Network Overview and Concepts

Network

Overview and Concepts ASCALE 7000 DPS7000/XT NOV

Communications: FCP7

REFERENCE 47 A2 92UC 03

DPS7000/XTA NOVASCALE 7000 Network Overview and Concepts

Communications: FCP7

August 2002

BULL CEDOC 357 AVENUE PATTON B.P.20845 49008 ANGERS CEDEX 01 FRANCE

REFERENCE 47 A2 92UC 03 The following copyright notice protects this book under Copyright laws which prohibit such actions as, but not limited to, copying, distributing, modifying, and making derivative works.

Printed in France

Suggestions and criticisms concerning the form, content, and presentation of this book are invited. A form is provided at the end of this book for this purpose.

To order additional copies of this book or other Bull Technical Publications, you are invited to use the Ordering Form also provided at the end of this book.

Trademarks and Acknowledgements We acknowledge the right of proprietors of trademarks mentioned in this book.

Intel® and Itanium® are registered trademarks of Intel Corporation.

Windows® and Microsoft® software are registered trademarks of Microsoft Corporation.

UNIX® is a registered trademark in the United States of America and other countries licensed exclusively through the Open Group.

Linux® is a registered trademark of Linus Torvalds.

The information in this document is subject to change without notice. Bull will not be liable for errors contained herein, or for incidental or consequential damages in connection with the use of this material. Preface

Scope and This manual gives an overview of communications architecture for the DPS 7000. Objectives Communications architecture is dealt with essentially in three parts:

• ISO-DSA communications • ISO communications • TCP/IP communications The discussion is about communications applicable to Bull systems, and in particular, communications as implemented for the DPS 7000.

Bibliography The following documents may be consulted for further information on the main topics referred to in this manual.

Datanet and CNP7: DNS V4 System Generation ...... 39 A2 22DN CNS 7 System Generation...... 39A2-40DM

Transport and Session Servers: VCAM-ISO Reference Manual (Part 1)...... 47 A2 60UC VCAM-ISO Reference Manual (Part 2: Primitives) ...... 47 A2 61UC VCAM-ISO User’s Guide...... 47 A2 62UC

Network Installation, Operation and Administration: Getting Started with your Telecommunications ...... 47 A2 70UC Network Generation...... 47 A2 93UC Network User Guide ...... 47 A2 94UC DSAC User’s Guide ...... 47 A2 75UC AUPI User’s Guide ...... 47 A2 76UC

47 A4 92UC Rev03 iii Network Overview and Concepts

Service of Correspondents: Transactional Intercommunication using XCP1 User’s Guide...... 47 A2 11UT CPI-C/XCP2 User’s Guide ...... 47 A2 14UT TDS Administrator’s Guide...... 47 A2 20UT

MainWay and MainWay 2600LE Documents: MainWay Overview...... 39 A2 14EB MainWay 2600LE User’s Guide...... 39 A2 60AE MainWay 2600LE HW, SW & Maintenance Guide...... 39 A2 61AE MainWay 2600 Site Preparation Guide ...... 39 A1 82RA

DPS 7000 to XTA Evolution Guide: V7000 Operator’s Guide...... 47 A2 74US V7000 Configuration and Maintenance Guide...... 77 A2 77US V7000 Software Installation and Activation Guide ...... 77 A2 88US GCOS7 - System Installation Configuration and Updating Guide...... 47 A2 23US GCOS7-V10 System Operator’s Guide...... 47 A2 53US DPS 7000/XTA Interop 7 User’s Guide...... 47 A2 91US GCOS 7 Console Messages Directory...... 47 A2 61UU GCOS 7 Messages and Return Codes Directory ...... 47 A2 10UU

Other Documents: INET Reference Manual ...... 13 A2 12SM INET User Guide ...... 13 A2 13SM MCS User’s Guide ...... 47 A2 32UC TCP/IP 7 End-User’s Guide ...... 47 A2 30US OPEN 7 Administrator’s Reference Manual...... 47 A2 31US OPEN 7 Administrator’s Guide ...... 47 A2 32US

GCOS 7 Documentation The complete GCOS 7 document set is available on one CD-ROM. This product is known as CD-DOC. It is delivered with each system or software update, it is updated for each new GCOS 7 release. A WEB site is available to download documents which have been updated between 2 CD-ROM versions, its URL is indicated as a link on the CD-ROM itself.

iv 47 A4 92UC Rev03 Preface

Syntax The following notation conventions are used in this manual when describing the Notation syntax of commands: UPPERCASE The keyword item must be coded exactly as shown. Lowercase Indicates a user-supplied parameter value. The symbolic name digits is used to represent a string of decimal digits of maximum length n. [item] An item within square brackets is optional. {item 1} A column of items within braces means that one value must {item 2} be selected if the associated parameter is specified. {item 3} The default value (if any) is underlined. ( ) Parentheses must be coded if they enclose more than one item. . . . An ellipsis indicates that the preceding item may be repeated one or more times.

47 A4 92UC Rev03 v Network Overview and Concepts

vi 47 A4 92UC Rev03 Table of Contents

1. Introduction

1.1 DPS 7000 Communications Environments...... 1-1 1.2 Communications Features of GCOS 7...... 1-2 1.3 DPS 7000 Communications Architecture...... 1-3 1.3.1 MainWay 2600, Datanet, and CNP7...... 1-6 1.3.2 ISL Controller ...... 1-6 1.3.3 FCP7 and VCP7 Controllers...... 1-7 1.3.3.1 FCP7 Controller...... 1-7 1.3.3.2 VCP7 Controller...... 1-7 1.3.4 MainWay 2600 ...... 1-8 1.3.5 MainWay 2600LE for DPS 7000/XTA...... 1-8 1.4 Communications Servers ...... 1-9 1.5 VCAM ...... 1-10 1.6 OPEN LAN ACCESS 7 ...... 1-10 1.7 GXTI ...... 1-10 1.8 RFC1006 ...... 1-11 1.9 TCP/IP...... 1-11 1.10 Network Configuration...... 1-11 1.11 Network Administration ...... 1-12

2. ISO/DSA and ISO Communications

2.1 Concepts of a Layered Architecture...... 2-2 2.2 ISO and ISO/DSA Layers Implementation...... 2-3 2.3 DSA Addressing...... 2-10 2.4 OSI Addressing Concepts...... 2-13 2.4.1 General Structure...... 2-14 2.4.2 Network Layer Addressing: NSAP Address...... 2-15

47 A4 92UC Rev03 vii Network Overview and Concepts

2.4.3 Transport Layer Addressing: TSAP Address...... 2-20 2.4.4 Session Layer Addressing: SSAP Address ...... 2-21 2.4.5 Presentation Layer Addressing: PSAP Address...... 2-21 2.4.6 Application Layer Addressing: AET ...... 2-21 2.4.7 Default Local Addresses...... 2-22 2.5 OPEN LAN ACCESS: ISO/DSA PLUG...... 2-23 2.5.1 ISO - DSA Plug Functions ...... 2-23 2.5.2 Protocol Conversion Mechanism ...... 2-24 2.5.3 Address Conversion Mechanism ...... 2-25 2.5.4 Examples of Network Configurations...... 2-27 2.6 Use of TNS Extension for ISO Sessions...... 2-29 2.7 Use of FEPS for ISO sessions...... 2-29 2.8 Use of OCS for ISO sessions...... 2-29 2.9 Connection Mechanism...... 2-30 2.9.1 ISO/DSA Session Connection Mechanism...... 2-30 2.9.1.1 Introduction...... 2-30 2.9.1.2 Outward Connection Mechanism ...... 2-30 2.9.1.3 Inward Connection Mechanism ...... 2-32 2.9.2 ISO Session Connection Mechanism ...... 2-32 2.9.2.1 Introduction...... 2-32 2.9.2.2 Outward Connection Mechanism ...... 2-32 2.9.2.3 Inward Connection Mechanism ...... 2-35 2.9.3 FEPS Pseudo-Transport...... 2-35 2.9.3.1 Inward Connections...... 2-35 2.9.3.2 Outward Connections...... 2-36 2.9.4 TNS Connections...... 2-37 2.9.4.1 Outward Connections...... 2-37 2.9.4.2 Inward Connections...... 2-38 2.9.5 OCS Connections ...... 2-40 2.9.5.1 Outward Connections...... 2-40 2.9.5.2 Inward Connections...... 2-41 2.10 Direct Interfaces to Communication Layer...... 2-42 2.10.1 Transport Interface...... 2-42 2.10.2 Session Interface ...... 2-42

