Expand Configuration and Management Manual (G06.24+)

Subsystem Description
Expand Configuration and Management Manual—523347-008
18-2
Expand Subsystem Components
Expand Subsystem Components
The Expand subsystem comprises the following major components:
•
Expand Line-Handler Processes on page 18-2
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Network Control Process ($NCP) on page 18-7
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Expand Manager Process ($ZEXP) on page 18-7
Expand Line-Handler Processes
An Expand line-handler process is responsible for
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Maintaining the communications path between two adjacent nodes. A path is a
logical connection that can consist of one or more parallel lines. A line is a single
physical communications link between two nodes.
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Implementing the HP proprietary End-to-End protocol. The End-to-End protocol
is explained in Path Function of the Expand Subsystem on page 18-13.
•
Establishing a connection with an X.25 Access Method (X25AM) line-handler
process, a SNAX/Advanced Peer Networking (SNAX/APN) line-handler process, a
NonStop TCP/IP process, the ServerNet monitor process ($ZZSCL), or the FOX
monitor process ($ZZFOX), if these communications methods are used.
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Forwarding packets addressed to other nodes.
Each system in an Expand network can contain as many as 255 Expand line-handler
processes.
Expand Path Types
You can configure an Expand path as
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A single-line path, which is a path that consists of one line.
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A multi-line path, which is a path that consists of more than one line. You can
configure a multi-line path to consist of up to eight parallel lines.
•
A member of a multi-CPU path, which is a path that consists of more than one
path. You can configure a multi-CPU path to consist of up to 16 parallel paths,
including multi-line paths.
An Expand line-handler process that manages a single line performs both path and line
functions with a single logical device.
A multi-line path requires a logical device to manage the path function (called a path
logical device) and a separate logical device for each line in the path (called a line
logical device). Each line logical device is associated with the path logical device that
manages the path to which the line belongs. The path logical device and the line
logical devices with which it is associated are regarded as a single Expand line-handler
process and must be configured in the same processor pair.