What's immediately obvious is the line is much faster than going over the public internet, and there's no jitter: every time you ping it comes back in the same amount of time, whereas the internet pings will vary by several ms.
You also become acutely aware of cable breaks. Somehow this happens quite often under the English Channel. The network operator will start sending you emails that say
- Cable break detected
- Loading ship (can take ages)
- Found the break
- Patched it
- Back up
Occasionally bad weather would delay it.
You're not lying. :) When the internet is down in the ROI (Republic of Ireland), it's always because something was dragging along the seabed and cut the cable[s].
Given that the ROI doesn't have many IX's for international connection[0,1,2], it's quite hard to miss when it does happen.
 - https://en.wikipedia.org/wiki/Internet_Neutral_Exchange
 - https://www.inex.ie/technical/network-diagram/
 - https://www.submarinecablemap.com/#/country/ireland
Is the short form (Republic of Ireland) ROI used often? Because the first thing that springs to mind reading ROI is Return of Investment.
Isn't Ireland short enough as a word? I understand there is Northern Ireland, but people will actually put Northern In front of it to be specific. Like North Korea instead of Korea.
It's a good way of easily differentiating between whether you're talking about Ireland the island, or Ireland the country, which currently excludes the six counties of Northern Ireland (NI) which are still part of the UK.
The term Ireland is often used to refer to the island as a whole, but obviously this can depend on the political leaning of who you're talking to.
Northern Ireland, depending on context and/or who is speaking can otherwise be referred to as Ulster (problematic, as the province of Ulster has 9 counties, only 6 of which are in Northern Ireland). It is also common in some circles to refer to the 6 counties currently occupied by the British simply as "the north".
In short, Ireland is a hot geopolitical mess and when talking about Ireland, it is useful to be as specific and as neutral as is possible.
So ROI/NI are quite useful shorthands.
Way closer than you think. (Using desire for a united Ireland as a proxy here)
Most often usages for me are filling out forms and that's often the shorthand representation next to the soccer team's score during a match.
It disambiguates the polity from the island, which includes both the Republic and a sometimes problematic piece of the United Kingdom.
You do have to be specific about what you mean when you say "Ireland" in any context where it is important that you are understood.
"Ireland" can quite correctly either mean the island of Ireland or the country called Ireland (aka The Republic of Ireland). In a political or business context you are likely to be specifically referencing one or the other.
"Off Topic: Is the short form (Republic of Ireland) ROI used often?"
But also no. Cables landing in ROI would be under completely different regulatory control to cables landing in NI which would be under United Kingdom regulatory control.
In other words, based on your assumption that "Ireland" is precise enough and since Belfast (NI) has it's own IX, that would mean that you would have dichotomy where "Ireland" could connect to the internet and "Ireland" could not, yeah?
No doubt there are a great many other parallel situations out there. My dental hygienist took issue with the Netherlands being called Holland.
Unless you were lighting that fiber yourself you were renting wavelengths and not the physical fiber.
>"What's immediately obvious is the line is much faster than going over the public internet, and there's no jitter: every time you ping it comes back in the same amount of time, whereas the internet pings will vary by several ms"
Jitter is caused by congestion which happens at router interfaces. The absence of jitter is not due to the use of dedicated submarine fiber spans per se as the speed of light in fiber is a constant. What you are likely seeing is the result of a network operator who has optimized for low and consistent latency by having fewer hops in their network before and after the cable landing stations.
Edit: Why the downvotes? Adjusting the price to how much the customer is ready to pay instead of just offering the cheapest possible price is usual business practice.
In a few weeks there is annindie film called The Hummingbird Project about avrace between firms to build the fastest dedicated trading line.
Apparently HFT's have moved on to microwave (https://www.bloomberg.com/news/features/2019-03-08/the-gazil...) to gain a further edge over fiber optic.
How often? Once or twice a year?
And what were the reason it breaking so often? I thought the English Channel were quite free of Cargo Ships and the like.
The English Channel is the busiest shipping lane in the world: https://www.youtube.com/watch?v=pzJwXxUY3MM
Very much not:
There is some discussion to be had as to whether there are other sections of water that are more active and have been for some years, but even if the channel isn't the busiest it is certainly very busy.
Further, I'd wager that initially buried cable in the Channel often is exposed on the bottom due to strong currents, rendering it more vulnerable - but this is just a guess, mind.
