[HN Gopher] IP over Lasers
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IP over Lasers
Author : xtoilette
Score : 118 points
Date : 2025-09-29 16:19 UTC (3 days ago)
(HTM) web link (www.mikekohn.net)
(TXT) w3m dump (www.mikekohn.net)
| tgma wrote:
| Aren't regular fiber-optics just mass-deployed IP over lasers?
| (this message is brought to you by at least one, likely multiple,
| lasers in prod)
| advisedwang wrote:
| Yeah, but kinda cool making it from scratch.
|
| Also this uses air as the medium.
| jonah-archive wrote:
| Free-space optical transmission is a thing, though it's
| environmentally quite challenging. We tested some gear from
| https://www.koruza.net at the Internet Archive ~10 years ago
| or so (I've also built some 10G point-to-point links in my
| garage, though I'd hardly call them reliable). It is pretty
| cool to see a scratch build rather than using commercial
| transceivers
| tgma wrote:
| Doesn't Starlink do that already for sat2sat comms?
| eqvinox wrote:
| Not quite the same thing as doing it in an atmosphere.
| aerostable_slug wrote:
| That's right, the beam pointing problem is far harder
| when everything is moving.
| eqvinox wrote:
| There's this thing called wind that can move your outdoor
| installations quite a bit ;)
|
| I'd call it a wash, space is hard, but so are atmospheric
| interactions, weather, foliage, and all the side effects
| of human habitation (like someone building a house in the
| middle of your laser link, yes that happens.)
| littlestymaar wrote:
| Deterministic space dynamics vs chaotic fluid dynamics
| (or worse, as the sibling comment by eqvinox
| illustrates).
|
| Space is hard by many aspects, but on that part it's much
| easier than on earth.
| oskarkk wrote:
| Space dynamics are not that much deterministic. Gravity
| itself is kinda noisy (Earth isn't an ideal sphere with
| uniform density), there's the Moon, orbital decay (caused
| by drag from particles in low orbit, which is variable),
| solar radiation pressure (also variable), etc.
| Calculation of the dynamics will only give an approximate
| result, a prediction. They need constant measurement of
| the trajectories and frequent correction maneuvers (by
| ion engines). But yeah, I think that once the satellites
| accurately know each others trajectory, their movement
| shouldn't be a big issue for the lasers, as in the
| timespan of one laser connection it should be predictable
| with the required precision. And if both satellites would
| be on the same orbit, their relative movement should be
| ~0, so the laser beam ideally wouldn't move at all from
| the satellite's perspective, the angle would be constant.
| connicpu wrote:
| Starlink sats do fly just low enough that they experience
| some mild atmospheric drag. Their next generation sats
| will fly even lower too. But it's certainly still in the
| range where simple computer models will be very accurate
| for at least a few hours out.
| GJim wrote:
| Bizarre take.
|
| Atmospheric scintillation is the barrier for free space
| laser communications on terra-firma; this is one reason
| we enclose the laser light in optical fibre to avoid this
| problem.
|
| In space where _nobody can hear you scream_ ,
| scintillation isn't a problem.
| jonah-archive wrote:
| There's not a huge amount of info I've seen on the
| specifics of Starlink's LISL setup, but there are a
| couple interesting bits in here:
| https://www.pcmag.com/news/starlinks-laser-system-is-
| beaming...
|
| > Brashears also said Starlink's laser system was able to
| connect two satellites over 5,400 kilometers (3,355
| miles) apart. The link was so long "it cut down through
| the atmosphere, all the way down to 30 kilometers above
| the surface of the Earth," he said, before the connection
| broke.
|
| (the presentation that's being reported on, which I don't
| have access to:
| https://www.spiedigitallibrary.org/conference-
| proceedings-of... )
| pixl97 wrote:
| 30k would be about 1/3rd MSL air pressure, so that's
| pretty thin relative to what humanity experiences. Also
| note it says 'connection broke', not that the connection
| was way way slower than it would be in a vacuum.
| esseph wrote:
| Taara is a Google/X moonshot that was recently spun off to
| do the same thing.
|
| https://www.taaraconnect.com/product
| satiated_grue wrote:
| About 25-30 years ago we had an FDDI network, and the hosts
| had optical bypass switches on them.
