NOTE
NOTE
SNA Terms and Concepts
Basic SNA Concepts
On type 2.1 nodes (which can be APPN nodes), the control point provides PU services in addition to providing other services (see “Control Points”). Two type 2.1 nodes (such as SNAplus2 nodes) can communicate directly, without requiring the services of a host to establish communications.
Logical UnitsEach SNA node contains one or more logical units (LUs). An LU provides a set of functions that are used by TPs and end users to provide access to the network. LUs communicate directly with local TPs and devices.
SNA defines several types of LUs, each optimized for a specific class of applications. LUs of different types cannot communicate with each other, but LUs of the same type can communicate even though they reside on different kinds of systems.
For example, a TP running on a workstation that uses the
SNAplus2 supports the following LU types:
LU 6.2 (for APPC, 5250 and
LU 6.2 supports
6.2data stream is either an SNA general data stream (GDS), which is a
This LU type provides more functions and greater flexibility than any other LU type. Unless you are constrained by existing hardware or software, LU 6.2 is the logical choice when developing new applications.
Only LU 6.2 can provide independent LU functions.
LU 3 (for 3270 printing)
LU 3 supports application programs and printers using the SNA 3270 data stream.
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