A memory system that is an example of the present disclosure comprises a memory fabric and an overlay. The memory fabric comprises: a network of memory components interconnected by optical interconnects, and memory address spaces of the memory components are aggregated and exposed as if the network were a single memory resource. The memory fabric further comprises router modules to implement steps of a fabric routing protocol to route memory-addressing requests along paths to destination memory components in the memory fabric. The overlay increases resiliency of the memory system and comprises overlay nodes to receive and forward memory-addressing requests from client programs and to implement steps of an overlay routing protocol to selectively control routing of received memory-addressing requests, to destination memory components, either along paths determined according to the fabric routing protocol or along alternative paths via overlay nodes.