Expand Management Programming Manual

SECTION 1
INTRODUCTION
The EXPAND network-operating software is a communications subsys-
tem that links together as many as 255 geographically distributed
Tandem NonStop computer systems to create a network having the
same reliability, capacity to preserve database integrity, and
potential for modular expansion as a single system.
OBJECTS CONTROLLED BY THE EXPAND SUBSYSTEM
An EXPAND network consists of two or more Tandem NonStop systems
connected by data-communications paths. Each system in a network
is called a node. A process called the Network Control Process
(NCP) runs in each node of a network. Each node might also
contain a process called the EXPAND manager process. (The
architecture of the EXPAND subsystem is described in more detail
later in this section.)
An EXPAND path is a logical connection between two nodes in a
network. For each path between adjacent nodes in a network,
there is an EXPAND line-handler process that controls the path.
An EXPAND path between adjacent nodes can consist of several
lines. An EXPAND line is a communication link such as a full-
duplex telephone line, an X.25 virtual circuit, a fiber-optic
cable, or a satellite link.
The EXPAND subsystem controls EXPAND paths and lines. Target
objects for some commands can also be parts of the EXPAND
subsystem itself: line-handler processes, the EXPAND manager
process, and the NCP.
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