interface message processor (Arpanet) (IMP)

Interface Message Processor (IMP) is a switching node. The term Interface Message Processor was formerly used for the nodes in the data packet switching in ARPANET. Later, the IMPs were then called data packet switching nodes, Packet Switching Node( PSN).

The term Interface Message Processor is rarely used today. The generally applicable, network-independent designation for such a switching component is node.