3. TCP/IP Communications

3.1 TCP/IP Layered Architecture ...... 3-1 3.2 TCP/IP Addressing Concepts ...... 3-4 3.2.1 IP Addresses...... 3-4 3.2.2 MAC Addresses...... 3-6

viii 47 A4 92UC Rev03 3.3 TCP/IP Implementations on GCOS 7...... 3-7 3.3.1 TCP/IP via FCP7...... 3-7 3.3.2 TCP/IP via OPEN7...... 3-9 3.3.3 TCP/IP via INTEROP7...... 3-11

4. GCOS 7 View of the Network

4.1 Describing the Network ...... 4-1 4.2 NETGEN Utility...... 4-2 4.2.1 Network Description...... 4-2 4.2.2 Network Configurations...... 4-3 4.3 OCS Front End Configuration ...... 4-5

5. GCOS 7 Network Administration

5.1 ISO/DSA and ISO Administration...... 5-1 5.2 IPS Administration...... 5-1 5.3 OCS Front End Management...... 5-2 5.4 Administrative Function for FEP’s ...... 5-2 5.5 Administrative Function for MainWay 2600LE ...... 5-2

Glossary

Index

47 A4 92UC Rev03 ix Network Overview and Concepts

Table of Graphics

Figures 1-1. Communications Architecture for DPS 7000 ...... 1-4 1-2. Communications Architecture for DPS 7000/XTA ...... 1-5 2-1. DSA/ISO Layers...... 2-2 2-2. DSA/ISO Layer Implementation on DPS 7000 ...... 2-3 2-3. DSA/ISO Layer Implementation on DPS 7000/XTA ...... 2-4 2-4. ISO Transport Connection ...... 2-7 2-5. DSA Applications Communicating via the RFC1006 Transport...... 2-8 2-6. DSA/ISO Communications Controller ...... 2-9 2-7. DSA/ISO Address Configuration...... 2-12 2-8. OSI PSAP Address Structure...... 2-14 2-9. OSI NSAP Address Structure ...... 2-15 2-10. AFI Values in OSI NSAP Address...... 2-16 2-11. DSP Values in OSI NSAP Address...... 2-17 2-12. Field Lengths in OSI NSAP Address...... 2-18 2-13. Example of RFC1006 NSAP Address Format ...... 2-20 2-14. ISO-DSA Plug (PID) Functions ...... 2-24 2-15. Examples of TSELs in the DPS 7000 ...... 2-26 2-16. Two Systems with the Same TSEL...... 2-26 2-17. Two Systems with Different TSELs...... 2-27 2-18. PIDp Generation Example ...... 2-27 2-19. PIDa Generation Example ...... 2-28 2-20. ISO Quality of Service...... 2-34 3-1. TCP/IP Layered Architecture ...... 3-1 3-2. IP Address Format ...... 3-4 3-3. TCP/IP via FCP7...... 3-7 3-4. TCP/IP Access via OPEN7 ...... 3-9 3-5. TCP/IP via INTEROP7 for DPS 7000/XTA ...... 3-12

x 47 A4 92UC Rev03 1. Introduction

Bull GCOS 7 communications software provides the means to communicate with other GCOS or non-GCOS systems via a local or a long-distance network. This manual gives an overview of the communications components of GCOS 7.

1.1 DPS 7000 Communications Environments

The Bull DPS 7000 can be accessed in the following different environments:

• The Bull world in communication with other Bull systems such as GCOS 7, GCOS 8 or AIX platforms • The OSI world as DPS 7000 supports OSI communication protocols • The UNIX world, with regards especially to TCP-IP features • The IBM world in communication with IBM systems • The Windows and NT world in communication with workstations or servers DPS 7000 communication environment can use directly the ISL (Inter-System Link), or use Communication Processors with FDDI or High speed Ethernet adapters, or require one or several FEP (Front End Processors) and Communication Controllers to manage terminals or stations and provide gateways to any of the above-listed network environments.

47 A4 92UC Rev03 1-1 Network Overview and Concepts

1.2 Communications Features of GCOS 7

The main features of GCOS 7 communications are:

• Full support of ISO/DSA network • Full support of OSI network • Full support of TCP/IP network either directly or thru the Interop7 mechanisms • Direct access to Ethernet local area network • Direct access to FDDI local area network • Direct support of the DIWS (“ DSA/ISO Workstation ”) alias STID (“ Station de travail ISO/DSA ”), which is a station executing DSA application on the OSI session • Availability of OSI session programmatic interface • Availability of GXTI programmatic interface (GCOS7 X/OPEN Transport Interface) • Support of LU6.2 connections (XCP2 module) through the DSA-SNA gateway or directly to such XCP2 implementations as CPI-C/OSI on AIX • Support of previous functionalities such as XCP1, MCS,… • Support of OSI/DSA sessions over TCP/IP layers (RFC1006) via OCS (Open Communication Subsystem).

1-2 47 A4 92UC Rev03 Introduction

1.3 DPS 7000 Communications Architecture

The DPS 7000 communication environment may require one or several front End Processors (FEP) to manage terminals, stations and/or to access networks. Since terminals are managed by the FEP, they are not declared in the DPS 7000 network generation but, instead, they are declared in the system generation (SYSGEN) of the FEP itself.

Three kinds of FEP are available:

• Datanet which is connected to the DPS 7000 over a PSI channel • CNP7 which is either integrated in or connected as an extension to the DPS 7000 • MainWay (current Bull offer) which is connected to the DPS 7000 thru an OCS connection which is either FDDI or fast Ethernet

DPS 7000 communication environment allows also direct access to Local Area Networks , without making use of FEP’s, when the FEP’s specific functions are not used (such as gateways, terminal manager …)

• On DPS 7000 running Bull CPU’s, 2 types of direct access are available: − Access thru ISL controller to stations, systems and communication processors via 10 Mbits Ethernet − Access thru OCS controller to stations, systems and communication processors via 100 Mbits FDDI • On DPS 7000 running commodity CPU’s: Access thru OCS controller to stations, systems and communication processors via Local area Network (e.g.: Fast Ethernet)

DPS 7000 communications are handled by software modules named communication servers, as described below: • Figure 1-1 shows the basic communication architecture for DPS 7000 • Figure 1-2 shows the basic communication architecture for DPS 7000/XTA

47 A4 92UC Rev03 1-3 Network Overview and Concepts

Figure 1-1. Communications Architecture for DPS 7000

1-4 47 A4 92UC Rev03 Introduction

DPS 7000/XTA

GCOS7 GCOS7 applications using the telecommunications

VCAM (session layer) Open LAN Access SOCKG7 (PID)

OCS

EXTENDED VIRTUAL VCP7 VCP7 VIRTUAL MACHINE MACHINE (telecom 1 to 4 VCP7 transport & network protocols)

TCP/IP Driver

Ethernet COMMODITY SOFTWARE Ethernet Ethernet Controller Controller Controller

Fast Ethernet MAINWAY

Primary Network Local Area Networks Secondary Network

Figure 1-2. Communications Architecture for DPS 7000/XTA

47 A4 92UC Rev03 1-5 Network Overview and Concepts

1.3.1 MainWay 2600, Datanet, and CNP7

The DPS 7000 can connect to the network through:

• a MainWay 2600 and its LAN Extender via the OCS server module and an FDDI SAS link, • a Datanet via the FEPS server module and a PSI channel, • a CNP7 via the TNS server and a controller accessing the ISL by means of an Ethernet link. The controller is one of the following:

• the SPA (DPS 7000/2xx/3xx), • the MPC (DPS 7/1x07/10x7/5x0/7x0x), • the LNM (DPS 7000/Ax), • the LNI (DPS 7000/4xx), • the FIA (Fast ISL Access) option in the DPS 7000/5xx /7xx /8xx. There is one controller board per physical attachment of the DPS 7000 to an ISL cable.