|
| The FDDI network comprised two fiber rings, one going
| clockwise and the other anticlockwise. If a host dropped off
| the network, the optical bypass switch would loop the two
| rings to each other, creating one big ring. Two non-adjacent
| hosts dropping off the network would break the ring.
|
| The optical bypass was surprisingly simple. It was a couple
| of pieces of fiber segment glued to a swiveling magnet; an
| adjacent electromagnet pull the magnet/fiber assembly,
| connecting the network rings normally if energized. If power
| were removed from the electromagnet, a spring would pull it
| in the other direction, pointing the fibers into loop
| position, connecting the network rings in looped
| configuration.
|
| In both cases, the air was the medium between the fibers
| entering the switch and the straight-through/loopback fiber
| segments.
|
| Apologies in advance for my poor explanation.
| tgma wrote:
| Check out relatively recent Google TPU paper where they
| used an optical switch to connect neighboring TPUs
|
| https://arxiv.org/pdf/2304.01433
| bobmcnamara wrote:
| I'd assume most are LEDs or VCSELs. The long range stuff is
| laser.
| qwezxcrty wrote:
| VCSELs are lasers.
| SAI_Peregrinus wrote:
| The L in VCSEL is LASER.
| bobmcnamara wrote:
| Oh yeah!
| lifestyleguru wrote:
| Now try IP over electricity.
| a3w wrote:
| Photons vs electrons? Just rotate 90 degrees, seem to be
| swappable more easily than using neutrons or other particles,
| like tau/muon/electron neutrinos.
|
| Oh wait, didn't fermilab even use neutrinos in 2012? That seems
| even harder, practically made for an April fools RFC.
| proxysna wrote:
| Powerline is sort of like that. Devices act like an L2
| transparent proxies over electrical wiring.
| aerostable_slug wrote:
| Fun fact: large transmission lines use power line carrier
| communications for things like remedial action schemes and
| other system protection functionality (e.g. protective relay
| trip signals). The carrier can be a few hundred kV, so it
| tends to be outside the comfort zone of most casual
| experimenters.
| cestith wrote:
| I have UTP and DAC cables here at home. I even have a bit of
| 10base2 around here, although none of it's running at the
| moment.
| cortesoft wrote:
| IP over Lasers: Fiber optics
|
| IP over electricity: Ethernet
| toast0 wrote:
| Most IP over Lasers these days is Ethernet (although
| certainly other standards exist) 802.3ae covers a lot of 10G
| laser based ethernet over fiber for example.
| a3w wrote:
| A typical computer is connected to the local network using either
| an Ethernet cable or WiFi. This project connects two computers
| together through lasers.
|
| No mention of carrier pigeon? IPoAC has three RFCs!
| munchlax wrote:
| I'd not expect that to be "typical", unless you're in the
| middle of some pretty huge nature reserve and still need to
| file taxes online.
| alberth wrote:
| Isn't fiber broadband exactly this?
|
| It's shooting a laser through a fiber optic cable.
| proxysna wrote:
| Really like seeing networks over whatever laser things. Very cool
| stuff. This thing always comes to mind.
| http://images.twibright.com/tns/1208.html
| jasonjayr wrote:
| They built a program they called (relay) that sends packets
| between a tun network device & a uart serial device
|
| https://github.com/mikeakohn/small_projects/blob/main/ip_ove...
|
| I .... wonder if they considered just using PPP/SLIP?
| Retr0id wrote:
| A while back I was doing some IP-over-UART shenanigans and it
| took me a surprising amount of research to discover the
| existence of SLIP. I think it's one of those things that at
| some point "everyone knew about" and ended up being poorly
| documented as a result.
| wolrah wrote:
| SLIP is old and mostly forgotten for sure, but PPP was almost
| universal in dialup and unfortunately common in DSL. PPPoE
| was the bane of my existence as someone who had to support
| third-party routers on DSL. PPTP was also very common for
| small VPNs even well past when it should have been retired
| due to insecurity because it worked out of the box on Windows
| and Mac without a third party client.
| RossBencina wrote:
| Mid-90s you definitely had to know about SLIP to get your
| Linux or NeXT boxen to connect to your ISP.
