21-EFT.WP.Metrology.Sync v1.0 | Chapter 5 — Protocol Families & Implementations (PTP / NTP / SyncE / White Rabbit)

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Chapter 5 — Protocol Families & Implementations (PTP / NTP / SyncE / White Rabbit)

One-line objective: Establish a unified metrology and implementation baseline for PTP/NTP/SyncE/White Rabbit — spanning message and frequency transfer, asymmetry and compensation, servo convergence, and compliance templates — so that offset/skew/J and T_arr remain auditable and aligned under mixed-protocol operation.

I. Scope & Objects

1. Applicable stacks
   • PTP (IEEE 1588; Default/Telecom/Power profiles), NTP (v4/v5 modes), SyncE (G.826x/G.827x), White Rabbit (WR, i.e., PTP + SyncE + phase measurement).
   • Single-/multi-domain deployments, Ethernet/TSN physical links, datacenter and carrier edges, satellite/fiber hybrid backhaul.
2. Inputs
   • Capabilities: hwts ∈ {none, mac, nic, phy}, synce_cap, wr_cap, profile_id.
   • Links & devices: R_bps, L_bits, lambda_tx/rx, fiber_len, temp, esmc.QL.
   • Messages & measurements: PTP T1..T4, correctionField, t_res; NTP t1..t4; WR phase-difference samples and calibration constants.
3. Outputs
   • Unified gauges: offset, delay_rt, freq_error_ppb, wander(MTIE,tdev), holdover_drift.
   • Compliance artifacts: manifest.sync.proto.* (protocol, configuration, measurements, thresholds, and signature).

II. Terms & Variables

1. PTP/NTP
   • T1..T4, CF12/CF34, t_res, asym, delay_rt, profile_id, BMCA state.
   • NTP endpoint timestamps t1..t4, sampling window W, jitter estimate j_ntp, filter depth N.
2. SyncE / WR
   • f_in, f_out, e_ppm (frequency error), esmc.QL (quality level), PRTC/PRC.
   • WR link: Delta_tx/rx (port fixed delays), delta_ms, delta_sm (fiber delay master↔slave), alpha (wavelength asymmetry factor).
3. Servos
   offset, skew, drift, Kp/Ki, tau_loop, state ∈ {free, acquire, track, holdover}.
4. Time & arrival
   tau_mono, ts, T_arr, gamma(ell), n_eff, c_ref, delta_form.

III. Axioms P605-*

• P605-1 (Layered objectives): SyncE provides syntonization (frequency alignment); PTP/NTP/WR provide synchronization (time/phase). Always close frequency before phase.
• P605-2 (Profile immutability): Each port uses a fixed profile_id and parameter set (announce/interval/logSync/peerDelay); no mixed-profile operation.
• P605-3 (Hardware-first): Prefer hardware timestamping for PTP/WR; enable NTP only when HW is unavailable or across public networks, and publish larger U.
• P605-4 (Explicit asymmetry): Model link asymmetry via asym or WR alpha explicitly; do not bury it inside offset.
• P605-5 (Dual-form mandatory): Any propagation/arrival measurement must compute both T_arr forms and record delta_form.
• P605-6 (Dimensional integrity & manifests): Validate units/dimensions for any time/frequency/phase operand and persist to manifest.sync.proto.*.

IV. Minimal Equations S605-*

• S605-1 (PTP offset/delay with correctionField and asymmetry)
  T2' = T2 - CF12；T4' = T4 - CF34
  delay_rt = ( ( T2' - T1 ) + ( T4' - T3 ) ) / 2
  offset = ( ( T2' - T1 ) + ( T3 - T4' ) ) / 2 - asym
• S605-2 (NTP offset/delay with filtering)
  theta = ( ( t2 - t1 ) + ( t3 - t4 ) ) / 2
  delta = ( t4 - t1 ) - ( t3 - t2 )
  Filtering: theta_hat = argmin_theta{ delta } using the minimum-RTT sample within W; jitter j_ntp = RMS( theta - theta_hat )。
• S605-3 (SyncE frequency transfer)
  f_out = f_in * ( 1 + e_ppm * 1e-6 )
  Drift bound: |e_ppm| ≤ e_max; steady-state wander is evaluated in windows via MTIE(τ), tdev(τ)。
• S605-4 (WR asymmetry compensation & phase measurement)
  asym_wr = 0.5 * ( delta_ms - delta_sm ) + ( Delta_tx_master - Delta_rx_slave + Delta_tx_slave - Delta_rx_master ) / 2
  offset_wr = offset_ptp - asym_wr
  where delta_ms, delta_sm come from DDMTD/phase-alignment; alpha enters delta estimation as the wavelength-dependent correction。
• S605-5 (Dual-form arrival delta)
  delta_form = | ( 1 / c_ref ) * ( ∫ n_eff d ell ) - ( ∫ ( n_eff / c_ref ) d ell ) |
• S605-6 (Servo linearization—approximate)
  First order: skew_{k+1} = skew_k - Kp * offset_k；second order: offset_{k+1} = offset_k + Ki * skew_k * Δt
  Convergence (linear region): 0 < Kp < Kp_max, 0 < Ki < Ki_max, and phase-margin constraints satisfied。

