An Interview with Brian Lavallée, Senior Director of Solutions Marketing, Ciena


Editor’s Note: On January 14, the world was riveted by the images of the eruption of the Honga Tonga Hunga Haʻapai volcano near Tonga.  While destruction on the islands of Tonga was severe, the death toll appears to have been relatively small, which some have attributed to the population’s experience in dealing with natural disasters considering Tonga’s location in the Ring of Fire.  From the submarine cable perspective, Tonga’s only international submarine cable, linking the main island to Fiji, was only a short distance from the underwater eruption and was knocked out of service, almost completely severing Tonga’s connection to the rest of the world. 

At SubCableWorld, we initially declined to cover the eruption and cable outage as information was difficult to obtain and was sometimes questionable in regards to reporting standards.  We preferred to wait and speak with an industry expert about the situation to obtain a more reliable perspective.  Fortunately, we were able to speak recently with Brian Lavallée, Ciena’s Senior Director of Solutions Marketing, who provided us with insights into the event and lessons that can be learned from it.  His comments are below.

Brian Lavallée: The situation on Tonga certainly is unfortunate and we hope for the best for the people there.  It was ironic that the day before the volcano erupted, Ciena held a webinar in conjunction with TeleGeography where we discussed the importance of redundancy for island nations and the role of satellite backup for islands that only have one submarine cable connection.

There have been a lot of reports in the press saying that the global network infrastructure is so fragile that if a single submarine cable is cut, an entire country is pulled off the grid.  Some of the reporting I’ve seen on the Tonga volcano is all doom and gloom for the Internet.  Cable cuts happen all the time, there are several cable cuts right now, and we don’t even hear about them.  The reason for that is because of automatic protection switching and re-routing of end-user traffic to other available cables.  In those cases, the users don’t even know there was a cut. 

Most countries, in fact, have multiple cables providing redundancy.  We know this because Ciena supplies automatic switching equipment to several cable operators that automatically switch traffic around faults, as necessary.  There’s redundancy in the data centers.  Most large data centers have multiple redundant paths going into them over terrestrial links and they also connect to multiple submarine cable connections.  So, what happened in Tonga was obviously very unfortunate, but kind of predictable.  If the only submarine cable feeding an island nation gets cut, and there is inadequate satellite backup, the situation will be serious. Tonga is not the only island natin to experience such a situation.

However, satellite connectivity is not always the perfect solution.  That particular eruption in Tonga put a lot of ash clouds into the air.  So even if you had ample satellite connectivity, you don’t know what that connectivity would actually be considering all that ash sitting in the air between the satellites and an island nation.

Regarding the cable cut, the question is always, “How long will it take to get it turned back up?”  Right now, nobody really knows, but weeks will be the minimum.  First, you have to get the ship there and the ship has to have the right equipment and personnel onboard.  Then you have to find the cable.  Let’s not forget that this was an undersea volcano and that means likely landslides and lava flows.  We don’t know how much of that is on top of the cable.  You have to find the cable where it’s not submerged by hundreds of tons of undersea rubble. 

Then once you find the cable, you have to pull it up.  And then there’s the whole question about the volcano itself.  Is it still active?  Will we be putting the ship and crew in dangerous waters if the volcano erupts again?  There’s a whole safety issue involved and the ship operators are taking this into account to protect their vessel, and more importantly, the personnel onboard.  We can’t predict volcanos well and having a ship right in the middle is worrisome.  You just have to look at the satellite pictures of that eruption and it’s clear that any ship in that area is at risk if the volcano is still angry. 

They will move the ship in when they believe the time is right, but there will still be work to be done.  You have to find the cable.  You can do an OTDR tracing where you shoot light into the fiber, have it bounce off where it’s disconnected and then estimate where it is.  That distance, however, doesn’t give you the GPS coordinates of the cable.  Cables snake; they’re not in a straight line.  And we know that there was a huge underwater landslide involved in this eruption that move a tremendous amount of material.  If the landslide has moved that cable, where you think the cable is based on the GPS data when the cable was laid could actually be kilometers away from its expected location.  We know the cable ship crew will do its best and hope that Tonga will be back online soon.

So what is the solution to the issue of small island nations that only have one or no cables?  It would be to build additional submarine cables so you could have redundant routes in and out of those countries and terminate them at more than one cable landing station so you don’t have any single points of failure.  But therein lies the problem.  If you have a country with a large population and economy, you could build a business case for multiple cables and landings.  Small island nations can’t always build that business case.  Submarine cables are very expensive.  You might be able to get a branching unit from a cable that’s luckily passing by your island.  That’s a possibility and would lower the cost, but having a submarine cable built that is connecting just your island is a major challenge. 

To help meet that challenge, there is a move in the industry to repurpose some of the older cables that have been discontinued. These cables are still in working order, but may have simply become economically unviable, say for a specific high-traffic submarine route. The undersea system is pulled up off the seabed, refurbished, tested, and sold to other countries, like smaller island nations that need redundancy.  Even when submarine cables start to reach end-of-life from a design perspective, they can be refurbished and redeployed in this manner.  I think that’s a great re-use of technology and existing (expensive) assets.  The transatlantic is the most heavily trafficked route in the world.  What we call an old cable in the transatlantic is a real new cable for a small island nation.  Pulling it off the seabed is not always easy.  If it’s there for decades, stuff tends to grow on it.  It’s a big job, but it is doable and it is being done.  I personally think it should be done increasingly going forward.