| iberator wrote:
| CSLIP is even better.
| Atomic_Torrfisk wrote:
| Hahah, I slipped down that rabbit hole about 2 years ago. We
| needed network access for testing devices on one of our
| production lines, but the manufacture did not allow wifi at
| the time. So we ended up tunneling over UART to access
| internal APIs on the device. It worked fairly well, and was
| even able to load more complex customer facing react based
| UIs.
| apercu wrote:
| Generational thing. Back when I was supporting banks of USR
| 28.8s, SLIP and especially PPP were just the job (mostly PPP
| by that point).
|
| But even then I don't think I'd have thought to drag a dial-
| up framing protocol into a new project. Odds are I'd just
| recreate SLIP from muscle memory.... maybe?
| immibis wrote:
| I wouldn't be surprised if they were trying to remove them from
| the kernel since you can use a tun interface instead. They
| would be very good candidates for moving kernel functionality
| to userspace.
| toast0 wrote:
| Back when 10M ethernet was popular, it was pretty easy to wire up
| something like this with the transceiver (AUI) port... wire the
| tx to a laser and the rx to a photodiode (or whatever), ???,
| profit.
|
| There's lots of commercial equipment in this space too.
| eqvinox wrote:
| https://ronja.twibright.com/
| riedel wrote:
| When I studied our dorm was connected to the campus network via
| a laser uplink (and the Internet, with each room having a
| public IP address). I still remember the foggy daya when
| people, you normally did not see, gathered in the bars, because
| the network went unbearably slow. It was nice days with every
| CS student having a server rack in their closet. I had a VT520
| hooked up to it be able to read emails and IRC chats bed
| without having to wait for my PC to boot.
| supportengineer wrote:
| Has to be the early to mid 1990's?
| johncalvinyoung wrote:
| I was going to say, sounds like my college experience
| decades later. Still a very congested laser link, and I had
| a headless minitower instead of a rack (though I wasn't a
| CS student).
| teeray wrote:
| I dreamed of doing something like this growing up so that my
| neighbor and I could play StarCraft without the latency of
| dialup. I wish I knew then that it was that straightforward.
| MisterTea wrote:
| The AT tiny is not needed at all. You have a digital signal
| coming right out of the serial cable which can drive the laser
| using a buffer and a Schmitt trigger on the receiver.
|
| Eliminating crosstalk is the tough part and requires some
| modulation to ensure the transceiver isn't accidentally listening
| to itself via reflections or picking up interference.
|
| Look up point to point laser links. They have been around for
| quite some time.
| cuttothechase wrote:
| Isn't this just fiber optics! Exciting turn of the century tech
| hitting HN boards in 2025
| rafale wrote:
| Every year new engineers and enthusiasts need to be exposed to
| cutting edge technologies through hands-on introductions like
| these.
| kej wrote:
| I don't know why, but I would have expected higher speeds. Maybe
| my mind just assumes "lasers = fast". It would be interesting to
| know which factors make this setup unreliable at higher speeds.
| treve wrote:
| Individual bits always go fast, the difficulty is always
| telling many apart. Speed is kind of the wrong word. It's about
| throughput
| Sesse__ wrote:
| Most likely one of: 1. Noise in the detection
| (the room is bright etc.) 2. The laser being a form
| that's not susceptible to direct modulation (if it takes a
| millisecond to start/stop lasing, obviously you cannot turn it
| on/off very fast)
|
| High-speed laser-based systems (gigabit and beyond) don't try
| to turn the laser on/off at all, they just have something in
| front that tries to cancel out the signal (e.g., through self-
| interference) when you want to send a zero.
| zokier wrote:
| I would bet that the laser pointers used here are the
| bottleneck.
| NoiseBert69 wrote:
| We had a laser link to the university 20 years ago. 10MBit/s for
| 300 people.
|
| That thing was awful.. lol.
|
| The link was dead during
|
| - Heavy rain
|
| - Fog in the early morning
|
| - While snowing for days
|
| - Pigeons building a nest within the optics
| chasil wrote:
| There are many long-range WiFi solutions. I wonder how these
| would have performed as alternatives.
