erface modules are used, a Sup-720-equipped 6500 is capable of 400 Mpps. The SFM is what provides the actual switch fabric between all the fabric-enabled modules (recall that the SFM's functionality is included in the Supervisor-720, SO in this case, a separate module is not required). The module is actually a switch in and of itself that uses the backplane fabric bus as a communication channel be- tween the modules. For this reason, the speed of a 6500 can change with a new supervisor module. Fully interconnected Crossbar fabric fabric Input Output Input ports ports ports Output ports Figure 17-2. Switch fabric examples Figure 17-3 shows a visual representation of the backplane in a 6509 chassis. Looking at the chassis from the front, you would see each slot's connectors as shown. There are two backplane circuit boards separated by a vertical space. To the left of the space (at the back of the chassis) are the power connectors and the crossbar fabric bus. To the right of the space are the D, R, and C buses. A 6000 chassis would look the same to the right of the space, but have no crossbar fabric bus to the left. Architecture D Bus - EARL data bus Crossbar R Bus - EARL results bus switching C Bus - Control Bus or Ethernet Out Of Band Channel (EOBC) Power fabric Slot 1 - Supervisor (I, la, II, 32), Line card or Module Slot 2 - Redundant Supervisor (I, la, II, 32), Line card or Module Slot 3 - Line card or Module Slot 4 - Line card or Module Slot 5 - Supervisor (720), Switch Fabric Module, Line card or Module Slot 6 - Redundant Supervisor (720), Redundant Switch Fabric Module, Line card or Module Slot 7 - Line card or Module Slot 8 - Line card or Module Slot 9 - Line card or Module Figure 17-3. Cisco 6509 backplanes Certain slots are capable of taking specific modules, while other slots are not. The breakdown of slots in a 6509 is as follows: Slot 1 Slot 1 is capable of housing supervisor modules 1, 1A, and 2; line cards; or service modules. If there is only one Sup-1, Sup-1A, or Sup-2 in the chassis, it should res