Error detection in an interconnection network for an integrated circuit

An interconnection network is provided for managing data transfer between a plurality of nodes of an integrated circuit. The interconnection network has at least one transmission path originating from an upstream location of the interconnection network, each transmission path being arranged to transmit data blocks from the upstream location to an associated downstream location within that transmission path. Digest generation circuitry is used to generate digests for data blocks, and fault detection circuitry provided in association with the upstream location is arranged to determine presence of a fault condition in the interconnection network. The digest generation circuitry is arranged to generate an upstream digest for a given data block at the upstream location, and to generate a corresponding downstream digest for the given data block at the associated downstream location. The fault detection circuitry is arranged to receive upstream digests from the upstream location and corresponding downstream digests received via a return path from each downstream location, and to determine presence of the fault condition based on a comparison of each upstream digest with its corresponding downstream digest.