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Noise ripped out after the bench verdict (tightly-wrapped unshielded cables move victim SNR only 0.2-0.3 dB, recorded in measurement.md dead ends): noise.go deleted with the noiser, phase clock and panel lane; configureNoise/checkPrivFlag gone so the X710 pair is untouched; console noise column, NOISE links rows and lane colors removed; driverPair rehomed to system.go, carrierUp to phy.go; history anchors to run start (frame-rate sampling and draw-clock roll kept — they fix display latency for every lane); goals/hardware/state/nics docs updated; verified on hardware (20.00G, zero errors, ECD 41m, SNR +7.6)

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flamingcow
2026-08-17 21:37:18 -07:00
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docs/goals.md
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@@ -7,10 +7,11 @@ The target of measurement is the cable, not throughput. Line rate is a means to
## Outputs, in priority order
1. **Loss and error attribution** — reception gaps, link errors, NIC/driver counters as first-class output alongside application loss. Baseline loss must be exactly zero before a run counts; any host-side loss masks real cable faults.
2. **Noise tolerance** — a deliberately-bad "noise" cable intertwined with the test cable, driven by link up/down cycling, stresses the cable under test with alien crosstalk.
3. **Per-pair SNR** from the module PHYs — the leading indicator of a marginal cable before it drops frames. IEEE 802.3an standard registers on the Marvells; the BCM leaves those unpopulated and reports through its vendor command handler instead (modules/fs/). Shown as margin over the operating point, classified good/marginal/bad, so nobody needs the magic numbers to read it (`phy.go`).
4. **Cable length** — sanity check and fault localization. The BCM ECD is the product path: per-pair lengths in meters, healthy pairs included, proven meter-accurate on the bench (modules/fs/); run at bringup and on every reset, with pair-swap and fault verdicts on the panel.
5. **Pre-FEC error visibility** — corrected-error counters that move before post-FEC loss appears. Vendor-specific; located on the Aquantia (modules/fibergaga/), unlocated elsewhere. Standard latched PCS counters (errored blocks, BER, block-lock loss) are the working proxy under noise stress.
2. **Per-pair SNR** from the module PHYs — the leading indicator of a marginal cable before it drops frames. IEEE 802.3an standard registers on the Marvells; the BCM leaves those unpopulated and reports through its vendor command handler instead (modules/fs/). Shown as margin over the operating point, classified good/marginal/bad, so nobody needs the magic numbers to read it (`phy.go`).
3. **Cable length** — sanity check and fault localization. The BCM ECD is the product path: per-pair lengths in meters, healthy pairs included, proven meter-accurate on the bench (modules/fs/); run at bringup and on every reset, with pair-swap and fault verdicts on the panel.
4. **Pre-FEC error visibility** — corrected-error counters that move before post-FEC loss appears. Vendor-specific; located on the Aquantia (modules/fibergaga/), unlocated elsewhere. Standard latched PCS counters (errored blocks, BER, block-lock loss) are the working proxy.
Alien-crosstalk noise injection was an output here and is measured out (measurement.md, "Dead ends"): an intertwined noise cable moves the victim's SNR margin only 0.2–0.3 dB.
## Design preferences that shaped the tool