These are self-study crib notes and may not be 100% accurate.
What happens when a client roams to a different location in an SDA fabric?
The ETR at the new location sends a map-register notification to the control plane node.
The control plane node flushes it’s mapping database and updates it with the new mapping.
At this stage, other edge nodes (cache) still think the client is at its original location.
The control plane node sends a notification to the original ETR where the client was originally connected to inform it that the client has moved.
When data is received on the original ETR from an edge node destined for the client, the original edge node replies with a notification telling that edge node to go and get an updated mapping from the control plane node but it will deliver the packet to the new destination in the meantime.