TSN Time-Aware Shaper Workbench
Step through time-aware gates, guard bands, cycle timing, and deterministic Ethernet queue scheduling
animation
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Interactive TSN time-aware shaper animation for learning IEEE 802.1Qbv scheduled traffic, gate control lists, cycle time, base time, guard bands, traffic classes, clock synchronization, and admission risk.
Interactive animation
TSN
Time-aware shaper
TSN Time-Aware Shaper Workbench
Watch an egress port use a gate control list to open and close traffic-class queues on a repeated cycle. The goal is not priority alone: it is transmission at planned times using synchronized clocks, guard bands, and admitted traffic budgets.
Clock syncCurrent phase
All gates closedGate state
Low riskSchedule risk
Goal
Separate time sync, gate schedule, guard band, and admission control in deterministic Ethernet.
Try
Compare motion control, vision burst, tight cycles, missing guard band, and clock drift.
Watch
Use Step to connect each gate opening to the gate control list and queue state.
Check
Decide whether a deterministic failure is caused by overload, sync error, or an unsafe guard band.
Gate Control List and Queue Flow
A motion-control bridge uses synchronized time to repeat a gate control list. A short guard band protects the control slot, then control, video, and best-effort queues use their assigned transmission windows.
Ready: motion control loaded
Grandmaster802.1AS time
Bridge EgressGCL and queues
Controllerscheduled frames
Plant ITbest effort frames
Guard band
closed
Control queue
closed
Video queue
closed
Best effort
closed
Gate Control List
Schedule Trace
Start: a time-aware shaper only works when participating devices share a sufficiently accurate time base.
Timing Budget
1000 usCycle time
300 usControl window
380 usBest-effort remainder
boundedControl latency
Diagnosis
Step through the schedule to see which gate is open, what can transmit, and why a bounded-latency claim depends on the full schedule and time synchronization.
Open gatenone yet
Timing clueBase time and cycle time align the repeated schedule.
RiskA gate schedule is only deterministic if all relevant hops are synchronized and admitted traffic fits.
Quick Reference
- Time-aware shaper: opens and closes traffic-class gates according to a repeating schedule.
- Gate control list: ordered entries define gate states and time intervals for an egress port.
- Guard band: prevents a lower-priority frame from starting so late that it overlaps a scheduled slot.
- Clock sync: bridges and end stations need aligned time, commonly from IEEE 802.1AS timing.
How To Debug
- If control latency spikes, check whether every hop has compatible base time, cycle time, and gate list entries.
- If best-effort frames disrupt control traffic, inspect guard band, frame preemption support, and maximum interfering frame size.
- If a schedule looks correct but misses, check time sync error, grandmaster changes, and whether end stations are time-aware.
- If new traffic is added, recompute admission and per-hop egress windows before claiming deterministic behavior.
Concept Map
Base TimeSchedule start time shared by synchronized devices.
Cycle TimePeriod after which the gate list repeats.
Gate StateOpen or closed state for each traffic class queue.
Traffic ClassQueue selected from priority and stream classification.
AdmissionChecks whether new streams fit the reserved timing budget.
PreemptionOptional support can reduce guard-band waste when configured.
Technical Accuracy Notes
- Scheduled traffic is based on egress queue gates. It does not by itself guarantee end-to-end determinism unless every relevant hop and stream budget is considered.
- Priority is not enough. A high-priority best-effort frame can still interfere if gate timing and guard bands are not configured correctly.
- Clock synchronization error consumes timing margin. A schedule should include tolerances for clock drift, residence time, and link delay assumptions.
- Guard bands protect scheduled windows; frame preemption can reduce the required guard-band cost where supported.
- The numbers here are teaching values, not a certified network calculus or vendor configuration tool.