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Repair Crews Reach Vicinity of Damaged Cables In Mediterranean
Posted by
timothy
on Tue Dec 23, 2008 12:40 PM
from the now-we-need-a-plucky-diver dept.
from the now-we-need-a-plucky-diver dept.
GWMAW writes "A robotic submarine searched beneath the Mediterranean on Sunday for damaged communications cables, two days after Web and telephone access was knocked out for much of the Middle East.
Telecommunication providers from Cairo to Dubai continued Sunday to scramble to reroute voice and data traffic through potentially costly detours in Asia and North America after the lines running under the Mediterranean Sea were damaged Friday." According to the article, "Once found, the cable ends will be pulled to the surface and repaired on deck — a process that could take several days."
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Mediterranean Undersea Cables Cut, Again 329 comments
miller60 writes "Three undersea cables in the Mediterranean Sea have failed within minutes of each other in an incident that is eerily similar to a series of cable cuts in the region in early 2008. The cable cuts are already causing serious service problems in the Middle East and Asia. See coverage at the Internet Storm Center, Data Center Knowledge and Bloomberg. The February 2008 cable cuts triggered rampant speculation about sabotage, but were later attributed to ships that dropped anchor in the wrong place."
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Dang! I was getting SUCH a good deal (Score:5, Funny)
Dang it! I was getting SUCH a good deal from the colocation facility in Yemen.
Wow (Score:5, Funny)
How do they do it? (Score:5, Interesting)
How do they repair the cables? Especially with glass fibre I wouldn't know what to do.
Re:How do they do it? (Score:5, Funny)
> How do they repair the cables?
Superglue and duct tape.
Parent
Re:How do they do it? (Score:5, Funny)
this is for UNDER WATER use.
therefore, its better left to DUCK tape.
(sorry....)
Parent
Re:How do they do it? (Score:5, Informative)
Luckily you can have both in one :)
http://duckproducts.com/products/detail.asp?catid=1&subid=1&plid=3 [duckproducts.com]
Parent
Re: (Score:3, Funny)
Surely not! We all know here that ducks float.
Re:How do they do it? (Score:5, Funny)
Surely not! We all know here that ducks float.
Only if they weigh the same as a witch!
Parent
Re: (Score:3, Funny)
Red Green [wikipedia.org] to the rescue!
Re: (Score:3, Interesting)
I'm sure it's possible to cut off clean ends and put a replacement between, possible install a repeater in between. The beam already has to be extremely powerful to cross hundreds of miles, another cut shouldn't cause too much attenuation.
I just hate to think what happens if this happens too many times, they'll have to lay a whole new cable.
Re: (Score:2)
Re: (Score:3, Insightful)
how do you propose to power it?
I'm not saying power couldn't be supplied, but I don't think it'd be cost effective, and you'd need to run a whole new set of lines.
Re: (Score:2)
Re:How do they do it? (Score:5, Informative)
Actually, there are repeaters in line, albeit I don't remember the distances. There's a big copper conductor in the jacket (just one, the ground is the ocean itself) sending a couple hundred volts through it.
Parent
Re:How do they do it? (Score:4, Informative)
how do you propose to power it?
I'm not saying power couldn't be supplied, but I don't think it'd be cost effective, and you'd need to run a whole new set of lines.
The same way the repeaters are already powered - the are power leads bundled with the fiber cable. In a full cut, they would have to repair the copper power leads anyway.
Parent
Re:How do they do it? (Score:5, Informative)
The actual fiber repair is done pretty much as it would be done for terrestrial cables. Either a fusion splice, usually by re-cleaving the ends for a clean surface and vibrating the ends ultrasonically to heat by friction and weld them together, or a very small splicing kit that holds the ends in near-perfect alignment, usually filled with a gel of identical optical properties to reduce the loss and refraction. Since space is an issue, I suspect fusion splices are the only acceptable option.
The biggest problem is both accomodating the repairs to the fiber jackets, and then re-sealing the cable. I wouldn't be suprised that there are fairly standard splice boxes that solve this.
Replacing segments doesn't seem like a good option. Any useful segment should measure miles in length, which is pretty expensive. Even replacing a segment and hauling the old one in for repair sounds like more trouble than it's worth. Of course, repairs on the open sea sound like fun to me. I had enough trouble sitting at a little worktable in a dim cable room with equipment balanced here and there, and testing going on constantly. A nice 20-30 foot sea would make me want to apply at the local McDonald's. Life is too short.
