance optical network resilience. Some different topologies are evident here. As Stephan Rettenberger, ADVA’s SVP of Marketing and Investor Relations points out, for DCI purposes, operators typically use redundant point-to-point links, with two separate fibres in separate cables being buried in separate ducts and taking different routes between the locations, even entering and exiting the building on opposite sides. “On top, they have multiple failover mechanisms on the equipment level,” he says. For the MAN, a multi-fibre ring is the most common topology, enabling switching between fibres, and making two routes always available to get from source to destination. “If there’s a break on the clockwise route, traffic can be switched to the counter-clockwise route and still reach its destination,” observes Rettenberger. Meantime, long-distance networks are often built in a mesh. This means that there are even more than two
Étienne Gagnon SVP, Test andMeasurement Division, EXFO
Jose Luis Gonzalez FTTHNetwork Architect, EMEA, CommScope
Stephan Rettenberger SVP, Marketing and Investor Relations, ADVA
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| ISSUE 29 | Q2 2022
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