. Single shelf network system 000 includes switching fabric 000, control card 000, I/O cards 000 and 000, and dedicated expansion card slot 000, which is not available for use with an I/O card. Single shelf network system 000 includes switching fabric 000, control card 000, I/O cards 000 and 000, and dedicated expansion card slot 000, which is not available for use with an I/O card. 