s. Specifically, if there is a nonfabric-enabled module in the chassis, the Supervisor-720 will not be able to run at 720 Gbps speeds. Here is an example of a 6509 that is filled with fabric-only 10/100/1000 Mb model 6748 Ethernet modules and two Sup-720 supervisors: 6509-1#sho mod Mod Ports Card Type Model Serial No. 48 CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX SAL05340V5X 48 CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX SAL09347ZXK CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX SAL05380V5Y 48 CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX SAL092644CJ 2 Supervisor Engine 720 (Active) WS-SUP720-3B SAL05304AZV 2 Supervisor Engine 720 (Hot) WS-SUP720-3B SAL09295RWB 48 CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX SAL05340Z9H 48 CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX SAL0938145M 48 CEF720 48 port 10/100/1000mb Ethernet WS-X6748-GE-TX SAL053415EC The command show fabric switching-mode demonstrates how each module is com- municating with the system. The output shows that all of the modules are using the crossbar switching bus and the Sup-720 is operating in dCEF mode, which allows for- warding at up to 720 Gbps: 6509-1#sho fabric switching-mode Fabric module is not required for system to operate Modules are allowed to operate in bus mode Truncated mode allowed, due to presence of aCEF720 module Module Slot Switching Mode Crossbar Crossbar Crossbar Crossbar Crossbar Crossbar Crossbar Crossbar Each fabric-only module has two 20 Gbps connections to the crossbar fabric bus, as we can see with the show fabric status or show fabric utilization command. Notice that the supervisors each have only one 20 Gbps connection to the fabric bus: 6509-1#sho fabric util channel speed Ingress % Egress % Chapter 17: Cisco 6500 Multilayer Switches For comparison, here is a 6509 operating with two Supervisor-720s, one fabric-only module, a couple of fabric-enabled modules, and one nonfabric-enabled module: 6509-2#sho mod Mod Ports Card Type Model Serial No. 48 CEF720 48 port 10/100/1000mb 