1.3.2 ISL Controller

The ISL controller also allows the DPS 7000 to connect directly over an Ethernet link to another DPS 7000, another DSA, ISO/DSA or TCP/IP system. The ISL complies with IEEE 802.3 and ISO 8802.3 (Ethernet) specifications. These connections are managed by the TNS server.

1-6 47 A4 92UC Rev03 Introduction

1.3.3 FCP7 and VCP7 Controllers

1.3.3.1 FCP7 Controller

FCP7 is a Bull FDDI controller located in the DPS 7000 cabinet.

OCS Driver FCP7 interfaces with the DPS 7000 via the OCS driver through an MB2 (Multibus 2) and connects to an FDDI network by means of an FDDI SAS link. FCP7 handles the four first layers of DSA and OSI communications (transport, network, link and physical layers) and TCP/IP layers. FCP7 supports the RFC1006 layer to enable OSI/DIWS sessions to run over TCP/IP protocols.

Optical Loopback Plug Each FCP7 controller is delivered with an optical loopback plug already mounted. This plug is used during OLTD tests. The plug also serves as an anti-dust protector when the controller is not attached (to a fiber optic cable).

Address Label Each FCP7 controller has a stick-on label on which its MAC address can be written. This address is not related to the controller’s serial number. FCP7 MAC addresses are in the range 08 00 38 10 00 10 to 08 00 38 10 0F DF. Once the MAC address has been assigned, it should be written on the label. The label is then stuck on the appropriate DPS 7000 rack (in which the FCP7 is placed).

1.3.3.2 VCP7 Controller

On a DPS 7000/XTA, FCP7 controller is replaced by a virtual controller: VCP7, which handles Transport and Network communication layers in the same way as they are handled by FCP7 on a DPS 7000, and executing with the addition of an Adapter card and its associated driver, the same set of communication functions, as these globally executed by FCP7.

47 A4 92UC Rev03 1-7 Network Overview and Concepts

1.3.4 MainWay 2600

The MainWay 2600 includes the LAN Extender Subsystem and one or more WAN Processor Modules giving access to the WAN network via either OSI/DSA, OSF/SNA, or TCP/IP protocols.

1.3.5 MainWay 2600LE for DPS 7000/XTA

The MainWay 2600LE offer is available on DPS 7000/XTA. It can replace the low- cost CNP7/CNS A2, or the Datanet 7500 Entry modules for DPS 7000. The MainWay 2600LE includes a µLAN Extender for LAN links, a FEP called WNP and a Line Module for the WAN links. The MainWay 2600LE provides the OSI/DSA support, the X21/X25 network support and the BSC support. But it does not support the TCP/IP links. It is administrated from DPS 7000/XTA system.

1-8 47 A4 92UC Rev03 Introduction

1.4 Communications Servers

The main communications functions are handled by communications servers which are implemented as independent subsystems. The communication servers are:

• TNS, a unique server that handles communications over one or several ISL controllers, allowing communications over one or several ISL cables. There is only one occurrence of TNS in a DPS 7000 system. TNS manages all connections with other systems either directly or through CNP7. The TNS configuration parameters are specified at network generation. • FEPS, a server that handles the dialog with a Datanet through 1 or 2 PSI channels. There is one occurrence of FEPS in a DPS 7000 system for each Datanet attached. In the case of a bi-PSI link towards a single Datanet, only one PSI channel is managed by the FEPS occurrence at a time, the other occurrence being backup. FEPS manages the two PSI links so that it automatically, restarts in a transparent way on the other PSI when the first fails. Each FEPS occurrence must be defined at network generation. • OCS is the communication driver which is common to DPS 7000 and DPS 7000/XTA, it drives as well FCP7’s as VCP7’s depending upon the DPS 7000 platform. OCS is a single driver which handles up to 4 server instances (one per OCS Front End). OCS also performs administrative functions for OCS Front End such as memory dump (DUMP) or load (LOAD). The OCS configuration parameters are specified at network generation. • FECM, a server that performs administrative functions such as LOAD, DUMP or SYSGEN for the Datanet and the CNP7. It does not need to be configured and an occurrence of FECM is dynamically created when a Datanet or a CNP7 is to be administered. • RAEH, a unique server that handles administrative sessions between DSA systems for the purpose of exchanging commands/responses or event notifications. • QMON, a unique server that manages queues accessed by applications using the MCS communications interface.

47 A4 92UC Rev03 1-9 Network Overview and Concepts

1.5 VCAM

VCAM is a communications module which handles the functions dealing with the session layer (connections between local or remote applications using ISO ISO/DSA or DSA protocols and addressing). Starting and terminating this communications module is synchronized with those of GCOS 7 itself. But only local connections can be done while no communications session is active.

1.6 OPEN LAN ACCESS 7

OPEN LAN ACCESS 7 is a communications module which handles the protocol and/or address conversion from DSA to ISO. This mechanism allows DSA applications such as IOF, TDS, UFT to work with applications located in an ISO/DSA workstation (DIWS). Use of OPEN LAN ACCESS 7 is defined in network generation.

1.7 GXTI

GXTI is a programmatic interface which allows a GCOS 7 application to access a remote application through ISO transport, TCP or UDP transport, or RFC1006 transport. It supplies a unique communication interface:

• with remote applications through the ISO transport located in the OCS Front End, • with remote ISO/DIWS applications through the RFC1006 transport located in the OCS front ends (without programmatic interface modification), • with remote applications through the ISO transport located in a Datanet via FEPS, • with remote applications through the ISO transport located in a CNP7 via TNS, • with remote applications through the TCP or UDP transport located in OCS front ends, • with remote applications through the TCP or UDP transport located in the OPEN7 subsystem. Note that access to TCP/UDP from FCP7 and OPEN7 are mutually exclusive in the sense that one cannot establish connections from TCP to OPEN7 and to FCP7, but both can be launched simultaneously. In such a case, FCP7 has priority. If the GXTID daemon under OPEN7 is launched before FCP7, FCP7 stops GXTID to force the connections to pass via FCP7. If FCP7 is launched before OPEN7 (and therefore before GXTID), FCP7 has priority.

1-10 47 A4 92UC Rev03 Introduction

1.8 RFC1006

RFC1006 is an inter-layer protocol available in OCS Front End which allows DSA or OSI to run through a TCP transport. RFC1006 complies with the procedure and TPDU format defined in ISO IS 8073.

1.9 TCP/IP

TCP/IP allows GCOS 7 applications to reach remote applications on a UNIX or TCP/IP station. TCP/IP is available in the OCS front ends for applications using the GXTI programmatic interface and in OPEN 7 for applications such as FTP, NFS, XFORM 7, Affinity on OPEN 7. TCP/IP (of the OCS front ends) is also used to carry the RFC1006 TPDUs for GCOS 7 applications.

1.10 Network Configuration

Under GCOS 7, the generation utility used for the network configurations is NETGEN (NETwork GENerator). NETGEN is described in the manual Network Generation. An OCS Front End is configured each time its OCS server is started (STSVR command). This configuration loads the parameters necessary for the communication protocols handled by the OCS Front End. The OCS Front End configuration is described in the manual Network Generation. The Datanet and the CNP7 need to be configured through their own configuration tools. These tools are described in the Datanet or CNP7 manuals. Network configurations directives for DPS 7000 and its FEPs are statically generated by their respective configurators from descriptive information entered by the network (or system) administrator. The following terminology is adopted throughout the documents: DIRECTIVE any statement appearing in a network configuration description which can be processed by a network configurator.

47 A4 92UC Rev03 1-11 Network Overview and Concepts

1.11 Network Administration

Network administration allows a network (or system) operator to handle local functions such as starting or terminating the servers, to survey the behavior of the network and to modify dynamically network attributes through network administration commands. The following terminology is adopted throughout the documents: COMMAND any instruction addressing the operating system (GCOS 7 for the DPS 7000) keyed in by the network (or system) operator.