But nice work if you can do it.
Parent
Re:How do they do it? (Score:4, Informative)
Fusion splices are the only acceptable option because you can't afford to have a 0.1 dB splice on a long fiber. Too much loss will upset your whole link budget and you will not get an acceptable SNR at the far end.
BTW, I have never read how a fusion splicer works, but all the ones I have used align the fiber and look like they send a current between two metal contacts for ~0.2 seconds that fuse the fiber. I'm pretty sure ultrasound isn't used. When you are trying to align two fibers exactly, vibrating them doesn't sound like a good idea.
Parent
Re: (Score:3, Interesting)
But nice work if you can do it.
No it's not.
I dunno how things work on cable ships for other countries, but working on the USNS Zeus [fas.org] sucks bigtime.
No internet, no phones, no email, not even any outgoing traffic. NO electronic emissions of any kind. That also includes satellite TV because the dish does emanate some EMF. The only thing you can get is US Navy fleet broadcast coming in on UHF or EHF. You're gone for 3-4 months at a time, nobody onboard except for the captain knows where you're going or when
Re: (Score:3, Funny)
So, after a nudge, nudge you get a wink, wink? Does that make the cable a goer?
Re:How do they do it? (Score:5, Funny)
Don't worry, you don't have to do a thing. They already have people who do know what to do.
Parent
Re: (Score:2)
That is why you are not doing it.
I am not an expert myself. However Glass does Melt, and can be fused back together, is a possibility, or the ends polished and put right next to each other... Perhaps there is a lot of Dark Fiber built into the cable to be bypassed. Humans made the technology, they probably know how to fix it.
MacGuyver uses a Swiss Army Knife, and this: (Score:2)
http://en.wikipedia.org/wiki/USS_Jimmy_Carter_(SSN-23) [wikipedia.org]
Re:How do they do it? (Score:5, Informative)
How do they repair the cables? Especially with glass fibre I wouldn't know what to do.
My assumption would be that there are points built into the cable where you can exchange out bad segments for new segments.
Parent
Re:How do they do it? (Score:4, Informative)
http://www.laser2000.co.uk/fusion_splicers.php?area=262
Parent
Re: (Score:3, Funny)
Re: (Score:2, Interesting)
It would be interesting if they could build a cofferdam to house the bad ends and conduct repairs in it.
Say each segment is some 300 feet long. One or more cofferdams of such length could be built and kept on stand-by. When a cable is damaged or cut in some way, the cofferdams (maybe similar to a submarine or coffin with hinges on one side so that the other open and close to admit the cable. The bad ends would be trimmed off and given new ends, and the cofferdam unlocked and flooded and dragged aside, or th
Re: (Score:3, Interesting)
Re:How do they do it? (Score:5, Informative)
Optical Time Domain Reflectometer. You just ping the broken end and get a distance measurement.
Parent
Standard fare on good network testers (Score:3, Interesting)
I used to work at a network operations centre and we had testers that did all the kind of stuff. They'd tell you how long a cable was, what the loss was, if there was a break, info about the other end, etc, etc. Also could do layer 2 and 3 diagnostics. It was a real useful tool if a connection didn't work. Plug it in, see what looked out of place.
Re:How do they do it? (Score:5, Informative)
With a device known as an Optical Time Domain Reflectometer [wikipedia.org]. Supposedly they can not only detect cable length, breaks, but even the location of splices.
Parent
Re: (Score:2)
Well you can, in a way. A pulse of light will be partially reflected from the broken end and the round-trip time measured. You should also be able to detect the last repeater in each half and so isolate the break to segment between the repeaters. There is also copper wire in the cable to power the repeaters and it should be possible to figure out how far the break in it is from the shore station by several methods.
IMHO the operators need to give more thought to reliability. They need more space diversit
OTDR (Score:2)
http://en.wikipedia.org/wiki/Optical_time_domain_reflectometer [wikipedia.org]
Re: (Score:3, Informative)
Actually, you can. You use a device called a Time Domain Reflectometer [wikipedia.org], which sends a pulse down the line and times how long it takes a reflection to come back.
2 * Distance = Speed of light * Round trip time
To find the location of the fault to within ten feet you need a timer with about a 20 nanosecond resolution, which equates to a 50 MHz counter -- not too difficult.
