Lenovo 8721 Product Manual page 9

I/O architecture
Each half-wide compute node (such as the ThinkSystem SN550) has two adapter slots, and each full-wide
compute node (such as the ThinkSystem SN850) has four adapter slots. The adapter slots in each
compute node route through the chassis midplane to the switch bays. The architecture supports up to
eight ports per adapter.
The following figure shows how two-port adapters are connected to switches installed in the chassis.
Figure 5. Logical layout of the interconnects between two-port I/O adapters and I/O modules
A four-port adapter doubles the connections between each adapter and switch pair (for example, a four-
port adapter in A1 in each compute node routes two connections to switch 1 and two connections to
switch 2).
The following figure shows how four-port adapters are connected to switches that are installed in the
chassis.
Flex System Enterprise Chassis 9