When connecting multiple DRds with S-ACPs together using SmartLink (e.g. Belden 8471 or approved alternate), you need to adjust the termination jumpers in the secondary racks. The DRd that houses the S-SPM should use the default HALF Lon Termination, and its S-ACP should be configured as station master. The other DRds should not be configured as station masters, and their Lon Termination should be set to Off.
There is a topology issue to consider with SmartLink interconnected S-ACPs that can result in erratic system response to SmartLink commands. This issue only affects systems with two or more S-ACPs on the SmartLink bus. A single S-ACP connected via SmartLink to SmartPack, SmartSwitch, or CEM+ with SmartLink Power Supply functions normally.