Two hackers have successfully extended the communication range of Toslink fiber optic audio cables, enabling unprecedented data transmission distances. While practical applications may be limited, their efforts could pave the way for future advances in optical data transmission and networking technology. Their ingenuity embodies the hacker spirit: constantly questioning, exploring and challenging the limits of what technology can achieve.
Two hackers pushed the limits of optical data transmission, proving that even outdated technology can be repurposed in unexpected ways. At the 38th Chaos Communications Conference (38C3) in Germany, known for attracting technology enthusiasts and hackers, Benjojo presented his work on scaling Toslink traffic well beyond its intended scope.
Toslink is an optical fiber connection mainly used for audio transmission, and its transmission distance is usually limited to about 10 meters. However, Benjojo's experiment extended this distance to an astonishing 143 kilometers.
Building on Benjojo's work, another hacker known as Manawyrm took the concept one step further. Just one day after Benjojo's presentation, Manawyrm demonstrated transmitting IP data over Toslink, effectively using audio cables to create a basic fiber optic network.
Benjojo's experiments involve complex data center equipment setups and various devices to achieve extended range. These include small form-factor pluggable (SFP) ports, Toslink analog-to-digital and digital-to-analog converters, and oscilloscopes.
The long-distance test connected two data centers in London's Docklands - Telehouse North and IP House - which are approximately 650 meters apart. The setup also utilizes fiber pairs connecting the data centers, a CWDM multiplexer to maximize fiber connections between buildings, and a fiber loop installed at the telehouse end to allow testing from a single location. Benjojo documented the entire process in a detailed blog post and YouTube video.
While the speeds achieved are nowhere near comparable to modern networking standards, the proof of concept is significant. The actual transmission speed of Manawyrm's IP-over-Toslink after modification is about 1.47Mb/s (0.18MB/s), which is slightly lower than Toslink's maximum theoretical limit.
It's important to note that these experiments don't herald a revolution in network technology. The maximum transfer rate of Toslink cable is approximately 1536kbit/s (0.19MB/s), making the speeds achieved impractical for modern data transfer needs.
However, these experiments highlight an important principle: With appropriate modifications, cables designed for a specific purpose can be used for purposes far beyond their original purpose. This flexibility in optical data transmission could inspire new ways of building networks in unconventional environments.
While these Toslink experiments are unlikely to replace traditional network cables, they highlight the potential for innovation hidden in seemingly outdated technology.