LAN Configuration and Management Manual

LAN Configuration and Management Manual—520469-012
2-1
2
Introduction to the SLSA Subsystem
This section describes the ServerNet LAN Systems Access (SLSA) subsystem
architecture.
Overview of SLSA
In the NonStop system, the communications adapter communicates with multiple
processors simultaneously delivering data directly to the processor that contains the
target client.
SLSA operates within the queued input/output (QIO) segment environment of the
NonStop system and uses the QIO subsystem to communicate with SLSA clients. Data
that meets a filtering criteria is delivered to the QIO queue in the specified processor.
SLSA provides that filtering.
SLSA is the interface between NonStop processors and adapters. SLSA gives
processors access to the LAN by providing the required input/output (I/0) processes
between the LAN service providers and a LAN.
SLSA LAN clients are processes that use the LAN subsystem to send and receive data
on a LAN attached to the NonStop server. Three client interfaces are available:
NonStop TCP/IP, PAM, and NonStop IPX/SPX.
SLSA software components reside in the host node and the adapters. Table 2-1
describes these components and Table 2-2
describes the SLSA data structures in the
adapters. Figure 2-1
on page 2-4 shows the relationship between the SLSA
components, processors, and adapters.
Overview of SLSA
2-1
ServerNet Architecture and SLSA 2-5
The SLSA Role Within the System 2-7
Architecture of the SLSA Subsystem 2-10
Fault Tolerance of the SLSA Subsystem 2-16
Note. SLSA supports many different adapters installed in different system types. See Adapters
on page 2-12 or Adapter Manuals
on page 1-7.