1-12 47 A4 92UC Rev03 2. ISO/DSA and ISO Communications

The OSI reference model of ISO defines a basic software architecture of communications, based on layered functions. DSA defines a layered architecture which complies with the OSI reference model of ISO. This means that the concept of a layered architecture and the role of each layer are common to DSA and ISO. Depending on each layer, GCOS 7 implements either the ISO standard for the layer or a proprietary Bull DSA standard.

47 A4 92UC Rev03 2-1 Network Overview and Concepts

2.1 Concepts of a Layered Architecture

According to the OSI reference model, the communication subsystems of a system can be considered as an ordered set of seven layers which can be visually represented as the vertical sequence shown below. The layer takes also the name of its rank.

Layers System A System B Application 7 <-protocol-> 7 Presentation 6 <-protocol-> 6 s s Session e 5 <-protocol-> 5 e r r Transport v 4 <-protocol-> 4 v i i Network 3 <-protocol-> 3 c c Data Link e 2 <-protocol-> 2 e Physical 1 <-protocol-> 1 Physical Media

Figure 2-1. DSA/ISO Layers Except for the highest or lowest layers, each (N)-layer provides the (N+1)-layer with a set of services. The (N)-layer in turn uses the services provided by the (N-1) layer, and so on. Addressability of each layer services is given through (N)-SAPs (Service Access Points). Each (N)-layer entity co-operates with its (N)-layer peer in another system. The set of rules governing this co-operation is termed protocol and is associated with the layer for which it is implemented. The data exchanged when implementing the protocol of the concerned layer is its PDU (Protocol Data Unit). Such architecture ensures that each layer and also application is independent of all subsequent subsystems implementing the lower ISO layers. For GCOS 7, the layers 1 to 5 protocols and services fully comply with ISO standards as well as the DSA standard.

2-2 47 A4 92UC Rev03 ISO/DSA and ISO Communications

2.2 ISO and ISO/DSA Layers Implementation

Figure 2-2. DSA/ISO Layer Implementation on DPS 7000 Modules shaded / / / concern the front-end processors, not GCOS 7.

47 A4 92UC Rev03 2-3 Network Overview and Concepts

Figure 2-3. DSA/ISO Layer Implementation on DPS 7000/XTA

2-4 47 A4 92UC Rev03 ISO/DSA and ISO Communications

Application Layer The application layer is the highest (7) layer in the Reference Model. It provides services which are directly accessible to the user.

The primary network consists of ISO/DSA applications which communicate with each other as peers. Examples of DSA applications are IOF, TDS and UFT. Applications co-operate with terminals using a different mechanism.

Terminals do not implement ISO/DSA protocols and therefore cannot directly co- operate with applications. Instead, terminals use the Terminal Manager which functions as a relay application residing in the FEP or in a DSA/ISO Workstation, to communicate with applications. The part of the network between the terminal manager and the terminals (secondary network) does not comply with the ISO/DSA standard. For example MainWay 2600 as session endpoint provides the support of Terminal manager for accessing terminals.

Presentation Layer The Presentation layer (6) is concerned with the conversions and formatting to be applied to the contents of data exchanged between applications. Presentation functions are often embedded in system software or firmware such as ASCII-to-EBCDIC conversion. They can also apply to specific products such as FORMS for handling the display of information on the terminal screen.

Session Layer The Session layer (5) organizes and synchronizes the dialog between two applications. It establishes connections, manages the flow of data exchanged, and controls the turn (token) among session endpoints. A session connection can be established by the session layer between two applications residing in different systems or in the same system. In the latter case, such a session connection is local and does not involve transport. Connection and message exchange between the applications pass through VCAM. However, when applications reside in different systems, the session layer uses the transport services to exchange messages between the systems. Depending on the application, VCAM implements the ISO or DSA protocols and services of the session layer. One part of VCAM implements the ISO session protocol and services while another part implements the DSA session protocol and services.

47 A4 92UC Rev03 2-5 Network Overview and Concepts

VCAM-DSA provides the interface for DSA applications such as TDS, IOF and UFT, executing in native Bull machines using DSA200 protocol. VCAM-ISO provides the interface for ISO applications such as FTAM and X400.

VCAM ensures that the application is independant of all lower layers. OPEN LAN ACCESS 7 provides a protocol conversion mechanism from an ISO session to a DSA session in order for a DSA remote application working over an ISO session (such as OPENTEAM, UFTX ... ) to dialog with a GCOS 7 DSA application (TDS, IOF, UFT ...). In addition to this protocol conversion, OPEN LAN ACCESS 7 provides an addressing conversion from ISO to DSA.

Transport Layer The Transport layer (4) assures a reliable transport for transferring data between sessions of different systems. Transport services control sequencing and flow of data, detect errors and provide recovery. Depending on the network configuration, a session connection maps onto either a single end-to-end transport connection or a sequence of transport connections relayed consecutively.

In the case of a connection thru OCS, the ISO class 4 protocol (ISO IS 8073) is implemented in the OCS Front End itself. Therefore ISO/DSA and ISO transport connections can be established with remote systems directly connected to the OCS Front End. In the case of a PSI connection to the Datanet, the transport layer is spread between FEPS and the Datanet. FEPS implements a pseudo-transport which is limited only to exchanges with the Datanet. The transport layer and all layers below it are implemented in the Datanet. It is the Datanet and not the DPS 7000, which is responsible for implementing the transport and network protocols in a communication with a remote system. In the case of an ISL connection, TNS implements the ISO class 4 transport protocol (ISO IS 8073). DSA and ISO/DSA transport connections (known as "DIWS" transport connections) can therefore be established with remote systems directly connected on the ISL. In the case of ISO transport connections, it is necessary to establish these connections through the ISO transport of a CNP7 (or Datanet) connected on the ISL.

2-6 47 A4 92UC Rev03 ISO/DSA and ISO Communications

The ISL can connect the FEP (CNP7 or Datanet) which functions as a relay in establishing the session between the DPS 7000 and a remote system. One transport connection ends in the FEP, while another transport connection is initiated between the FEP and the remote system. These two transport connections are directly linked (back-to-back transport). The transport connection between the FEP and the remote system may use a protocol different from that of ISO class 4 between the DPS 7000 and the FEP. This allows accessing systems which implement any combination of transport and network protocols supported by the FEP, on any kind of ISO network. Figure 2-4 shows a DPX/20 connected to a DPS 7000 via its CNP7.

DPS 7000 DPX/20

ISO sessionCNP 7 ISO session

ISO transport ISO transport ISO transport ISO transport

null network null network X25 X25

IEEE 802.2 IEEE 802.2 HDLC HDLC IEEE 802.3 IEEE 802.3

ISL · · ·

Figure 2-4. ISO Transport Connection

RFC1006 Transport Layer The RFC1006 transport layer is available only via OCS. It implements a class 0 transport protocol improved to run on top of TCP (which can be assimilated to a class 4 transport protocol). It uses elements of the procedure and the TPDU format defined in ISO IS 8073. Figure 2-4 shows DSA applications communicating via RFC1006.

47 A4 92UC Rev03 2-7 Network Overview and Concepts

Bull DPS 7000 Other System DSA Application DSA Application

DSA Presentation DSA Presentation DSA Session DSA Session RFC1006 RFC1006

TCP IPS Network TCP IP IP Link Link

Physical Physical

Figure 2-5. DSA Applications Communicating via the RFC1006 Transport RFC1006 supports communications between DSA applications (shown in the figure), or between OSI applications, or between DSA and OSI applications (through OLA7) via TCP transport.

Network Layer The Network layer (3) enables communications links to be established. Network services route the link through available intermediate systems, relay the information through the established link, and maintain the link for the duration of the user session. Figure 2-6 represents a typical network configuration with a relay system C interposed between Systems A and B, involving the network and lower layers. In ISO/DSA networks, such a relay system is usually a communications controller or FEP. In the case of an ISL connection, TNS implements a basic network layer referred to as the null subset of Internet (ISO IS 8473) which is also called inactive network. In the case of a connection via the OCS Front End. OCS Front End implements both the null subset and the full subset of Internet (ISO IS 8473) protocol. When the connections are established through a Datanet or a CNP7, the Network layer located in the FEP can be an inactive network, the full Internet protocol or other network protocol such as X25 (ISO 8348).

