https://cs.lozic.me/areas/networking/Recent content in Networking on CS TheoremsHugoen-usFri, 26 Feb 2027 12:00:00 +0100https://cs.lozic.me/posts/t021-the-noisy-channel-coding-theorem/Fri, 26 Feb 2027 12:00:00 +0100https://cs.lozic.me/posts/t021-the-noisy-channel-coding-theorem/<h2 id="symptom">Symptom</h2> <p>Your link drops 1% of bits. You need reliable delivery, so you triple every bit and take a majority vote. Now an error needs two of three bits to flip, which happens with probability about $3 \times 10^{-4}$ — better, but you paid 3x in bandwidth and the error rate is still not zero.</p>https://cs.lozic.me/posts/t061-the-two-generals-problem/Fri, 30 Oct 2026 12:00:00 +0100https://cs.lozic.me/posts/t061-the-two-generals-problem/<h2 id="symptom">Symptom</h2> <p>You call the payment API. The request goes out. Nothing comes back.</p> <p>Did the charge happen? You genuinely do not know. Retrying might double-charge the customer. Not retrying might drop the payment. There is no third option available, and no amount of care in your client library creates one.</p>https://cs.lozic.me/posts/t091-hyrums-law-and-postels-principle/Fri, 11 Sep 2026 12:00:00 +0200https://cs.lozic.me/posts/t091-hyrums-law-and-postels-principle/<h2 id="symptom">Symptom</h2> <p>You fix a typo in an error message. Four days later a customer escalates: their alerting pipeline greps for the old string and has gone quiet.</p> <p>Or you make a function faster, and a test suite that had been green for two years starts failing intermittently — not because the function is wrong, but because it used to be slow enough to hide a race.</p>