On 12/23/2016 07:14 PM, Jeremy wrote:
Hi all,
First, i'm sorry for my english, i'm french and i don't have a good level in this language. But i want some informations and i'm sure, someone will be give the good anwser about my question.
So, i'm regarding to rent a dual dark fiber in France, the estimated distance is 225 Km, but i know there are a lot of optical switching on the highway where it's fiber is installed (in theory, all 80 Km). So, i used the bad scenario, in adding 25 Km on my need.
I would like to buy a amplificator and multiplexer DWDM to add some 10Gb/s waves on this dark fiber. I've see that the amplification is better on 100 Gb/s synchronised ports, but we don't have enoug capacity on our router to add 100 Gb/s interfaces.
So, someone has installed this type of hardware on a dark fiber without regeneration on 250 Km of distance ? If yes, with what kind of hardware ? If you are commercial for this hardware, please contact me in private message.
Look up Raman amplification. The short of what this does is it pumps a ton of power into the near end of the fiber span and creates what looks somewhat like a typical color-blind amplifier somewhere several dozen km out on the span. You'll also need to dump a ton of power into the span at the far end using an EDFA or similar. Even with both of those, that distance is still going to push the raw optical power budget of even most state-of-the-art transceivers especially if the fiber is old or of low quality (high loss, high dispersion, etc.). The longest span I've ever gotten a vendor to commit to an engineered design for was about 140km, and of course they needed full characterization of the span before they'd do it. At those distances, distance alone is no longer sufficient to throw together a design. It seems highly likely that there's at least one re-gen facility along that span. I'd definitely see if there is one and if you can get some space in it. That will knock you down into the 100-130km range on both sides of the re-gen, hopefully, which is perfectly doable. You are somewhat correct that 100Gb interfaces often handle longer distances better, but it's because they are often using coherent receivers and carrier-synchronous transmitters rather than raw power receivers and ASK pulsed transmitters. There are vendors that sell coherent 10Gb transceivers, too, and they'll be cheaper than 100Gb solutions especially if you don't need the extra capacity anyway. I'd definitely check them out for this type of application especially if you can't get any dispersion compensation in the middle since coherent optics are usually much more tolerant of chromatic dispersion. The big vendor I've worked with in the past on this sort of stuff is Ciena (and they're certainly a juggernaut in the industry) though I have no connection to them other than as a satisfied (if occasionally broke after a PO or out of breath after seeing a quotation) customer/integrator. -- Brandon Martin