|
| https://en.wikipedia.org/wiki/Long-range_Wi-Fi
| NoiseBert69 wrote:
| Nowadays you just can buy pair of cheap Mikrotik oder
| Ubiquiti directional dishes.
|
| Back then this was rocket science.
| beAbU wrote:
| Google "pringles cantenna" to get an idea of what state-of-
| the-art long range wi-fi gear was like in 2005...
| chasil wrote:
| Yes, these were Yagi antennas.
|
| EBay has many models.
| blacksmith_tb wrote:
| Scale it up, and you have Taara[1]
|
| 1: https://x.company/projects/taara/
| psnehanshu wrote:
| I was vibe researching TUN/TAP devices a few days ago. Cool to
| see such cool projects using them. I was mostly thinking about
| making a VPN prototype through.
| esseph wrote:
| There's a billion different types of VPN.
|
| What problem are you trying to solve?
| psnehanshu wrote:
| Increase my understanding
| ggm wrote:
| We know neolithic internet used free air lasers because we
| haven't found either optical fibre connectors or copper Ethernet
| in the trenches we dig at neolithic settlements.
| sigmoid10 wrote:
| Is this a jab at the people who believe Egyptians must have
| used electric lights because we can't figure out how they lit
| and ventilated their tombs at the same time during
| construction?
| ggm wrote:
| It's a version of an englishman/irishman/Russian archeologist
| joke, one finds shards of glass (proves invented optics) one
| finds copper wire (ethernet) and one finds nothing (wifi,
| punchline)
| sigmoid10 wrote:
| Never heard this one
| Lerc wrote:
| I have always wanted to give this a try. I have this daft idea of
| implenting a system logically as an n-dimensional cube and
| physically on two facing surfaces (even and odd parity processor
| addresses) with laser connections between the processors. Perhaps
| it'll be one of my crazy project ideas that I can do in my
| retirement
| vin92997 wrote:
| I want to see the actual laser beams while transmitting those
| packets.
| CableNinja wrote:
| Do not look at the laser, you wont be able to look at it again
| lifestyleguru wrote:
| I met many people who after grabbing laser pointer first
| thing they do is pointing it into the eyes of a nearby
| person, from all the things they could point it to.
| devilbunny wrote:
| I always liked "Do not look at laser with remaining eye".
| lambdaone wrote:
| None of this is remotely new or interesting. I was doing IP-over-
| laser-light at Ethernet speeds over kilometer distances using
| free-space optics thirty years ago, and even then it wasn't a new
| technology.
| mschuster91 wrote:
| It's interesting for a hobby tinkering project. Basically like
| rudimentary transmitters for ham radio. Understand the
| fundamentals, then you can move on to better quality DIYs
| rnhmjoj wrote:
| Was that RONJA [1]?
|
| [1]: http://ronja.twibright.com/about.php
| beAbU wrote:
| Thank you for your valuable contribution to this conversation.
| nullbyte808 wrote:
| Why is the ping worse than connecting to a remote shack in
| Mongolia?
| voidUpdate wrote:
| I remember trying to my own data transmission over lasers ages
| ago, back when I didn't really know about how to properly
| transfer data (PLLs, clock recovery, error correction, etc). It
| lost timing pretty quickly, but it could just about do a hello
| world
| beAbU wrote:
| When I was about 10-12 for a school science fair I built a device
| called a "photophone" [1] - one of Bell's lesser known
| inventions.
|
| Basically, a filament flashlight is modified so that a magnetic
| coil was placed in series. An audio source is then fed through a
| second coil -- I can't remember the exact details of how this
| worked. The audio source was one of those fisher price sing-along
| tape players that I also modified I think. The tape was Abba.
|
| On the other end, a cheapo solar cell was hooked up to a small
| kit amplifier and then you could hear the audio on a pair of
| headphones.
|
| This was in 2002 ish, so fibre optics was a thing, but it was
| basically sci-fi for a scrappy kid in southern Africa. My whole
| spiel was how this was the precursor to fibre optics, and how one
| day all communications will be done using light in stead of
| electrons.
|
| Fun times!
|
| [1] - https://en.wikipedia.org/wiki/Photophone [2] -
| https://www.youtube.com/watch?v=SxlWrqioifg
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