If the ship is ready it seems to take a day or so to get to the site. There's not always a ship though, not sure how it's organized.
Another day at the site and it's done. But any weather blows up the schedule seemingly.
I've never received anything other than emails about this so I'm not actually an expert.
Having seen internet connectivity in India slowly grow from only satellite-based connectivity, to having private internal interconnecting hubs within the country for bandwidth providers and ISPs to reduce latency, then news of every new submarine line improving bandwidth and latency, thereby reducing pricing. Going from getting 135ms - 200ms via dialup locally, to getting 60ms to Singapore and Hong Kong while playing Counter Strike and Quake 3. It was such a high!
Each development was so critical and it brought me great joy, and excitement. Still does!
Interesting to note that submarine cables played a significant part in the plot of Cryptonomicon by Neal Stephenson.
Indeed well worth a read even this long after it was published.
Cyrus Field's Big Dream: The Daring Effort to Lay the First Transatlantic Telegraph Cable
For a slightly wider take, Arthur C. Clarke's "How the world was one" is a most readable account of how telecommunications has made the world smaller, starting with the first submarine cables, proceeding with satellites (of course he would!) before devoting a section to fibre optics at the end. Brilliant account.
I did the tour a few year ago, run be retired engineer who was enthusiastic and excellent at explaining the difficulties in getting it all working.
As an added bonus, old school html:
Someone gave it to me at a previous job but never left a note to say who so I couldn't thank them.
(It's a expression, but I'm sure someone else will get it :) )
Can't tell you the number of times I've had someone insist that the internet was on satellites.
Using terms like "the cloud" and with everything bring wireless definitely doesnt help with people's misconceptions.
Even after I carefully explain that the internet uses under sea cables and generally either buried wires or above ground stuff I get dubious looks they say "yeah, right. You're probably just confused..."
It has to go to space!
How is that not automated? I cant believe that companies would rely on humans doing a boring and repetitive task without error for weeks on end when a single error could cause double digit percentage of time at port. Is this is just such an uncommon task that automating this wasnt worth the time saved at port?
edit: Even in the picture in the article you can see a single worker has removed their shoe covers that all the other employees are wearing. Doesnt that degrade the cable right there?
A supervisor comes over to me and says something like "I can see what you are thinking. There's no use - it is cheaper this way."
The point was that while the ship was in port taking on cable, it was fully manned anyway. Crews need something to do - so might as well stow cable.
That's our kit in the topside photos. Small world!
) We do all sorts of other things as well - relying on cable laying alone would be too much of a niche market!
The point was that while the ship was in port taking on
cable, it was fully manned anyway. Crews need something
to do - so might as well stow cable.
I am now curious; I'll fire off an email with a few questions to my liaison at TE SubCom. With any luck, answers arrive in time to be relevant to this thread.
I thought this was common knowledge until the first time I explained it, and the disbelief... Everyone had a revelation that day.
I always knew about fiber optics, growing up with dial up and dreaming of one day having a fiber connection. But I guess now that everyone is focused on mobile that piece of infrastructure is abstracted from even reasonably tech savvy people.
If it takes 1ms for the 1 bit to get to the other side, it’s still going to take 1ms for N bits to get to the other side, even N-multiplexed.
It’s the bandwidth that’s improved with multiplexing.
E.g. "how fast is your internet", etc.
It's of little value to the end user to know how fast a bit travels, all they care about is how fast they can download.
1) The cable still looks pretty thin, is it being housed in some sort of protective layer/tube before it is laid? Seems like an anchor snag could easily break that line. If that happens, is it possible to 'patch' a fiber cable?
2) Once it nears the coast, how deep is the line being buried?
3) This may be a dumb question (I'm no engineer), but does the light travel from the source all the way to end without any "relay" mechanism?
4) How much bandwidth can travel through one of these lines?
2) Depends, but a metre or two (tops!) would be the right ballpark.
3) Not a dumb question; while loss in fibre optic cable is very low, repeaters are installed at regular intervals along the cable. they are powered by high-voltage DC supplied through the cable armor. The ocean acts as the return path.
If nothing else, both ends still share a common ground reference, yeah?
Edit: thinking about this more, it seems quite obvious that you need a current return path regardless. If it's not the ocean/earth - what is it?