V. Implementation Flow M60-5 (Protocol Families & Implementations)

• Capability probe & protocol choice
  Discover hwts/synce_cap/wr_cap, network hierarchy and upstream quality; select the primary stack {WR|PTP}; enable SyncE alongside; keep NTP as the public-network fallback.
• Profile tailoring & parameter freeze
  Select profile_id; set logSyncInterval, announceInterval, delayMechanism ∈ {E2E,P2P}, and PTP domain; configure SyncE line encoding and esmc.QL thresholds.
• Link calibration & asymmetry modeling
  Compute/measure asym: PTP via loopback/two-way; WR via delta_ms/delta_sm, Delta_tx/rx, and alpha; record uncertainties.
• Servo tuning & state machine
  Converge frequency loop (SyncE/NIC PLL) before phase loop (PTP/WR); configure Kp/Ki/tau_loop with lock/holdover/fallback thresholds.
• Operations monitoring & exception handling
  Collect offset/delay_rt/freq_error_ppb/MTIE/tdev; on QL downgrade, BMCA mismatch, or packet loss/jitter anomalies, trigger switching and rate limiting.
• Manifest & signing
  Emit manifest.sync.proto.*: protocol/parameters/calibration/thresholds/evaluations/signature; persist for replay.

VI. Contracts & Assertions C60-5*

• C60-51 (Profile consistency): profile_id agrees with port role; delayMechanism matches at both ends.
• C60-52 (Bias gates): offset_p99 ≤ offset_budget; delay_rt_p99 ≤ delay_budget.
• C60-53 (Frequency alignment): |freq_error_ppb|_p95 ≤ freq_budget_ppb; MTIE(τ) ≤ MTIE_max(τ).
• C60-54 (NTP fallback): delta_p95 ≤ delta_ntp_max; j_ntp ≤ jitter_ntp_max.
• C60-55 (SyncE quality): esmc.QL ∈ {PRC, PRTC, G.8275.* compliant}; on downgrade, de-weight or re-parent.
• C60-56 (WR asymmetry): |asym_wr| ≤ asym_wr_max; cal_age ≤ cal_ttl.
• C60-57 (Dual-form delta): delta_form ≤ tol_Tarr.
• C60-58 (Dimensional checks): check_dim(all expr) = true; external units match internal computation.

VII. Implementation Bindings I60- (Protocol Layer APIs)*

• ptp_config(port, profile_id, delay_mech, hwts) -> session
• ntp_config(servers, mode, filter_depth) -> session
• synce_enable(port, ql_policy) -> status
• wr_calibrate_link(port, method) -> {Delta_tx/rx, delta_ms, delta_sm, alpha, U}
• servo_tune(session, Kp, Ki, tau_loop) -> gains
• measure_sync_metrics(session) -> {offset, delay_rt, freq_error_ppb, MTIE, tdev}
• evaluate_sync_contracts(metrics, rules) -> report
• emit_proto_manifest(cfg, calib, metrics) -> manifest.sync.proto
• Invariants: state ∈ {free, acquire, track, holdover} with compliant transitions; sum(u^2)_components ≈ u^2(total); QL downgrade path recorded.

VIII. Cross-References

• Measurement links & timestamps: Chapter 4 of this volume.
• Time-base & noise metrics (Allan / MTIE / tdev): EFT.WP.Metrology.TimeBase v1.0 Chapters 7 & 14.
• Compliance & release freeze: Methods.Cleaning v1.0 Chapter 10 and Appendix C.
• Statistical uncertainty propagation: Methods.CrossStats v1.0 Appendix E.

IX. Quality SLIs & Risk Control

1. SLI/SLO set
   • offset_p50/p95/p99, delay_rt_p95/p99, freq_error_ppb_p95, MTIE@{τ_grid}, tdev@{τ_grid}。
   • ptp_announce_loss, ptp_sync_loss, ntp_delta_p95, esmc.QL_downgrade_rate, wr_asym_residual.
2. Risk & fallback
   • On offset_p99 breach: de-weight servo / switch GM or degrade to NTP.
   • QL downgrade: switch upstream or enter holdover and tighten tau_loop.
   • WR calibration expiry: force re-calibration or fall back to PTP+SyncE.
   • Sudden packet-jitter rise: increase filter_depth, rate-limit & flow-control, and trigger link-health checks.

Summary