Debugging a network bug led a developer from Oxide Computer Company from oscilloscope traces to Wireshark analysis. The team was tracking a management network issue where some links failed intermittently. The root cause was a switch IC misconfiguration, but the investigation required deep physical layer analysis. QSGMII protocol decoding became essential for understanding the link between their VSC7448 switch and a PHY chip.

This protocol, packing four SGMII channels into a single high-speed pair, relies on 8b/10b encoding to ensure reliable data transmission. The developer extracted raw waveform data from an oscilloscope, parsed it into usable samples, and implemented a custom decoder to synchronize with comma characters marking code-group boundaries. This technical deep dive resolved the intermittent link problem, showcasing the practical application of low-level network debugging tools.