2-8 47 A4 92UC Rev03 ISO/DSA and ISO Communications

AB 7 7 6 6 5 5

4 C 4 3 3 3 2 2 2

1 1 1 Media Media

Figure 2-6. DSA/ISO Communications Controller

Data Link Layer The Data Link layer (2) provides a point-to-point transfer of individual frames of data over a physical connection. In the special case of a LAN (ISL or OCS), this layer is composed of the two following sublayers: 1. LLC (Logical Link Control) sub-layer which has a logical addressing capability 2. MAC (Media Access Control) sub-layer which interfaces with the physical layer by means of physical addressing.

Physical Layer The Physical layer (1) provides a mechanical, electrical, functional and procedural means to transmit bits. The ISL Ethernet controllers implement the link and physical layers (ISO IS 8802.2, 8802.3). The FCP7 FDDI controller implements the link and physical layers (ISO IS 8802.2, 9314).

47 A4 92UC Rev03 2-9 Network Overview and Concepts

2.3 DSA Addressing

A DSA application address is composed of the address of the session control to which it is attached and a local address associated with the session control entity. The address of a session control entity consists of the TSAP identifier and the SCID:

• A unique TSAP identifier for each session control entity within the network identifies it as a user of transport services. Both source and destination TSAP identifiers are only used by the ISO transport entity as part of the transport connection request protocol data unit, having the following characteristics: − the format of the TSAP identifiers conforms to the SID standard − when the transport is TNS, ISO transport with DSA addressing is the default declared by the TPROTOCOL=ISO[:1] parameter of the RTS directive. • The SCID which gives the address of the DSA session control used by the DSA200 session protocol to identify the session control in the session protocol data units. In DSA, the local address of an application is its mailbox. In order to be unique, the mailbox can be suffixed with a mailbox-extension. A communications application can be addressed through several mailboxes, each mailbox corresponding to a specific entity within the application. In TDS, for example, the master operator is addressed through a mailbox different from that dedicated to other users. Similarly, the Terminal Manager addresses a specific terminal by a unique address given by its mailbox:mailbox-extension. Lower layer entities also have addresses configured at Network Generation. In the case of communications through an FEP, such entities are not located within the DPS 7000 and are therefore configured in the SYSGEN of the FEP. On the other hand, when the ISL is involved in a direct connection to a remote system, additional addresses have to be considered. Dedicated LSAP (Link Service Access Point) addresses are used at Link level to separate the different kinds of traffic over the interface between TNS and the Local Network Adaptor. The LSAP is used by the ISL controller to choose a type of Logical Channel, also known as Logical Terminator (LT), for an incoming frame which must be directed to TNS.

2-10 47 A4 92UC Rev03 ISO/DSA and ISO Communications

TNS can address three different types of LSAP, namely: • ISO for normal data transfers through an inactive network layer • RM (remote maintenance) for maintaining the CNP7s (SYSGEN, LOAD and DUMP) using a specific administrative protocol • TCPIP for the TCP/IP module of GCOS 7 (OPEN 7) which uses the direct access in the Link-layer of TNS. A transport connection request is sent over a Network Route configured on the Local System which is seen as the source of the route going from the LPL (Local Physical Link) attached through the ISL cable to a RPL (Remote Physical Link). The LPL or RPL has an individual physical address (IADDR) on the ISL cable of 48 bits and must therefore be declared in the network configuration. Up to 8 MADDRs (Multicast Address) can be shared among different LPLs. These addresses are used to receive some specific broadcast messages over the cable for administration purposes.

In the case of communications thru OCS, these entities are configured in the NG and OCS configurations of the OCS Front End.

In the case of VCP7 the Medium Access Control address (MAC address) of the local area network adapter must be the same as the one declared in the NG configuration, this address can be reconfigured during the adapter card installation.

For OCS the Logical Terminators (LT’s) are implicitly generated by OCS.

47 A4 92UC Rev03 2-11 Network Overview and Concepts

Example of Address Configuration The example below illustrates two systems DPSA and DPSZ, each connected to its own CNP7 through an ISL cable, the CNP7s being interconnected to participate in a WAN (wide area network).

DPS 7000 CNP 7 CNP 7 DPS 7000 "DPSA" "CNPB" "CNPY" "DPSZ" 86:57 WAN 86:23

LCT RCT RCT LCT

CABLE-1 CABLE-2

ISLs 5E-00-01 5F-00-01 5F-00-02 5E-00-0C LPL_DPSA RPL_CNPB RPL_CNPY LPL_DPSZ

Figure 2-7. DSA/ISO Address Configuration Before application LAPPL running on the system DPSA can dialog with application RAPPL running on the system DPSZ, it must first establish a connection. The request by LAPPL to connect to RAPPL establishes in the Session Layer, LAPPL as the source and RAPPL as the destination of the connection. The respective Session Controls of DPSA and DPSZ, LSC and RSC, are unique and network-wide to identify the addresses of LAPPL and RAPPL unambiguously.

2-12 47 A4 92UC Rev03 ISO/DSA and ISO Communications

2.4 OSI Addressing Concepts

The network addressing follows the same conceptual principles as addressing a letter or dialling a phone number. In both cases, the targeted destination is accessed only if the addressing is unambiguous. An application, running on the local system, requests the local communication services to establish a connection with a desired correspondent located in a remote system and identified by an address. Each system in a chain of systems through which the connection transits, routes this request by forwarding it to the next system along the chain until the destination is reached. Any configuration error in the sequence may prevent the correspondent from being accessed. The OSI communication architecture being represented by the 7 layers OSI stack in which each layer can be accessed by a specific address, shows that the OSI addressing is conceptually hierarchical.

Service Access Point Within the OSI Reference Model, each layer can be accessed by SAPs:

• for outgoing connections, the (i+1)-entity which implements the layer (i+1) of OSI Reference Model), invokes the services of the (i)-entity by accessing the (i)- SAP that links the two adjacent layers, • for incoming connections, the (i)-entity provides services to an (i+1)-entity by accessing the (i)-SAP that links the two layers.

EXAMPLE: TSAP (Transport SAP) links layer 5 (session) and layer 4 (transport). ❑

Selectors An (i)-Selector identifies a specific (i+1)-entity type, within the set of (i+1)-entities in a given system. Selectors are the addressing information that are exchanged between systems. They are allocated by a system and are unique within the scope of this system.

47 A4 92UC Rev03 2-13 Network Overview and Concepts

2.4.1 General Structure

An (i+1)-entity is uniquely identified in the network by the address of an (i)-SAP. An (i)-SAP is made of an (i)-selector and an (i-1)-SAP.

EXAMPLE: A specific Session-layer is addressed by an address of TSAP, which is composed of a Transport-selector (TSEL) and a Network-SAP (NSAP). ❑

NOTE: Through misuse, the term (i)-SAP is used to mean the address-of-(i)-SAP. An application is identified by its Application Entity Title (A.E.T). It is addressed by an address of PSAP (Presentation Service Access Point) which has the structure shown in Figure 2-7.

PSEL (Presentation selector) PSAP Address SSEL (Session Selector) SSAP Address TSEL (Transport Selector) TSAP Address NSAP (Network Service Access Point) <- addresses in hierarchical order ->

Figure 2-8. OSI PSAP Address Structure

2-14 47 A4 92UC Rev03 ISO/DSA and ISO Communications

2.4.2 Network Layer Addressing: NSAP Address

For further information on the topic treated in this paragraph, refer to the document ISO8348/Addendum 2. For outgoing connections, the local system will use the list of NSAPs to determine the correct Network layer, within the set of these NSAPs. A NSAP address identifies one Network Service Access Point within an End System at which the Network service is available. The NSAP structure as defined in [ISO 8348/Add.2] has the following format:

AFI IDI DSP IDP

Figure 2-9. OSI NSAP Address Structure The IDP (Initial Domain Part) of a NSAP address comprises two parts:

• The AFI (Authority and Format Identifier), which specifies: − the format of the IDI field such as whether or not there are leading zeroes, − the network addressing authority such as ISO or CCITT, responsible for allocating the values of the IDI, − the abstract syntax of the DSP (Domain Specific Part) such as being in binary or decimal. Figure 2-10 summarizes the allocated AFI values by authority and DSP syntax.