That's incorrect, amplification is done via Erbium doping, it is part of the core of the cable. There are no external repeaters.
I mostly work with land systems, where the EDFAs are pieces of equipment completely separated from the fiber - you get a normal strand of fiber dug into the ground, and once you want to amplify it, you've got to plug it into an EDFA line card with the erbium-doped fiber already contained in it.
In the sea, those systems are way more integrated and the fiber is usually spliced right into the amplifier.
I might be able to dig up a card tomorrow if you're curious as to how the system looks.
About the patching, they say that in the article: they sometimes cut the cable (in case of a bad weather) and attach it to a buoy. So they can "patch it" ;)
1) The fiber is pretty thin, but there are several fibers combined in one transoceanic cable, see here https://en.wikipedia.org/wiki/Submarine_communications_cable. They don't patch them, but splice the fibers. Patching introduces a little loss, so it should be avoided.
2) Not sure how deep they are buried, but I think to remember that the shore end of a submarine cable is better protected than the part in the deep ocean. Due to more ship traffic at the coast etc.
3) Good question. The loss of an optical fiber is roughly 0.2 dB/km. Across the ocean the optical signal must be amplified several times (every 80-100km). Nowadays the amplification is all optical (EDFA or Raman). Before there were electrical regeneration schemes. Check out the history of the field, it's is quite interesting .
4) Not sure how much data such a cable can carry, since it depends on how many fibers are deployed within. However, there are multiple interesting things to look into here. In research labs, people are investigating multicore/multimode fibers (space division multiplexing) , these fiber have incredible capacity. Personally, I think the most interesting metric is the spectral efficiency, so how much data can be transmitted per second per Herz. Such a metric is independent of multiplexing schemes over space/wavelength/time, and improvements have to come from better devices, signal processing or signal shaping methods . Another mind-blowing area is using the nonlinear Fourier transform for better signaling methods .
Feel free to ask more questions :)
and checkout the two biggest conferences for more in depth info.
 Multicore: https://ieeexplore.ieee.org/abstract/document/7341685
Salary-wise it's difficult for me to answer, as most of the big industry players are in the US or Canada, but I'm in Europe. From hearsay a fresh PhD with reasonable publication list will get around 10k per month in the bay area. However, glassdoor might give you a better idea. Look for companies like: Infinera/ciena/acacia communications/juniper/mellanox/finisar/keysight...
After my PhD, I probably could have pursued a postdoc somewhere in Europe, but I decided to leave academia. I wanted to stay in Copenhagen and therefore had to change my field of work and will be working for a hearing aid company in their signal processing department.
Surely they should be huge in valuation yet hidden away from the public glare.
You can follow Jean-Luc Vuillemin  on Twitter for very interesting pictures of ships laying cables around the world.
One of the largest undersea cables plant is Alcatel in Calais, France (Dover straits). The factory is linked to the port by huge tunnels under the city. Unfortunately the Wikipedia page is only available in french but contains nice pictures
Unless Jesus is one of the crew members, that isn't nearly enough.
Things not covered in this article:
Expected carrying capacity?
How much dark fiber (initially unused capacity)?
How much extra cable is required to make sure it stays on the bottom even when going over oceanic mountain ranges?
How much of the ocean-floor survey data is open, how much is proprietary, and how much is (military-style) secret?
Is there any sabotage?
Do nav charts warn about these things?
Edit: ah, from another comment down-thread: https://en.wikipedia.org/wiki/Operation_Ivy_Bells
I don't really understand this move. Surely the way that the Internet is designed, you can connect any network to any network. Why would this be any different with a physical cable in terms of security?
IIRC military and defect corps have separate cables installed for themselves, and the Russian’s were trying to read the signals.
Would someone tell more about it or add the Wikipedia page here please?
I should had clarified I am quite dim visaged about it.
That can literally mean GooFaceAma has better global performance than competitors. Or that competitors will be forced to get hosted on one of those cloud providers to get similar performance.
It makes me feel a bit worried that "the internet" is not as neutral as I would like it to be. (Or that I thought it was before)
I'm left wondering whether it's Amazon or Apple or both that own some of those cables.
The electromagnetic interference between cables is the reason why you shouldn't wire a house with data cables and power cables next to each other.
This is funny. Why “nearly”?