ATM Adapter Installation and Support Guide

Glossary
ATM Adapter Installation and Support Guide—420013-002
Glossary-7
synchronous
synchronous. A mode of data communications transmission in which characters are
accumulated in a buffer at the sending terminal and then sent as a block of data.
Synchronous transmission normally uses external clocking provided by a synchronous
modem. The clocking scheme assumes that once transmission starts, characters will
arrive in a block at a predetermined speed. Contrast with asynchronous.
Synchronous Optical Network (SONET). An ANSI standard for transmitting information
over optical fiber. This standard is used or accepted in the United States or Canada
and is a variation of the SDH International standard.
system area network (SAN). A high-speed network, within a system, that connects
processors to each other and to peripheral controllers. A SAN has the performance of
a massively parallel interconnect, but has distribution capabilities similar to a local area
network (LAN). NonStop S-series servers support the ServerNet system area network
(ServerNet SAN).
TSM. See Compaq TSM package.
UNI. See User-Network Interface (UNI).
User-Network Interface (UNI). An interface point between ATM end users and a private
ATM switch, or between a private ATM switch and the public carrier ATM network;
defined by physical and protocol specifications per ATM Forum UNI documents. The
standard adopted by the ATM Forum to define connections between users or end
stations and a local switch.
VCI. See Virtual Channel Identifier (VCI).
Virtual Channel Identifier (VCI). A unique numerical tag as defined by a 16 bit field in the
ATM cell header that identifies a virtual channel, over which the cell is to travel.
Virtual Path Identifier. An eight bit field in the ATM cell header which indicates the virtual
path over which the cell should be routed.
VPI. See Virtual Path Identifier.
wide area network (WAN). A network that operates over a larger geographical area than
that provided by a LAN. The elements of a WAN may be separated by distances great
enough to require telephone communications. Contrast with local area network (LAN).
$ZZATM. See ATM Management Process (AMP).