The term data exchange is an older term for a central node
in integrated digital networks (IDN). A data exchange performs switching functions in circuit- or packet-switched networks. In general, they are electronic components in a meshed wide area network that are responsible for establishing connections, transporting and forwarding data streams. In ARPANET these devices are called Interface Message Processor (IMP), in transit system they are called Intermediate System (IS) or packet switching nodes.