Installing the S25P System 27Connecting Three SwitchesForce10 recommends the ring topology, as outlined above (Figure 14 on page 25), for stacking S-Seriesswitches, providing redundant connectivity. Using the example of three switches in the stack (Figure 16):1 Starting with the switch at the bottom of the stack, insert one end of the first cable into Stack Port A.2 Insert the other end of the first cable into Stack Port A of the middle switch.3 Insert the second cable into Stack Port B of the middle and top switches.4 Connect the remaining cable to the top and bottom switches by inserting one end of the cable into theopen Stack Port B of the bottom switch and the other end of the cable into Stack Port A of the topswitch.Figure 17 S25P Rear View Showing Ring Topology StackingSupplying PowerSupply power to the units in a stack only after they are mounted and the stack ports are connected. There isno on/off switch, and the stack members partly determine the stack management unit from the order inwhich they come online (see below).The S25P switch has two AC receptacles in the rear of the chassis (see Figure 2 on page 9). The system canuse either power source independently, or act in load-sharing mode. Failover is hitless.Danger: To prevent electrical shock, make sure the switch is grounded properly. If you do not groundyour equipment correctly, excessive emissions can result. Use a qualified electrician to ensure that thepower cables meet your local electrical requirements. See other relevant cautions in Information Symbolsand Warnings on page 5.STACKSTACKSTACKSTACKSTACKSTACKfn00152s50V1Stack Port A Stack Port B