At Submarine Networks Europe 2018, a host of delegates came together to discuss the lifespan of submarine cables, debating the issue of ‘Is 25 years too long?’ 

The discussion

To encourage debate, the group entered into a lively discussion on the following questions

  1. Who needs a shorter lifespan for their cable systems and why?
  2. What will need to change from a system design and cost perspective to achieve a desired shorter lifespan?
  3. What will the variety of lifespans on offer to the market do to the perceptions of reliability on undersea systems
  4. What are the advantages and disadvantages of long vs shorter lifespan systems?

The panel session on cable lifespan proved to be a popular one, with the attendees discussing the lead-in questions above, and a unanimous additional question of ‘is 25 years too short?’

The hot topic was ‘who is asking for shorter lifespans and why?’ Though the content players were not represented on the roundtable, it was universally acknowledged that they were pushing the industry to consider cheaper systems that might only be designed for a useful economic lifespan of 8-15 years, rather than the 25 years preferred by the carriers, some owners who were actively seeking to repurpose older systems for a second life, and others who were seeking to extend the economic life of their existing systems.

Key findings

Clearly this divergence of opinion stirred debate in the group and surprisingly, it wasn’t those on the supply side that were pushing the notion of ‘disposable systems’ even though they would benefit more through increased sales.  To get right into the topic, the group considered some of the issues and challenges that anyone seeking to reduce (or increase) system lifespan must consider and their findings were as follows:

  • Shorter lifespans don’t work for underserved markets with less route diversity – they want reliability, not disposable systems.
  • Halving the lifespan of the system doesn’t halve the cost. Some costs, such as survey and installation, are (almost) fixed, so the imagined savings may not be as great as expected, though incremental savings of shorter lifetime systems may be realisable.
  • There is an ongoing challenge of keeping the costs of upgraded older systems competitive when compared with the newer generation of systems that were designed to work at massively greater capacities. Every system will eventually reach a point of economic unviability.
  • The perception of ‘disposable’ systems is less attractive to those who sell capacity on those systems, leading to challenges in persuading customers to commit to capacity at a much earlier phase of system life.
  • Why reduce lifespan? Answer: to cut costs. However, see the earlier answer reflecting that there is a trade-off between designing for a reduced lifespan, and achieving the lowest cost for capacity in the long term.
  • Carriers are seeking to extend the lifespan of their systems where it makes technical and economic sense to do so. This is forging a new path of reducing reliance on consuming new resources (good environmentally) and can be achieved for those systems that have aged better than expected, have been cared for better through their lifetime, and generally reject the notion that cable networks should be treated (for instance by content players) as a ‘consumable’ item. This rather promotes a ‘good stewardship’ ethos – much better environmentally. System health can be monitored throughout life, and so the conventional ‘bathtub’ curve of failures may extend beyond originally planned system life (the ‘extending bathtub’) and lead to many more years of reliable service.


The discussion ended with some short bullets distilled form the debate:

  • If it ain’t broke, why retire it?
  • There is an economic changeover point between fixed and variable costs that occurs even on a short lifespan or cost-reduced cable system.
  • There is a negative environmental connotation of treating cable networks as a throwaway commodity and those who seek to do so should consider their environmental credentials a bit more carefully!
  • However, repurposing healthy short-lifespan cables may assist those in underserved communities if those cables could be repurposed and redeployed.
  • Though some are seeking to break the industry’s reliance on a 25 year design/economic life, the reality is much more complex and every project will be different.
  • But the industry has to plan now for a ‘post-Shannon-Limit’ world where massive capacities will only be able to be achieved by designing high fibre count repeatered cables – the revolution is coming!’

Important takeaways

  • Don’t ignore the lifetime vs cost ‘sweet spot.’
  • Those who are seeking to reduce cable lifespans should make their case – conflating economic lifespan might simply be a smokescreen for ‘cut your prices and I don’t care if you don’t reduce your quality.’

Let the debate continue!


Keith Schofield was a speaker at Submarine Networks Europe in London. The event, organised by Total Telecom, will be back in 2019, find out more at