Specifications

6
Troubleshooting
105
IPMI frame structure and message flow
TherearenoframesinIPMBmessages.Figure 10showsthemessageflowthroughanSCM
pairforIPMBmessages.
Figure 10. IPMI Message Flow
IPMB bus operation
TwoIPMBbuses(IPMB‐AandIPMB‐B)providetheprimarymeansofcommunication
betweenShMCs.TheactiveShMContheSCMisalsotheIPMCfortheSCMFRU,theCOM‐E,
andtheSCMRTM.TheactiveShMCperformsthesameoperationsotherIPMCsdoto
maintaintheirFRUs.Messagessenttoaddress0x82/0x84LUN0areallprocessedbytheIPMC
portionoftheShMCandarenotforwardedtotheShMS.Inaddition,theShMCperformsthe
tasksofarbitration(determiningactive/standbystate)andforwardingmessagesoverthe
serialinterfacetotheShMS.TheShMCisbasically
asupersetoftheIPMC.
Standby ShMSActive ShMS
Active ShMC
Standby ShMC
HSD
HSD
DEL
DEL
FRU
Table
FRU
Table
Fwd Event
Handler
Event
Handler
Event
Processors
Event
Processors
SEL
Local
SEL
Local
SEL
SEL
2
1
3
4
5
6
7
8
9