Pilz PSSnet SHL 8T MRP User Manual
Page 344
Glossary
344
PSSnet SHL - Command Line Interface
Pilz GmbH & Co. KG, Felix-Wankel-Straße 2, 73760 Ostfildern, Germany
UPMB. The second of two UPMs in
Motorola's MPC855T processor.
USP. An abbreviation that
represents Unit, Slot, Port.
V
Virtual Local Area Network.
Operating at the Data Link Layer
(Layer 2 of the OSI model), the
VLAN is a means of parsing a single
network into logical user groups or
organizations, as if they physically
resided on a dedicated LAN
segment of their own. In reality, this
virtually defined community may
have individual members peppered
across a large, extended LAN. The
VLAN identifier is part of the 802.1Q
tag, which is added to an Ethernet
frame by an 802.1Q-compliant
switch or router. Devices
recognizing 802.1Q-tagged frames
maintain appropriate tables to track
VLANs. The first three bits of the
802.1Q tag are used by 802.1P to
establish priority for the packet.
VLAN. See “Virtual Local Area
Network” on page 344.
vMAN. Virtual Metropolitan Area
Network.
W
WAN. See “Wide Area Network” on
page 344.
Web. Also known as World-Wide
Web (WWW) or W3. An Internet
client-server system to distribute
information, based upon the
hypertext transfer protocol (HTTP).
Wide Area Network. A WAN is a
computer network that spans a
relatively large geographical area.
Typically, a WAN consists of two or
more local-area networks (LANs).
X
X.500. A directory standard that
enables applications like e-mail to
access information that can either
be central or distributed. The benefit
of a directory is the ability to
minimize the impact on the user of
changes to a network. The standard
is broken down under subsequent
standards, as follows:
X.501 Models
X.509 Authentication framework
X.511 Abstract service definition
X.518 Procedures for distributed
operation
X.519 Protocol specifications
X.520 Selected attribute types
X.521 Selected object types
XModem. One of the most popular
file transfer protocols (FTPs).
Xmodem is fairly effective at
detecting errors. It sends blocks of
data together with a checksum and
then waits for acknowledgment of
the block's receipt. The waiting