Salvaged Silicon: Building an Open Network OS for a Switch the Industry Left for Dead#

Christopher Wright – EdgeNOS / NOSaic

• Why: A genuinely free-and-open NOS for EOL Broadcom-based switches — probing what "open networking" should have meant, and architecturally interesting: the kernel FIB is the source of truth.
• What: EdgeNOS/NOSaic: a from-scratch NOS with no license or support contract, treating the box as an ordinary Linux router — routing daemons (FRR, static routes) program the kernel FIB, and a userspace agent (edged) mirrors it into the ASIC's tables; front ports are real netdevs so ip, ethtool, and tcpdump work unmodified; any daemon installing a kernel route gets hardware forwarding for free. Running on AS5610 (Trident+), AS4610 (Helix4), Arista 7050TX-64/SX2-72Q, Nexus 3172TQ; the Intel Fulcrum FM6000 currently forwards only by replaying a captured EOS boot trace. AI-assisted reverse engineering collapsed the register-bring-up problem (9 directions → 250+ actions → 115 live probes in one session).
• How: No vendor SDK — hardware state reconstructed from dumps of a known-good install; hard-won lessons include: copy-to-CPU is internally a multicast replication (no replication engine, no copy), stale status registers masquerade as dead hardware, and every optic needs switch-side code. ONIE installable, Linux 6.1 maintained into 2027 with A/B slots and auto-rollback.
• Where applicable: Hobbyist-origin but real; applies to the large category of abandoned Broadcom-era gear (~600 Broadcom device IDs). Not a supported production NOS today — its value is as a proof of the disaggregation model's unfinished half and a signal for open-NOS strategy.