In the SNA architecture, a Network Addressable Unit (NAU), sometimes called a Network Accessible Unit, forms the origin or destination of the data packets, which in SNA networks are called Path Information Units
(PIU). The NAU can act as a host-based Logical Unit
(SSCP) for thePath Control
Layer's working units. In the SNA architecture, Path Information Units are sent to the Network Addressable Unit, which then routes them through the SNA network. This distinguishes the SNA architecture network protocol from other network protocols where messages are routed through the network based on addresses.