Slot 6 is capable of housing an SFM or a supervisor incorporating an SFM, such as the Supervisor-720. This slot may also support any line card or module, with the exception of supervisors that would normally be placed in slot 1 or 2. This slot is used for the redundant fabric module or supervisor module if a failover pair is installed. Though a single fabric module or supervisor can be installed in this slot, slot 5 is generally used for single-supervisor/SFM installations. Slot 7 Slot 7 is capable of housing any line card or module, with the exception of supervisors or SFMs. Slot 8 Slot 8 is capable of housing any line card or module, with the exception of supervisors or SFMs. Slot 9 Slot 9 is capable of housing any line card or module, with the exception of supervisors or SFMs. The 6506-chassis slots are allocated the same way, with the obvious difference that there are no slots 7, 8, and 9; the 6513-chassis slots are allocated the same way, but with the addition of slots 10-13, which can house any line card or service module apart from supervisors or SFMs. These last four slots in the 6513 chassis cannot sup- port certain fabric-only blades. Consult the Cisco documentation for specifics when ordering cards for this chassis. Enhanced Chassis A series of enhanced 6500 chassis, identified by an e at the end of the chassis part number, are also available. An example of an enhanced chassis is the 6500e. The enhanced chassis are designed to allow more power to be drawn to the line cards. The advent of Power over Ethernet (PoE) line cards for Voice-over-IP applications was one of the key drivers for this evolution. The enhanced chassis use high-speed fans to cool these power-hungry modules. The e-series chassis also provide a redesigned backplane that allows for a total of 80 Gbps of throughput per slot. This represents a theoretical doubling of the capacity of the standard 6500 chassis (40 Gbps of throughput per slot), though at the time of this writing, there are no line cards or supervisors that support this speed