SWAN Concentrator and WAN Subsystem Troubleshooting Guide

Glossary
SWAN Concentrator and WAN Subsystem Troubleshooting Guide—426992-008
Glossary-4
data communications equipment (DCE)
data communications equipment (DCE). Equipment that provides all the functions
required to establish, maintain, and terminate a connection and provides the signal
conversion and coding between the data terminal equipment (DTE) and telephone
company lines or data circuits. A DCE is usually a modem.
data link control (DLC) task. Tasks that support the equivalent to Layer 2 of the Open
Systems Interconnection (OSI) reference model. Wide area network (WAN) DLC tasks
run in the SWAN concentrator communications line interface processor (CLIP), and
each WAN DLC task controls one line interface. More than one type of DLC task can
run in the same CLIP. Two DLC tasks run in each CLIP.
data terminal equipment (DTE). Equipment that constitutes the data source or data sink
and provides for the communication control function protocol; DTE includes any piece
of equipment at which a communication path begins or ends. The SWAN and SWAN 2
concentrators are DTEs that connect to a modem. See also modem.
DEVICE object. A configurable object within the WAN subsystem SCF interface that
represents a data communications subsystem object.
download. The process of transferring files from disk storage on the NonStop S-series
server into the CLIP. See also communications line interface processor (CLIP) and
FIRMUP.
download module (DLM). Deprecated term for a module containing code that can be
downloaded from a file on the server into the CLIP memory. See also communications
line interface processor (CLIP).
dynamic random memory (DRAM). The bulk of the SWAN concentrator CLIP memory is
DRAM, which must be refreshed every few milliseconds or its contents are forgotten.
See also random access memory (RAM).
EnvoyACP/XF subsystem. When combined with a communications-oriented user
application, EnvoyACP/XF supports connection with specialized bit-synchronous
devices not supported by higher-level HP communications products. EnvoyACP/XF
provides an OSI Layer 2 interface between transaction-oriented applications and data
communications lines. ENVOYACP/XF supports three bit-synchronous protocols:
SDLC, HDLC, and ADCCP. See also Open Systems Interconnection (OSI).
error-recovery. Part of the implementation of a data communications protocol that permits
detection of errors in data transmission and assists in retransmission of that data or in
operations on the received data in error. See also protocol.
Ethernet. A form of local area network (LAN). The Ethernet data transfer rate is typically 10
or 100 Megabits per second (Mbps).
Expand network. The Expand network software extends NonStop operation to networks of
geographically distributed NonStop systems. With Expand, authorized users can use
processes, files, or devices on any system in the network, regardless of their physical
location or the occurrence of a line or component failure.