The physical arrangement of network modules and switch fabrics (boards) in the ASX-4000 differs from that of the other switch models. The network modules are not physically embedded in the boards: they are inserted in separate slots and comunicate with the fabric over the switch backplane. Another difference lies in the physical arrangement of network modules: in the ASX-4000, each fabric supports two port cards, which in turn are logically divided into two interface groups, each containing up to four physical ports.
However, considering each interface group as a logical network module preserves the model used in the other switch types: each port card can be considered as a hardware unit consisting of one or two physical modules, which results in each fabric containing up to four network modules which in turn can contain up to four physical ports (as opposed to a maximum of eight ports in each module supported by the other switch types). The same applies to fault management: failure of a switch fabric results in its "contained" modules being out of operation.
The ASX-4000 is equipped with four AC or five DC power supply modules. Three AC or four DC PS modules are required to provide power to an ASX-4000. The fourth AC or fifth DC power supply is provided for redundancy.