47 A4 92UC Rev03 2-15 Network Overview and Concepts

DSP Syntax Authority decimal binary X121 CCITT 36,52 37,53

ISO DCC 38 39

F69 TELEX 40,54 41,55

E163 RTC 42,56 43,57

E164 RNIS 44,58 45,59

ISO ICD 46 47

LOCAL 48 49

Figure 2-10. AFI Values in OSI NSAP Address

• The IDI (Initial Domain Identifier) which specifies: − the network addressing domain from which values of the DSP are allocated − the network authority responsible for allocating values of the DSP for that domain. The DSP (Domain Specific Part) represents a private addressing part and can be encoded in binary or decimal. Its semantics is determined by the authority identified by the IDI. It can contain TRANSPAC or ETHERNET addresses.

2-16 47 A4 92UC Rev03 ISO/DSA and ISO Communications

Figure 2-11 gives the maximum DSP field length by authority and DSP syntax:

DSP Syntax Authority decimal binary X121 CCITT 36,52 37,53

ISO DCC 38 39

F69 TELEX 40,54 41,55

E163 RTC 42,56 43,57

E164 RNIS 44,58 45,59

ISO ICD 46 47

LOCAL 48 49

Figure 2-11. DSP Values in OSI NSAP Address

EXAMPLE (ISO NSAP): The following NSAP 39250F080038543210 can be broken down as follows: 39 250F 080038543210 ------| | | | | | | | ->DSP = 080038543210 | | built from an Ethernet address | | | ->IDI = 250F denotes: | DCC = 250 (for France) | F = right padded mandatory with binary DSP | -> AFI = 39 denotes: Authority: ISO DCC Binary DSP if present DSP maximum length = 14 bytes ❑

47 A4 92UC Rev03 2-17 Network Overview and Concepts

ECMA 117 Recommendation The DSP field is split up into 4 successive fields:

• organization identification which is specified if the authority is DCC or is omitted if not, • subnetwork identification, • address in the subnetwork, • network selector (NSEL). Figure 2-12 gives the maximum length for each field depending on the DSP abstract syntax specified by the AFI:

Organization subnetwork subnetwork type NSEL identifier identifier address

decimal (6 digits ) 5 digits 15 digits 3 digits

binary (2 bytes ) 2 bytes 6 bytes 1 byte

Figure 2-12. Field Lengths in OSI NSAP Address

EXAMPLE (ECMA 117 Recommendation): The ECMA 117 address 3925025643200FE02608C5A2BC01F can be broken down as follows: 39 250 256432 00FE 02608C5A2BC0 1F ------| | | | | | | | | | | | | | | | | -->selector 1F | | | | | | | | | -->address in the subnetwork | | | | = MAC address | | | | | | | -->subnetwork identification: | | | LAN identification | | | | | ->organization identifier = 256432 (Bull) | | | ->IDI = 250 (France) | -> AFI = 39 (ISO DCC) ❑

2-18 47 A4 92UC Rev03 ISO/DSA and ISO Communications

A network entity may need to support more than one NSAP because of the following: 1. The system may support one NSAP address for each directly connected subnetwork. 2. Some applications, with no T-selector or S-selector are addressed directly by the NSAP, each needing a specific NSAP. 3. Several authorities may administer the site and so allocate different NSAP formats.

Special NSAP Format for RFC1006 A special NSAP address format has been defined for use when OSI applications are run over networks that do not provide the OSI Network service. This format covers TCP/IP networks supporting COTS using RFC1006. The Telex AFI with DSP decimal encoding is used. The Telex number in the IDI plus the Prefix field of the DSP identify a particular network. The remainder of the DSP encodes network specific information. The IDI value is: 00728722 (University College London Telex Number) The Prefix value is: 03 The remainder of the DSP field contains:

• the Internet address expresssed as 12 mandatory decimal digits (for example, 129182000020). • the RFC1006 port number expressed as 5 optional decimal digits (for example, 00102, the default value). • one digit of padding (set to 0).

47 A4 92UC Rev03 2-19 Network Overview and Concepts

Figure 2-13 gives an example of the special NSAP format for an application whose Internet address is 129.183.1.84 listening on port 102.

54 00 72 87 22 DSP

prefix IP address port padding

03 12 91 83 00 10 84 00 10 2 0

Byte 1 2-5 6 7-12 13-15 16

optional

Figure 2-13. Example of RFC1006 NSAP Address Format

2.4.3 Transport Layer Addressing: TSAP Address

A TSEL (Transport Selector) like other selectors, is significant within the scope of the End System to which it is allocated. A transport selector is used to identify one and only one session entity within the End System. The term Session Entity implies not only the OSI communications layer which implements the OSI session protocol but also applications directly using a Transport Programmatic Interface. Transport Selectors are allocated independently for each End System since no global authority is required for this allocation. Transport Selector values are directly encoded as TSAP-id parameters of Transport Connection Request and Confirm Data Units. The TSEL, suffixed by the NSAP address, becomes an address of TSAP. Both TSEL and NSAP are used by the Front-End processor to choose the host for an incoming connection using a UT (User of Transport) object.

2-20 47 A4 92UC Rev03 ISO/DSA and ISO Communications

2.4.4 Session Layer Addressing: SSAP Address

A session selector is used to identify one Presentation entity. Session selectors are to be directly encoded as SSAP-id parameters of the Connect and Accept Session Protocol Data Units.

2.4.5 Presentation Layer Addressing: PSAP Address

A Presentation selector is used to identify one Application Entity. Presentation selectors are to be directly encoded as PSAP-id parameters of the Connect and Accept Presentation Protocol Data Units.

2.4.6 Application Layer Addressing: AET

An application is identified by its AET (Application Entity Title). Presently OSI applications must provide both local and remote PSAP to OSI layers:

• Remote PSAP to identify its correspondent, • Local PSAP to identify itself. In later releases, directory services will help applications get the PSAP address corresponding to a given AET.

47 A4 92UC Rev03 2-21 Network Overview and Concepts

2.4.7 Default Local Addresses

When calling communications services, the local application must supply both local and remote PSAPs to identify itself and its remote correspondent. Both local TSEL and local NSAP are optional. If the local TSEL is absent, it is set by the session layer to the default local TSEL implicitly configured. The local NSAP is set by the Frontend processor, depending on the network attachment chosen. If an application does give a local NSAP, it is considered a reconnection, and the Frontend processor will then use the local network attachment which correspond to this NSAP provided. Only for local connections where the two applications are located in the same host, the session layer recognizes some configured local NSAPs, allowing looping in the host itself but not in the Frontend processor. In the case where the DPS 7000 connects directly to another DPS 7000 over the ISL, the first NSAP defined for the LSYS is taken into account.

2-22 47 A4 92UC Rev03 ISO/DSA and ISO Communications

2.5 OPEN LAN ACCESS: ISO/DSA PLUG

2.5.1 ISO - DSA Plug Functions

In order for DSA applications such as IOF, TDS and UFT to work with the ISO stack and to benefit from all ISO sublayer services, a mechanism has been implemented in GCOS 7. This mechanism is an on-line and transparent module which converts the DSA session to an ISO session by migrating from DSA addressing to OSI addressing. These PID (Prise ISO-DSA, French for ISO-DSA Plug) modules are invoked depending on the information given on addressing and configuration:

• at connection time, • and when needed during data transfers.

Migration Goals The Bull DSA proprietary communication architecture is not so far removed from OSI communications architecture. However, DSA addressing which involves session address and application mailbox, differs considerably from OSI hierarchical addressing. To be compatible, migration is necessary from non-hierarchical (flat) DSA addressing to OSI addressing. Addressing migration is performed by the PIDa, the addressing PID which is the module interfacing the session with the transport layer at each inward or outward connection requests. The advantages of such a mechanism are:

• Any site having a mix of OSI applications such as X400 and FTAM, and DSA applications will use only one communications stack and one network configuration to communicate between both sets of environments. Without such a mechanism, two completely separate network architectures have to coexist, thereby increasing the overheads of communications management with the increase in the development and use of OSI applications.

