异步流量整形器（802.1 Qcr）及其在汽车用例中的适用性.pdf

1、1Asynchronous Traffic Shaper(802.1Qcr)and its applicability to Automotive use-cases Alon RegevSeptember 20232 802.1Qcr ATS(Asynchronous Traffic Shaper)introduction Differences between talkers and switches Comparison between ATS vs.other TSN schedulers Interactions of ATS with other shapers Applicabi

2、lity to automotive applications Testing ATS for conformance and performance Summary and recommendationsAgenda3Defined in IEEE 802.1Qcr-2020Enables maximum latency guaranteesDoes not require time synchronizationProvides per-stream egress metering of trafficProvides fault isolationNodes and/or streams

3、 can be dynamically added,changed,or removed at runtimeEfficient use of Ethernet bandwidthAsynchronous Traffic Shaper-Introduction4For a single streamBased on the Token Bucket Algorithm with some tweaks to minimize hardware complexityApplied on each egress portPseudo-code on right is generalized mod

4、el*802.1Q defines this procedure in clause 8.6.11.3 for bridges and 49.1.2 for endstationsDetails:The scheduler algorithmdef ProcessFrame(frame):lengthRecoveryDuration=length(frame)/CommittedInformationRate emptyToFullDuration=CommittedBurstSize/CommittedInformationRate schedulerEligibilityTime=Buck

5、etEmptyTime+lengthRecoveryDuration bucketFullTime=BucketEmptyTime+emptyToFullDuration eligibilityTime=max(arrivalTime(frame),schedulerEligibilityTime)if not bridge or(eligibilityTime=(arrivalTime(frame)+MaxResidenceTimeInS):#The frame is valid if(eligibilityTime bucketFullTime)?BucketEmptyTime=sched

6、ulerEligibilityTime:BucketEmptyTime=schedulerEligibilityTime+eligibilityTime bucketFullTime Send(frame)at time(eligibilityTime)Else:#The frame is invalid Discard(frame)*Scheduler groups are not modeled in this single stream code for simplicity;see following slides for discussion of scheduler groupsP