One Ethernet switch module or copper pass-thru module is required in switch module bay 1 of your BladeCenter S chassis to enable communication between the blade servers and an external Ethernet network.
You have the option of installing an addition Ethernet switch module in I/O module bay 2. Remember that if you do, you will also need to install an Ethernet expansion card option in each blade server that will access the external Ethernet network through the switch module in I/O module bay 2.
For more information about Ethernet switch modules, see the Ethernet switch module documentation. To determine which Ethernet switch modules are compatible with the BladeCenter S chassis, see the IBM ServerProven Web site.