47 A4 92UC Rev03 2-23 Network Overview and Concepts

• Foreign systems can connect to Bull proprietary applications whose layers 1 through 5 fully conform with the OSI stack. This means that such systems do not have to undergo regeneration and reconfiguration to comply with Bull networking standards. • Connections between GCOS 7 and DIWS (DSA-ISO Workstation) over the ISL are direct. The function of the PID in the DPS 7000 can be shown as follows:

other ISO application application DSA application

other ISO DSA session session session or GXTI PID

iso addressing dsa address dsa address and iso protocol iso protocol dsa protocol

Figure 2-14. ISO-DSA Plug (PID) Functions

2.5.2 Protocol Conversion Mechanism

The PIDp (protocol-PID) module performs in a transparent way, the conversion from DSA session protocol, used by DSA applications on the DPS 7000, to ISO session protocol. This protocol conversion follows Bull SID (specifications ISO-DSA) standards which allow direct connection to and from already existing applications on ISO- DSA stations to use their native ISO session and without the relay of a gateway. It also supports DPS 7000 to DPS 7000 connections on an ISO network (double conversion). When activated for a given session connection, this module transforms incoming ISO SPDU (Session Protocol Data Units), into DSA letters before handing them over to VCAM. Similarly, outgoing DSA letters are transformed into ISO SPDUs.

2-24 47 A4 92UC Rev03 ISO/DSA and ISO Communications

2.5.3 Address Conversion Mechanism

• For both Local (L) and Remote (R) systems involved in the connection, the address conversion performed by the PIDa consists of: LMBX [EXT], LSCname <- translated into -> LSSEL, LTSAP RMBX [EXT], RSCname <- translated into -> RSSEL, RTSAP

where MBX is the mailbox and EXT the mailbox extension. • The ISO addressing terms for a DSA application are formed as follows: SSEL = "blank character" + MBX + EXT

For the conversion, the ISO and/or DSA addresses of the 2 connected end- systems are taken by the PIDa from the basic network or directory configurations. TSAP = TSEL + NSAP list

• TSEL is used to select a session layer service among those provided by the DPS 7000: − ISO session, − PID + DSA session. − GXTI. ISO session and GXTI can be accessed by one or several TSELs. • To access the PID, one PID-TSEL is always needed for each system. When not explicitly declared in the network configuration, the default PID-TSEL internally supplied is: "PID_SELECT" in ASCII coding: "5049445F53454C454354"X

47 A4 92UC Rev03 2-25 Network Overview and Concepts

other ISO DSA applications applications applications or ISO DSA other session session session

PID

TSELx TSELy TSELz PID_TSEL

Figure 2-15. Examples of TSELs in the DPS 7000

• Two systems may have the same TSEL where, for example, both have the PID_TSEL default value. The NSAP is used to select the FEP which accesses the TSEL. Each NSAP must be unique in the network configuration. For further details on OSI addressing, see Paragraph 2.4. If the FEP gives access to 2 different systems which have the same TSEL, there must be at least 2 different NSAPs to select the host:

HOST 1 HOST 2

PID TSEL PID TSEL value default value default

FRONTEND

NSAP1 NSAP2

Figure 2-16. Two Systems with the Same TSEL

2-26 47 A4 92UC Rev03 ISO/DSA and ISO Communications

HOST 1 HOST 2

PID TSEL PID TSEL value 1 value 2

FRONT END

NSAP

Figure 2-17. Two Systems with Different TSELs

2.5.4 Examples of Network Configurations

Example with protocol conversion between a DPS 7000 and a DSA/ISO Workstation on the ISL:

DPS 7000 DSA/ISO Workstation

S7-1 X1

ISL

Figure 2-18. PIDp Generation Example The source generation to perform the network configuration of the DPS 7000 S7_1 is: SYS S7_1 PF=LSYS SCID=24:25 ISL=(51-23-45 EA01); SYS X1 PF=STID PID=SID ISL=53-23-45;

The parameter PID=SID allows to use the protocol conversion by the PIDp module. The DSA address is determined from SCID. For more details on network configuration, see the manual Network Generation.

47 A4 92UC Rev03 2-27 Network Overview and Concepts

Below is an example with protocol and address conversion:

S7-1 X1 NSAP=04 NSAP=01 PID=0102

DN1 X2 NSAP=02 NSAP=05

NSAP=06 X3 DN2 I NSAP=03 S L S7-2 PID=0203

Figure 2-19. PIDa Generation Example The source generation to perform the network configuration of S7_1 of ISO address is: SYS S7_1 PF=LSYS NSAP=04 PID=0102 SCID=24:25 ISL=(51-23-45 EA01); SYS DN1 PF=DN7100 NSAP=05 PID=ISO PSI=CC01; SYS X1 PF=STID NSAP=01 PID=ISO ISL=52-23-45; SYS X2 PF=STID NSAP=02 PID=ISO ISL=53-23-45; SYS X3 PF=STID NSAP=03 PID=ISO ISL=54-23-45; SYS DN2 PF=DN7100 NSAP=06; SYS S7_2 PF=DPS7 PID=0203;

The ISO address is determined from NSAP and PID. The parameter PID=ISO retrieves the PID TSEL with its default value PID_SELECT. The DSA address is determined from SCID. These parameters, explicitly declared or configured by default, will be dynamically retrieved by the communications routing services, namely the PIDa module. For more details on network configuration, see the manual Network Generation.

2-28 47 A4 92UC Rev03 ISO/DSA and ISO Communications

2.6 Use of TNS Extension for ISO Sessions

For an outgoing ISO connection from the DPS 7000 host to a remote system through the FEP, the full ISO address (TSEL + NSAP list) must be sent to the FEP. The FEP connected to the ISL can be either the CNP7 or the Datanet. The FEP then chooses one NSAP among several, depending on the network used to access the remote system. The calling TSAP, the called TSAP and the Quality-of-Service parameters are exchanged between TNS and the FEP software in an extension of the CR TPDU of transport protocol. The connection between TNS and the FEP is seen as a channel connection providing the session-to-transport interface from the host to the FEP. This transport protocol extension is declared at NETGEN by the ISO:2 parameter of the RTS directive.

2.7 Use of FEPS for ISO sessions

FEPS supports both DSA and ISO sessions in native mode without any restrictions.

2.8 Use of OCS for ISO sessions

OCS supports both DSA and ISO sessions in native mode without any restrictions.

47 A4 92UC Rev03 2-29 Network Overview and Concepts

2.9 Connection Mechanism

2.9.1 ISO/DSA Session Connection Mechanism

2.9.1.1 Introduction

ISO/DSA connections are established on GCOS 7 by VCAM-DSA. VCAM uses the Session Routing module to select a Session Route. When necessary, the OPEN LAN ACCESS module (PIDp or PIDa) is called in order to translate DSA to ISO protocol or address. A Session Route gives the path to be used for outward session connections. A Session Route is implicitly defined when describing the remote system and its associated servers. A Session Route can be explicitly defined at Network Generation to manage its state (LOCK or not) and when quotas are to be used. Two types of Session Routes are available:

• Session Route through server (FEPS, OCS, via TNS) For TNS there is a Session Route per RTS but no TNS specific Session Route. • Session Route through remote transport station (RTS) when the connections are established via TNS.

2.9.1.2 Outward Connection Mechanism

Without Quotas (default value of quota=1) An algorithm (function of the RSC address) is used to balance the outward connections over all the available routes. This load balancing takes in account the number of outward and inward connections already established through the session route.

2-30 47 A4 92UC Rev03 ISO/DSA and ISO Communications

With Quotas Defined The session routing function will try to balance, for a given remote system, the outward connections depending on the quotas defined for the routes to this remote system and depending on the connection already established. If one or several session route are defined with quota equal to zero, they will be considered as backup routes.

Notes: The algorithm function of the RSC address is always used when the routes are of the same "weight" (either all quotas are one, or quotas are different from zero). When a connection attempt fails, the session routing function automatically retries towards another route in a way which is transparent for the application. When a connection request via a session route is rejected, this route will be reused only if all other routes are unavailable or if new inwards connections have been established by this route.

