Patent ID: 6948024

Claim:
An expander device for isolating bus segments from one another in an I/O subsystem, the expander device coupling the bus segments for communication in the I/O subsystem, the expander device including: a first I/O interface circuit configured to be coupled to a first bus segment, the first I/O interface circuit being adapted to interface input and output communication signals with the first bus segment; a second I/O interface circuit configured to be coupled to a second bus segment and being adapted to interface the input and output communication signals with the second bus segment; and an expander controller coupled to communicate the input and output communication signals between the first and second I/O interface circuits, the expander controller being arranged to control communication between the bus segments, the expander controller including a segment controller adapted to generate a first signal, wherein the segment controller provides the first signal to the first and second I/O interface circuits to disable output of the communication signals from the first and second I/O interface circuits to the first and second bus segments, the disabling of the output of the communication signals isolates the first and second bus segments from one another in an isolation mode so that the communication signals received on either bus segment are allowed but are not transmitted, the expander transitions from the isolation mode to a normal operating mode in order to repeat communication signals by receiving the communication signals from one of the first bus segment or the second bus segment and outputting the communication signals to one of the second bus segment or the first segment.