6 ms·
Petabit-class transmission over > 1000 km using standard 19-core optical fiber
- eqvinox 1y agoContrary to the "highlights" section (which seems to be the only place calling it a "standard" 19-core optical fiber), this is not in fact a 'standard' fiber, rather the origin seems to be the standard (125µm) diameter ("Sumitomo Electric was responsible for the design and manufacture of a coupled 19-core optical fiber with a standard cladding diameter (see Figure 1)"). Looks like the "diameter" simply got lost for the highlights section. (Nonetheless impressive, and multi-core fiber seems to be maturing as technology.)
- bcrl 1y agoInteresting work, but 19 cores is very much not standard. Multiples of 12 cores are the gold standard in the telecommunications industry. Ribbon fibre is typically 12, sometimes 24 fibres per ribbon, and high count cables these days are 864 cores or more using a more flexible ribbon structure that improves density while still using standard tooling.
- eqvinox 1y agoYou're confusing multi-core in a single cladding with multiple strands of cladding. This is 19 cores in a single cladded 125µm (which is quite impressive manufacturing from Sumitomo).
- bcrl 1y agoI wasn't confusing anything. To interoperate with industry standard fibre optic cables it should have a multiple of 12 or 24 cores, not the complete oddball number of 19. Yes it's cool that it's that small, but that is not the limiting factor in the deployment of long haul fibre optic telecommunications networks. Sumitomo sells a lot of fusion splicers at very high margins. It is in their best interest to introduce new types of fibre that requires customers to buy new and more expensive fusion splicers. Any fibre built in this way will need rotational alignment that the existing fusion splicers used in telecom do not do (they only align the cores horizontally, vertically and by the gap between the ends). Maybe they can build ribbon fibres that have the required alignment provided by the structure of the ribbon, but I think that is unlikely. Given that it does not interoperate with any existing cables or splicers, the only place this kind of cable is likely to see deployment in the near term is in undersea cables where the cost of the glass is completely insignificant compared to everything that goes around it and the increased capacity is useful. Terrestrial telecom networks just aren't under the kind of pressure needed to justify the incompatibility with existing fibre optic cables. Data centers are another possibility when they can figure out how to produce the optics at a reasonable cost.
- eqvinox 1y agoIt's impossible for this to interoperate with "normal" fiber, this is "coupled-core" fiber: the cores don't operate independently and a MIMO style setup like the paper describes is really the only thing you can do. Additionally, the setup uses optical amplifiers in 86.1km steps. Both of these things put this squarely in submarine-cable-only space. Total cable size is in fact a problem in that space, 4-core claddings are roughly state of the art there, but there's enough room for those to be non-coupled. Higher core counts requires research like this. Either way you'd be terminating a 19-core setup like this with an OEO (and probably FlexE and/or an OTN solution) both ends.
- ksec 1y agoThe actual figures are 1,808 km. For reference US is 2,800 miles (4,500 km) wide from east to west, and 1,650 miles (2,660 km) from north to south.
- exabrial 1y agoFor us Americans, thats about 295,680 toilet paper rolls or 2,956 KDC (kilo donkey kicks).
- aDfbrtVt 1y agoAs others have mentioned, this is mostly a proof of concept for a high core count weakly-coupled fibre from Sumitomo. I also want to highlight the use of a 19 channels MIMO receiver structure which is completely impractical. The linked article also fails to mention a figure for MIMO gain.
- eqvinox 1y agoWorse, it's offline MIMO processing! ;D I would guesstimate that if you try to run it live, the receiver [or rather its DSPs] would consume >100W of power, maybe even >1000W. (These things evolve & improve though.) (Also, a kilowatt for the receiver is entirely acceptable for a submarine cable.)
- aDfbrtVt 1y agoTo get a ballpark power usage, we can look at comparable (for some definition thereof) commercial offerings. Take a public datasheet from Arista[1], they quote 16W typical for a 400Gbps module for 120km of reach. You would need 2500 modems at 16W (38kW) jointly decoding (i.e. very close together) to process this data rate. GPU compute has really pushed the boundaries on thermal management, but this would be far more thermally dense. [1] https://www.arista.com/assets/data/pdf/Datasheets/400ZR_DCI_Solution_Datasheet.pdf https://www.arista.com/assets/data/pdf/Datasheets/400ZR_DCI_...
- eqvinox 1y agoI think the scaling parameters are a bit different here since the primary concern is the DSP power processing and correlating for MIMO 19 signals simultaneously. But the 16W figure for a 120km 400Gbps module includes a high-powered¹ transmitter amplifier & laser, as well as receive amplifiers on top of the DSP. My estimate is based on O(n²) scaling for 19×19 MIMO (=361) and then assuming 2≈3W of DSP power per unit factor. [but now that I think about it… I think my estimate is indeed too low; I was assuming commonplace transceivers for the unit factor, i.e. ≤1Tb; but a petabit on 19 cores is still 53Tb per core…] ¹ note the setup in this paper has separate amplifiers in 86.1km steps, so the transmitter doesn't need to be particularly high powered.
- throw0101c 1y agoThe NANOG has had a regular presentation by Richard Steenbergen called "Everything You Always Wanted to Know About Optical Networking – But Were Afraid to Ask"; last year's: * https://www.youtube.com/watch?v=Y-MfLsnqluM https://www.youtube.com/watch?v=Y-MfLsnqluM
- exabrial 1y agoAlright, I have a dumb question... How come with a LAG group on ethernet, I can get "more total bandwidth", but any single TCP flow is limited to the max speed of one of the LAG Components (gigabit lets say), but then these guys are somehow combining multiple fibers into an overall faster stream? What gives? Even round robin mode on LAG groups doesn't do that. What are they doing differently and why can't we do that?
- bradfitz 1y agoBecause your switch is mapping a 4 tuple to a certain link and these people aren't, is my guess.
- eqvinox 1y ago> What are they doing differently and why can't we do that? You're (incorrectly) assuming they're doing Ethernet/IP in that test setup. They aren't (this is implied by the results section discussing various FEC, which is below even Ethernet framing), so it's just a petabit of raw layer 1 bandwidth.
- cycomanic 1y agoIt's also important to note that many optical links don't use ethernet as a protocol either (SDH/SONET are the common ones), although this is changing more and more.
- Keyframe 1y agowhile fascinating I'm still waiting for that transformative move from electrical. Whichever optical route you're taking, at the beginning and at the end of it has to be an electrical conversion which hinders speed, consumes power and produces (sometimes tons of) heat. Wen optical switching?
- aaron695 1y ago[dead]