Expand Configuration and Management Manual (H06.21+, J06.10+)

Subsystem Description
Expand Configuration and Management Manual — 529522-013
17 - 4
Expand Line-Handler Processes
Expand-Over-NAM Line-Handler Processes
Expand-over-NAM line-handler processes use the NETNAM protocol to access the
network access method (NAM) interface provided by an X25AM or a SNAX/APN
line-handler process.
Expand-Over-NAM With X25AM
The X25AM subsystem provides access to X.25 packet-switched data networks
(PSDNs). The X25AM subsystem consists of a layered set of protocols that
corresponds to the lower three layers of the International Standards Organization (ISO)
Open Systems Interconnection (OSI) Reference Model.
Each X25AM line-handler process controls a single data communications line and
supports both permanent virtual circuits (PVCs) and switched virtual circuits (SVCs).
Up to 254 circuits can be configured for each X25AM line-handler process. One
X25AM line-handler process can service multiple Expand-over-NAM line-handler
processes.
When it interfaces to an X25AM line-handler process, the Expand-over-X.25 line-
handler process sends data over one virtual circuit running in the X25AM line-handler
process; the X25AM line-handler process manages the physical communications line.
The Expand-over-X.25 line-handler process is also responsible for
•
Establishing the connection between itself and the X25AM line-handler process
•
Reestablishing communications with the remote server when an unavailable
network service becomes available again
•
Error recovery
Expand-Over-NAM With SNAX/APN
The SNAX/APN subsystem provides access to IBM Systems Network Architecture
(SNA) networks. The SNA network can be a traditional network of host mainframes
and front end processors, an advanced peer-to-peer network of IBM AS400 systems,
or a mix of these two types of networks. SNAX access methods support a wide range
of physical connections to IBM systems and networks, including
•
Synchronous Data Link Control (SDLC) connections, using RS-232, RS-449, X.21,
and V.35 electrical interfaces
•
X.25 packet-switched networks
•
Token Ring networks
•
Host channel connections
The SNAX/APN subsystem consists of a service-manager process and one or more
SNAX/APN line-handler processes. Each Expand-over-SNA line-handler process is
Note. For more information on the Expand-to-NAM interface, see Expand-to-NAM Interface on
page 17-49.