Under normal running conditions, one Fabric Interconnect (primary) serves as an active member and the other Fabric Interconnect serves as a standby. A split brain occurs when there is L1, L2 network failure between the primary and secondary Fabric Interconnects. Cisco developed the chassis midplane in such a way that there is EEPROM divided into sections, one for each Fabric Interconnect.

Fabric Interconnect A has the read/write access to one section of EEPROM through the chassis management controller and the read-only access to the other EEPROM.