On December 10, at the 38th Chaos Communication Congress (38C3, essentially a German tech conference for various hackers and other community members), hacker Benjojo discussed how he had successfully pushed Toslink traffic, generally limited to 10 meters over 143 kilometers. Then, yesterday, fellow hacker Manawyrm demonstrated IP-over-Toslink based on what that demonstration proved [h/t Hackaday]. The speeds are...not incredible since this cable isn't meant for this, but that it's possible at all is still cool.
So, what made it all possible? Benjojo uploaded a full-text version of his 38C3 conference speech to his blog, including the full technical details of how Toslink was at such an unreasonable 140+ kilometers. This move, apparently an exercise in learning more about optical data transmission, involved more than just sending unconventional data. Toslink is typically restricted to just 10 meters but was eventually tested and pushed as far as 143.2 kilometers, albeit with lots of separate contraptions and data center involvement required.
Benjojo proved that optical data transmission is impressive, and its complex rules remain in play even when restricted to yesteryear technology like a Toslink optical audio cable. However, for the typical user, Toslink cables are impractical for use as last-resort fiber networking cables, particularly when the speeds are capped at roughly 1,536 kbit/s or just 0.19 MB/s.
Meanwhile, Manawyrm's IP over the Toslink hack, detailed on her KittenLabs page, reflects real-world IP transmission speeds of about 1.47 Mb/s, or 0.18 MB/s. This isn't quite the maximum limit of Toslink (about 3% short), but it's probably as close as we're getting.
Manawyrm and Benjojo have proved that most optical data cables do almost the same. With the correct tweaks, specifically designed cables like Toslink can be extended to distances and formats beyond what their creators ever imagined.
There's a lot of beauty in that, and the technical expertise required in its execution speaks volumes of the determination necessary to push technology to its limits. Unfortunately, it is still a Toslink cable at the end of the day, so there's no practical use beyond what Benjojo and Manawyrm learned by pushing Toslink to its limits. Actual networking cables aren't going anywhere anytime soon.
