Introduction to Networking for NonStop S-Series Servers

Glossary
Introduction to Networking for HP NonStop S-Series Servers—520670-005
Glossary-23
TSM
service has a high level of reliability, less work might be required of the Transport
Layer.
TSM. See Compaq TSM.
two-step read. A method of receiving incoming data by obtaining first the length of the
incoming message and then the data itself, in two separate calls.
uninterruptible power supply (UPS). A source of power, external to a device, capable of
supplying continuous power to the device in the event of a power failure.
User Agent (UA). Within a message handling system (MHS), a processing entity that acts
on behalf of a person or an application to send and receive messages.
user process. A process subject to creation, execution, and termination. Contrast with
system process.
virtual circuit. A logical connection between nodes in a packet-switching network. The
nodes communicate as if over a real physical circuit, although in actuality different
parts of a message can travel over different lines; the network provides addressing and
dynamic routing services.
virtual route. A logical connection between two subarea nodes in an IBM Systems Network
Architecture (SNA) network. A virtual route corresponds to a physical route, with
provision for transmission priorities, flow control (pacing of transmissions), and data
integrity (implemented with sequence numbers). Between its end points, a virtual route
can traverse other nodes, called intermediate nodes, which simply move the message
forward.
wide area network (WAN). A network in which the nodes are geographically remote from
one another and operates over a larger geographical area than a local area network
(LAN)—typically, an area with a radius greater than one kilometer. The elements of a
WAN may be separated by distance great enough to require telephone
communications. Contrast with local area network (LAN)
and ServerNet system area
network (ServerNet SAN).
window. A session between a workstation and an application, usually on a local area
network (LAN). With appropriate software, a workstation can support multiple windows,
each potentially for a different application; the interactions that make up each session
are displayed in a separate area of the screen. Each display area is also called a
window.
X.25. An interface recommendation developed by the International Telecommunications
Union–Telecommunications (ITU–T) for packet-switched data network (PSDN)
procedures. See also packet-switching and virtual circuit.
X and Y fabrics. X and Y fabrics are a collection of connected routers and ServerNet links
that, together, provide an interconnection for NonStop S-Series servers. Each
processor connects to both fabrics. The X fabric and the Y fabric are not connected to