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Communications Architecture For Layered Open Systems

Objective

The goal of the CARLOS project was to allow users of PCs and terminals to access X.25 and X.75 data networks and to provide them with value-added services conforming to Open Systems Interconnection (OSI) standards. The services involved were file transfer(FTAM), X.400 message-handling, virtual terminal (VT) emulation and network management.
The goal of the communications architecture for layered open systems (CARLOS) project was to allow users of personal computers (PC) and terminals to access X.25 and X.75 data networks and to provide them with value added services conforming to open systems interconnection (OSI) standards. The services involved were file transfer (FTAM), X.400 message handling, virtual terminal (VT) emulation and network management.
Various OSI components were developed during the project: the OSI-PAD and the OSI-BOX (later combined in the extended OSI-PAD), allowing nonOSI terminals to access (using the VT protocols) OSI conformant applications over X.25 networks; and the OSI-PC, implementing all 7 layers of the OSI model and giving PC users access to both the VT and FTAM services. The network management centre (implemented on a Unix based system) provides a comprehensive network management service for control, monitoring, fault detection and correction of heterogeneous distributed OSI network resources. This control centre is enriched with a set of generalized tools for the presentation of the information in a graphical way, providing a flexible and user friendly means for network operation and management.
There have been 2 extensions to the project: CACTUS (CARLOS addition for clustered terminal user agents) which allows a low cost connection of PC to the X.400 world and SESTA (standard European strategic programme for research and development in information technology (ESPRIT) system transfer adaptor), which adds OSI support to the industry standard PC-AT.
Various OSI components were developed during the project: the OSI-PAD and the OSI-BOX (later combined in the extended OSI-PAD), allowing non-OSI terminals to access (using the VT protocols) OSI conformant applications over X.25 networks; and the OSI-PC, implementing all 7 layers of the OSI model and giving PC users access to both the VT and FTAM services. The Network Management Centre (implemented on a Unix-based system) provides a comprehensive network management service for control, monitoring, fault detection and correction of heterogeneous distributed OSI network resources. This control centre is enriched with a set of generalised tools for the presentation of the information in a graphical way, providing a flexible and user-friendly means for networkoperation and management.
There have been two extensions to the project:
CACTUS (CARLOS Addition for Clustered Terminal USer agents), which has developed CCITT X.400 message-handling software for a cluster of PCs around a central server. The central server contains the message transfer agent (MTA) which communicates to other MTAs via the P1 and P2 protocols and the user mailboxes. The PC contains a user interface, a mailbox client and the underlying communication software needed to connect to the central server (using the P7 protocol). This method of working allows a low cos t connection of PCs to the X.400 world.
SESTA (Standard ESPRIT System Transfer Adaptor), which adds OSI support to the industry-standard PC-AT. Whereas during the CARLOS project the OSI-PC was implemented on an RC750 Partner microcomputer running concurrent Dos, SESTA wanted to provide the same functionality on an AT-bus compatible adaptor board. This OSI board can connect any AT-compatible PC to an X.25 WAN. FTAM and VT were implemented as value-added services. The PC user can access these services via an easy-to-use window-driven interface.Exploitation
Case Communications has already used know-how acquired during the CARLOS project to provide X.25 PAD facilities to their DCX product range, and is now planning to use the CACTUS work as the basis for the addition of an X.400 message server. RC International is planning commercial products based on the SESTA work. INESC and the Universidad Politecnica de Madrid and Barcelona are heavily involved in work related to the research networks in Portugal and Spain, as well as in the Eureka COSINE project (which is building a pan-European OSI-conformant research network). Knowledge acquired during the CACTUS and SESTA projects is part of the basis for such work, and many of the components developed during the CARLOS project will be reused.

Coordinator

PMC
Address
Square Ambiorix 17
1040 Bruxelles
Belgium

Participants (7)

Case Communications Ltd
United Kingdom
Address
Caxton Way Watford Business Park
WD1 8XH Watford
FISCHER MADSEN & LORENZ PETERSEN A/S
Denmark
INESC
Portugal
PMC APS
Denmark
RC INTERNATIONAL A/S
Denmark
UNIVERSIDAD POLITECNICA DE CATALUNA
Spain
UNIVERSIDAD POLITÉCNICA DE MADRID
Spain