1. What is the impact on the SPS appliances when we complete a SPP failover
SPS stores all the SPP cluster members and for password requests it connects to the first available node, starting with the primary. If that’s not available, it will try other nodes. SPS fetches information about the SPP cluster from the IP address that it was joined with originally (the primary at the time of the join). If an SPP is available at that IP address (does not need to be the primary), the SPS cluster will learn about changes in the configuration.
2. Is there anything SPS/Sessions-related that will break after the SPP failover (Pre-existing-Sessions ARPs, etc)?
As long as there is one SPP cluster member available and no changes are made in the SPP cluster configuration, everything will continue to function.
3. Does SPP communicate with SPS the failover process and update the configuration appropriately? Or is this a manual process? What are the steps for this process?
If the SPP cluster member can be replaced/reconnected on the same address, no manual action needs to be taken and the traffic will not be interrupted. If an SPP cluster member is permanently lost and cannot be replaced/reconnected, the cluster will need to be unjoined and rejoined using the new primary.