Backup firmware in a distributed system

In a distributed system of modules in a network, each module having an associated processor node comprising a processing unit for operating the associated module. The processing unit comprises a processor interface for communication in the network; and nonvolatile memory for storing code for the processing unit for operating the associated module, and for storing backup code for at least one other processing unit of another processor node in the network, the backup code for operating an associated module of the another processor node. In response to a request, the processing unit supplies the backup code to a processor node to be used to restore the code for operating the module associated with the requesting processor node.