The hot-swappable Input/Output (I/O) cards provide excellent in-service expansion capabilities in convenient sets of 16 ports per I/O card for the HDX576, thus allowing re-configuration without interrupting signal processing. This I/O card is supplied WITHOUT SFP modules. Each individual I/O Card lists available ports as 1 through 16. The Fan Tray module lists the port numbers (all numbering is bottom to top, left to right. A LED located at the top of each I/O card indicates when power is ON to that card.