Filter
Top Products
36 Chapter 1
SNA Terms and Concepts
Basic SNA Concepts
In a subarea network, the CP on an SNA node acts as a
type 2.0 PU. It communicates with an SSCP on a host
and does not communicate with other CPs in the
subarea network.
When participating in an APPN network, the CP
exchanges network control information with the CPs in
adjacent nodes. The CP can also function as an
independent LU of type 6.2. The CP acts as the default
LU for TPs on the local node. For more information
about the APPN control point, see “APPN Control
Point”.
Sessions
NAUs communicate with NAUs in other nodes over temporary logical
communication channels called sessions. Before two TPs can
communicate, their LUs must establish a session. The LU that manages
the session on the local node is the local LU; the LU that manages the
session on the remote node is the partner LU.
Session Types
SNAplus2 is primarily concerned with the following types of sessions:
LU-LU sessions
In order for two TPs to communicate, the LUs that
support the TPs must first establish an LU-LU session.
In general, a session is established when a TP in one
SNA node tries to communicate with a TP in another
node and no existing session between the LUs on the
two nodes is available.
SSCP-LU sessions
A dependent LU (see “Dependent and Independent
LUs”) must have an active SSCP-LU session with an
SSCP on a type 5 node before it can have a session with
an LU in the subarea network. Once an SSCP-LU
session is active, a dependent LU can solicit an LU-LU
session.
SSCP-PU sessions