In IBM's Systems Network Architecture ( SNA ), a logical unit (LU) identifies an end user in an SNA network . By end user, IBM means either a human being that is interacting with the network or an application program that is indirectly representing such an end user. Two logical units that communicate depend on physical connections being established through associated physical units ( PU s). The network point at each end of a communication that sets up the communication session between logical units is called the system services control point (SSCP) . Typically, a logical unit is a unique connection to an application program. A physical unit is usually a hardware device, such as a terminal control unit. IBM's Virtual Telecommunication Access Method ( VTAM ) is used by an application program to manage session and communication requests on behalf of logical units.
In SNA, LU 6.2 is a type of logical unit used to represent end users in a distributed processing environment.