OSI/TS Configuration and Management Manual

Glossary
OSI/TS Configuration and Management Manual—424831-001
Glossary-15
TSDU (transport service data unit).
TSDU (transport service data unit). A unit of data used by transport peer entities to
transfer data.
TSEL (transport selector). A logical address in the Transport Layer through which
transport services are made available. A single TSEL can service one or more
connections simultaneously.
TSP (transport service provider) process. A process in the OSI end system that performs
service and protocol functions for the Transport Layer and for the internet protocol (IP)
of the Network Layer. TSP processes are provided by the underlying OSI/TS
subsystem.
Typed data. Data sent over a Session Layer connection regardless of the location of the data
token. Under some circumstances, protocol data units from the Session Layer and the
Application Layer may need to be sent as typed data. The typed data functional unit
must have been negotiated for the connection.
X.25 network. Any network or subnetwork linked using X.25 standards. X.25 standards
are CCITT standards that define packet switching carrier communication in the Network
Layer over wide area networks (WANs).
X25AM (X.25 Access Method). A Compaq product that implements, for WANs, the
services of the Network Layer and layers below.