Re:How do they do it? (Score:4, Informative)
fiber splicers - its mostly done in the field because in house we have handy-dandy prespliced fiber cables of different lengths. If you see (fill in local ILEC) out repairing a cut cable, chances are they might be splicing.
Parent
Re:How do they do it? (Score:5, Informative)
How do they repair the cables? Especially with glass fibre I wouldn't know what to do.
They drag the cable up and cut it (assuming it is not already in two pieces). They strip back the armor and sheath on both pieces. They then splice in a new piece of cable using a fusion splicer, which basically lines up each individual fiber (quite a time-consuming process to clean and prep each piece) and then the fusion splicer essentially melts the fiber strand back together. They put heat-shrink and something like a splint to keep it from bending over the spliced area and then fit each splice into a tray. The trays are then mounted into a splice case. Submarine cables are much more difficult because it has to be well sealed and able to withstand significant pressure.
The faults are located using an OTDR (Optical Time Delay Reflectometry), which basically sends light down the fiber and measures the reflections. As we know the speed of light we can accurately measure the distance to a break, imperfections, etc of the cable and splices.
Parent
Re: (Score:3, Informative)
They cut the cable in half, and put a new piece in it. They can locate the exact point of failure using an OTDR, as already mentioned in other comments by now.
In one such big under-sea cable, there could be hundreds of individual fibers inside. (It doesn't cost alot more to put another fibre in the big cable, and you get alot more bandwidth to sell).
For each fiber inside the cable they "weld" it to the new piece they are putting between. (I'm sorry, I don't have the correct translation for the word in Engli
Re: (Score:3, Insightful)
I'm wondering about the "pulled to the surface and repaired on deck" part.
I imagine a cable laying on the sea floor going more or less "straight"
from A to B. Is there enough slack in the line to bring the broken
ends to the surface and hold them together?
(Clearly, the answer must be 'yes'. But I'm just wondering if anyone knows
more about it. Do they intentionally leave in some slack just for such a
reason when they lay a cable like this?)
Slack (Score:3, Interesting)
Re: Slack (Score:5, Informative)
There was a terrific article written for Wired by Neal Stephenson (yes, that Neal Stephenson!) called Mother Earth Mother Board [wired.com] all about the laying of the longest underwater telephony cable in history. He goes into a lot of details as to how the cable is laid, what happens to the cable when it reaches shore, what is the cable made of, how does it work, etc.
Here's an excerpt where he explains how slack affects the process:
Parent
Conspiracy Theory (Score:2, Interesting)
If I was a certain US entity who is worried about more and more internet traffic avoiding the ol' USA, I'd "damage" a cable while using the outage as a cover to put a tap a few hundred miles away. If anything goes awry while tapping the cable, the obvious damage will be labeled as the cause.
But that's just me.
Not necessarily a single point of failure. (Score:2)
I don't think this is a single point of failure. Now, of course I didn't read the article, but according to this map [telegeography.com] of submarine communications cables, middle east has more than one cable reaching it.
cables and eavesdropping (Score:4, Funny)
I've got sources inside US intel that tell me these are botched attempts by Syrian intelligence to tap these undersea lines.
The chair is against the wall.
John has a long mustache. That is all.
Re: (Score:3, Funny)
... they will find Gilligan's Island and rescue the castaways.
And then whom ever owns the copy right to Gilligan's Island will misread the headline and sue them for using the under sea cable to download episodes of Gilligan's Island
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I bet 10$ that it's Gilligan who cut the cables by accident.
Gilligan Saved the Cable! (Score:3, Informative)
Re:Gilligan Saved the Cable! (Score:5, Funny)
Gilligan didn't cut the cable, ...
He gingerly buried it in Marianne's trench.
Parent
Re: (Score:2)
~500ms Latency.
Re:Satellites FTW? (Score:5, Interesting)
Yet another reason why we need a better satellite infrastructure. If everyone were using satellites, a reroute through Asia would be unnecessary.
Except for the whole "240ms minimum latency" thing. Also, it's a lot easier to fix a malfunctioning cable than a malfunctioning satellite. Also, bad weather over the Satellite NOC can take out everyone's connection.
Parent
Re: (Score:3, Informative)
Geosychronous orbit has too much time latency, and LEO takes more satellites to cover the same area. It'd be cheeper to just lay more cable, but corporations tend to push for raw efficiency rather than redundancy. It's going to take governments using their buying power to encourage redundant routes to get us back to where DARPA was in the '80s.