21-EFT.WP.Metrology.Sync v1.0 | Chapter 1 — Synchronization Domain: Definition & Scope

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Chapter 1 — Synchronization Domain: Definition & Scope

One-line objective: Define the objects, boundaries, inputs/outputs, and publication gauges of network time–frequency synchronization so that offset/skew/J, TIE/MTIE, and the dual-form arrival-time conventions are comparable and auditable across systems.

I. Scope & Objects

1. Objects
   • Packet-network time/frequency synchronization (NTP/PTP/SyncE/White Rabbit), including master/slave clocks, Boundary Clocks (BC), Transparent Clocks (TC), and GM election.
   • Two-way packet timing {t1,t2,t3,t4}, link residence residence_time and correctionField, and physical/logical asymmetry asym.
   • Servo & holdover: PLL/FLL, sliding-window estimators, and robust filtering.
   • Stability gauges: TIE(t), MTIE(tau), tdev(tau).
2. Inputs
   • Timestamps & metadata: {t1,t2,t3,t4, correctionField, residence_time, port_role}.
   • Reference context: gm_id, domain, topology, target loop bandwidth H(f), tau_mono windowing.
   • Arrival-time dependencies: n_eff, c_ref, path parameterization gamma(ell).
3. Outputs
   • Estimators: offset, skew, J, TIE/MTIE/tdev, each with uncertainty U = k * u_c.
   • Servo quantities: loop.{Kp, Ki}, filter.scheme, state.
   • Release assets: manifest.sync.*, contracts.*, TraceID and signature.
4. Boundaries / non-goals
   No hardware register detail or PHY modulation coverage; does not replace protocol standards.

II. Terms & Variables

• Time & bases: tau_mono (internal monotonic base), ts (published timestamps), offset (master–slave phase), skew (frequency offset), J (aggregate jitter).
• Packets & links: t1..t4, correctionField, residence_time, asym (uni/bi-directional delay asymmetry), delay (RTT/one-way).
• Stability & spectra: TIE(t), MTIE(tau), tdev(tau), input noise PSD S_in(f), closed-loop transfer H(f).
• Dual-form arrival: T_arr = ( 1 / c_ref ) * ( ∫ n_eff d ell ) and T_arr = ( ∫ ( n_eff / c_ref ) d ell ), difference delta_form.
• Metrology gauges: unit(x), dim(x), check_dim(expr).

*III. Axioms P601- **

• P601-1 (Timestamp trust): Prefer hardware timestamps; when software timestamps are used, publish additional u(ts) and the compensation model.
• P601-2 (Explicit asymmetry): Do not assume symmetry by default; asym must be calibrated or online-estimated with a declared validity interval.
• P601-3 (Dual-form in parallel): Any synchronization or estimation involving arrivals must compute both forms and record delta_form.
• P601-4 (Unified time base): Compute statistics on tau_mono, publish on ts with U for offset/skew/J.
• P601-5 (Dimensional integrity): Run check_dim before publication; unit(offset)="s", unit(skew)="1" (or "ppb"), unit(J)="s".
• P601-6 (Traceable & signed): Attach TraceID, hash_sha256(blob), and signature to all results.

*IV. Minimal Equations S601- **

• S601-1 (Two-way offset & delay)
  offset = ( (t2 - t1) - (t4 - t3) - asym ) / 2。
  delay_rt = ( (t2 - t1) + (t4 - t3) - 2 * asym ) / 2 - correctionField - residence_time。
• S601-2 (Frequency offset / slope)
  skew = d( offset ) / dt，discrete approximation skew[k] = ( offset[k] - offset[k-1] ) / Delta_t。
• S601-3 (Jitter aggregation)
  J = rms( offset - lowpass(offset, BW) ) (explicitly publish the window and BW).
• S601-4 (Stability)
  TIE(t) = phi(t) - phi(0)；MTIE(tau) = max_over_t ( sup_window | TIE(t+tau) - TIE(t) | )。
• S601-5 (Servo output variance)
  var_out = ( ∫ | H(f) |^2 * S_in(f) df )，record the loop bandwidth and pole–zero scheme of H(f).
• S601-6 (Dual-form arrival difference)
  delta_form = | ( 1 / c_ref ) * ( ∫ n_eff d ell ) - ( ∫ ( n_eff / c_ref ) d ell ) |。

V. Metrology Flow M60-1 (End-to-End Loop)

• Ready — ingest {t1..t4, correctionField, residence_time}, topology and gm_id; load asym calibration or initialize online estimation.
• Cleaning — align to tau_mono; handle anomalies/duplicates; run dimensional checks; compute both arrival forms.
• Estimation — compute offset/skew/J, TIE/MTIE/tdev, and uncertainties U.
• Servo — configure H(f) targets and derive Kp/Ki & filtering; evaluate var_out.
• Audit — apply C60-* contracts; emit manifest.sync.* with signature.
• Publish — expose ts-based external metrics with TraceID and contracts.* outcomes.

VI. Contracts & Assertions (Examples)

• C60-01: abs(offset_p99) ≤ tol_offset.
• C60-02: abs(skew_p95) ≤ tol_skew (units "ppb").
• C60-03: MTIE(tau) ≤ bound_mtie(tau) for tau ∈ TauSet.
• C60-04: loss_rate ≤ tol_loss, reordering ≤ tol_reorder.
• C60-05: delta_form ≤ tol_Tarr; check_dim(expr)=true.
• C60-06: alpha_spend_sync ≤ budget_alpha (for sequential tests/alerts).

VII. Implementation Bindings I60- (Prototype)*

• ingest_sync_frames(stream) -> frames
• sanitize_and_align(frames, policy) -> frames' (alignment to tau_mono and anomaly handling)
• estimate_offset_skew(frames', method) -> {offset, skew, U}
• estimate_asymmetry(frames', scheme) -> asym, U_asym
• compute_stability(offset_series, TauSet) -> {TIE, MTIE, tdev}
• servo_update(offset, cfg) -> loop_state'
• assert_sync_contract(metrics, rules) -> report
• emit_sync_manifest(metrics, contracts, meta) -> manifest.sync
• Invariants: unique(gm_id, domain); Delta_t > 0; sum(loss_window) ≤ tol_loss; delta_form ≤ tol_Tarr.

VIII. Cross-References

• Time-base modeling, Allan family & noise decomposition: EFT.WP.Metrology.TimeBase v1.0 Chapters 2 / 7.
• Cleaning contracts & manifests: EFT.WP.Methods.Cleaning v1.0 Chapter 10 and Appendix C.
• Statistical uncertainty & SLOs: EFT.WP.Methods.CrossStats v1.0 Chapter 14 and Appendix E.

IX. Quality Gauges & Risk Control

• SLIs: offset_ns.{p50,p95,p99}, mtie(tau), tdev(tau), latency_ms_p99, loss_rate, gm_switch_count.
• SLOs: publish MTIE bounds on TauSet; offset_ns_p99 ≤ target.
• Risks: asymmetry drift, virtualization noise, GNSS spoof/unlock, routing changes, temperature & aging.
• Rollbacks: GM re-election, BCM degrade modes, bandwidth reductions, and alert suppression policies.

Summary