DCP Series Telcon Message Manual - Public Support Login - Unisys

Glossary
OSI Reference Model
The seven-layer architectural model, defined by the International Organization for
Standardization (ISO), that provides the framework for building an open network. The
seven layers include: application, presentation, session, transport, network, data link, and
physical.
P
Packet Switched Communications Software (PSCS)
PSCS is one of the program products from the Open Systems products available for
Telcon. It enables communication between DCPs and other devices attached to packetswitched
PDNs. It also enables point-to-point connections using the Recommendation
X.25 protocol defined by the Consultative Committee on International Telephone and
Telegraph (CCITT). See also X.25 Packet-Switched Communications Software.
packet-switched network
A network based on packet-switching technology in which data is transmitted in units
called packets. Messages are split into packets, then routed independently on a
store-and-forward basis and reassembled at the receiving end of the communication link.
Packet-switched data transfer uses the communication link only during the time of actual
transmission.
PCALL
PDCNMS
PDN
PDN28I
PDNETP
The X.25 call processing handler. This procedure is defined in X.25 PSCS element
PDNCALL. It processes call packets received from the network or call primitives
received from a level 4 program using the Layer 3/4 Platform.
The X.25 Common Network Management Services (CNMS) interface handler. This
procedure is defined in X.25 PSCS element PDNSVS. PDCNMS processes commands
received from the CNMS manager through the Telcon Manager-Agent User (MAU) and
collects attribute, alarm, or statistics information from other X.25 PSCS modules. This
procedure collects CENLOGs of various events that occur in other X.25 PSCS modules.
See public data network.
The nonfunctional version of the X.28 PAD terminal handler interface. This procedure is
defined in Telcon and is present only when X.25 PSCS is not installed.
Implements the X.25 DCE Network feature, which allows one or more Telcon processors
to be an X.25 network. This procedure is defined in both the nonfunctional Telcon
element PDNPAD and in the X.25 PSCS element PDNNET. The nonfunctional procedure
is present only when X.25 PSCS is not installed. This feature allows an X.25 DTE device to
directly attach to a DCP and form a packet-level connection to any other attached X.25
DTE device. Also provides “internal DTE” interfaces to some of the level 4 programs using
the Layer 3/4 Platform in X.25 PSCS.
Glossary–12 7436 0728–303