RadiSys ATCA-4616 Specifiche Scaricare il pdf (Pagina 106)

Troubleshooting

106

OnlytheswitchingportionoftheSCMsactinActive‐Activemode.TheShMCsareneverin

dualactivestateunlessthere'sac atas trophicbusfaultthatdoesnotallowany

communicationbetweentheSCMs.TheShMCsarbitratetobecomeactiveorstandbyassoon

astheyinitialize.Ifthey

everbecomedual‐active,theyareconstantlyprobingeachother's

statesandwouldquicklynoticethestatemismatchanddore‐arbitration.

TheIPMBbusesAandBareredundantandnosynchronizationoccursbetweenthetwo

buses.TheShMCsthatareconnectedtomultipleIPMBsfollowaround‐robinarbitration

protocol.Requestsaretransmittedinround‐robinmanneronthetwoIPMBs.

IfanShMCfailstoreceivearesponsemessagefromanyslot(forexampleslot#3),it

retransmitstherequestmessageuptothreetimesat250msecintervals.The250msec

intervalissuggestedbyPICMGtoallowformanagedFRUcommunication,thusitcantakeup

to750msecstotimeout.

IfaclientcannotaccessIPMCrightaway(duetoBUSbusy),theIPMCkeepstryingtoarbitrate

onthebusuntilitgetsaccessandcantransmitthebytes.Otherfunctionsarenotpendingin

thisstate.Amessagingqueueismaintainedandmessagesthatneedtogettransmittedare

putinthisqueue.Thelow‐levelI

Cdriverpicksthemupfromthisqueuefortransmission.All

otherIPMCfunctionscarryonwhilethisishappening.Thetasksofhot‐swap,sensor,FRU

data,etc.areallhandledinaseparatethread.

IPMB bus redundancy

Thesamemessageisnottransmittedsimultaneouslyonthesamebus.Messagesare

transmittedinaround‐robinmanner.Soifmessage1istransmittedonbusA,message2will

beonbusB,message3willbeonbusAandsoon.TheIPMCkeepstrackofwhatbuswas

usedforthelasttransactionandusestheotherbusforthenext.Ifabusisisolatedoranerror

isdetected(reportedbytheIPMB‐0sensor)thenalltransactionshappenontheother

availablebus.

IPMBIsolationcausesarenotedinthePICMGspecitselfwhereitdefinestheIPMB‐0sensor

eventstates.Themostcommoncausesareasfollow:

1h=UnabletodriveclockHI

2h=UnabletodrivedataHI

3h=UnabletodriveclockLO

4h=UnabletodrivedataLO

5h=Clocklowtimeout

6h=Undertest(theIPMControllerisattemptingtodetermineifitiscausingabushang)

7h=UndiagnosedCommunicationsFailure

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RadiSys ATCA-4616 Specifiche Pagina 106