Choice of an Outgoing Transport Station

• outward connections through OCS: OCS Front End chooses a transport station to reach the remote system. If the remote system can be reached via several RTS’s (Remote Transport Stations). OCS Front End chooses the first RTS in the list. The other RTS’s will be used as backup. • outward connections through FEPS/Datanet: The Datanet front-end chooses the transport station to reach the remote system. DNS takes the first TS in its list, the other TSs are used as backup. • outward connections through TNS: As for the routes via servers, it is possible to define quotas on the routes via RTS or to use default quotas (quota=1). TNS will try to balance the connections over all the available RTSs depending on the inward connections already established and on the value of quotas.

47 A4 92UC Rev03 2-31 Network Overview and Concepts

2.9.1.3 Inward Connection Mechanism

Inward connections from a remote system are accepted by VCAM only if the entering server is defined in the list of servers for this system. When connections enter via TNS, the connection is accepted only if the entering RTS is defined in the list of RTS of this system. When necessary, the OPEN LAN ACCESS module (PIDp or PIDa) is called in order to translate ISO to DSA (protocol or address).

2.9.2 ISO Session Connection Mechanism

2.9.2.1 Introduction

A session connection is established between a local TSAP and a remote TSAP. In order to establish an outward connection, a session routing function is invoked by the session layer. This session routing module is in charge of choosing a transport layer server, either TNS, OCS or an FEPS occurrence, with the appropriate FEP (frontend processor). The choice is made using the given remote TSAP address and the information in the basic network and directory configuration if it exists.

2.9.2.2 Outward Connection Mechanism

Session Routing Service In the DPS 7000, the following events occur:

• VCAM invokes the session routing service for selecting a server, • the session routing service chooses a server by checking the first NSAP address given in the destination address, and returns the server reference to VCAM, • when a connection request towards either TNS, OCS or an FEPS occurrence fails, VCAM calls on the session routing service to find another available server; this process continues until a new server is found and VCAM retries the connection request towards this new server,

2-32 47 A4 92UC Rev03 ISO/DSA and ISO Communications

• when all attempts using the first NSAP fails, the next NSAP in succession is used, • an internal mechanism is implemented to avoid infinite looping during these retries, • if no route is available to establish an outward connection towards any of the FEPs, using all the NSAPs in the list, the connection will fail.

NOTE: Although each destination NSAP is tried separately by the session routing service, the full list of NSAPs is always supplied to the transport layer at each call from VCAM.

Subdomains The list of available servers and passthroughs or neighbors to use is defined by the information in the basic network and directory configuration:

• if no subdomain is declared in the directory configuration, all the started servers and available FEPs are used, • if subdomain objects are declared, valid servers are restricted to those able to access the passthroughs or neighbors declared in the SUBDOMAIN directives, • choosing a subdomain from a given NSAP uses a best-matching algorithm between this NSAP and all the declared NSAP prefixes; each prefix identifies a subdomain and the largest size which matches, is the best match which selects the subdomain. The SUBDOMAIN directive is mandatory in accessing a system directly connected to the Local Area Network, without intermediate FEP, such as another DPS 7000. It makes the link between a NSAP address (known to the ISO application) and the physical address of the system on ISL (described in the basic network configuration and known to TNS).

47 A4 92UC Rev03 2-33 Network Overview and Concepts

Quality of Service The ISO outward connection route, when present, may be chosen by matching:

• the desired and the minimum QOS (Quality Of Service) requested by the application in the QOS parameters, • with the offered quality of service configured in the generation by means of the SUBDOMAIN object. The requested desired and minimum class are taken into account as follows:

Quality of Requested Quality of Service Service Offered (desired and minimum)

case 1 case 2 case 3 case 4

Q minimum Q desired Maximum

Q minimum Q desired Minimum Q desired

result of refusedaccepted accepted refused connection 2nd choice request (Q minimum)

Figure 2-20. ISO Quality of Service Output network ways may be divided into classes which can be dispatched over the possible passthroughs. Examples of criteria affecting classes are:

• communication costs, • level of throughput, • and types of subnetwork.

2-34 47 A4 92UC Rev03 ISO/DSA and ISO Communications

2.9.2.3 Inward Connection Mechanism

The ISO session layer is warned of an incoming connection request by the arrival of a CONNECT SPDU from the transport layer. The called address is then computed by the session layer to identify a VCAM-ISO SSAP which allows connection to the application as the endpoint of the connection. For selecting the ISO-SSAP, the ISO session layer scans the SSAPs supplied by the local ISO applications, firstly SSAPs with explicit NSAPs, then those without:

• if no ISO-SSAP is selected, the connection is rejected, • if an ISO-SSAP is selected, the ISO session layer notifies the application concerned.

2.9.3 FEPS Pseudo-Transport

2.9.3.1 Inward Connections

ISO transport functions are fully supported by the Datanet which provides the actual transport connection, whereas the DPS 7000 only has the visibility of a pseudo-transport, namely:

• on the DPS 7000 side, the FEPS occurrence manages the communications controller which links the Datanet by its PSI channel, • on the Datanet side, DNS establishes the transport connection between its local transport layer and the remote transport. The management of the exchange interface by FEPS and DNS follows a symmetrical pseudo-transport protocol, which is only in charge of ensuring the transport-session interface between the DPS 7000 and the Datanet. Since the data transfer over the PSI is highly reliable, pseudo-transport protocol is only concerned with:

• connection and disconnection requests, • acknowledgement, • full duplex data transfer.

47 A4 92UC Rev03 2-35 Network Overview and Concepts

When FEPS receives a transport connection request from VCAM, it receives the calling and called TSAP and QOS, the called TSAP possibly being provided with several NSAPs. All these parameters are sent to DNS which establishes an end-to-end transport connection towards the ISO network, using TSAPs and ISO routing services. For further details, refer to DNS-V4 documentation.

2.9.3.2 Outward Connections

Transport Connection via Datanet When the Datanet receives a transport connection, it analyzes the called TSAP. If it matches its internal description of the host mainframe, a pseudo-transport connection with addressing and QOS information is sent to FEPS. See AL object in the DNS-V4 documentation.

Pseudo-Transport and Upper Layer Selection When FEPS receives an inward connection request, it operates like TNS in retrieving the upper layer. The software module used is the same in both connection cases.

2-36 47 A4 92UC Rev03 ISO/DSA and ISO Communications

2.9.4 TNS Connections

2.9.4.1 Outward Connections

Transport Layer TNS acts as a full transport layer on ISL network by using network information located in the basic network description, namely, ETHERNET addresses. When VCAM sends a connection request to TNS, it supplies TNS: • TSAP addresses (calling and called), • connection parameters, • the passthrough to use, the passthrough being found by the session routing service. TNS then attempts a transport connection towards this passthrough, using all its configured information: • its physical address, • specific parameter values for transport, • its own list of passthroughs which TNS uses for its own transport routing.

Network Layer Since this layer is empty, the only routing function supported is one which involves searching the configuration tables for a valid network route to access the remote transport layer. In connectionless mode, a valid network route is one which is eligible to proceed from an enabled LPL (Local Physical Link) to a RPL (Remote Physical Link) whose state is not known. The DPS 7000 operates in connectionless mode as follows: • the TPDU comprising the connection request and subsequent TPDUs are directly sent over the network • if the RPL does not acknowledge the request, it is assumed that either the network required cannot be used or the RPL cannot be accessed • the transport service then sends a retry request. This procedure is repeated until the transport request is finally acknowledged or the number of retries over all the configured networks, is exhausted.

47 A4 92UC Rev03 2-37 Network Overview and Concepts

Frame Transmission When several ISL network attachments are simultaneously available, TNS chooses the one with the lowest activity and is able to switch to another network as soon as the current chosen one fails. A frame is set up with the physical ETHERNET address parameters of both the local and remote systems and the LSAP binary values of 20 (ISO LSAP). Once set up, the frame is conveyed in a channel program which transmits it to the local network board to be send over the ISL cable. The addressed remote entity will then receive the frame.

2.9.4.2 Inward Connections

Frame Reception The ISL controller, when enabled, listens permanently to the cable. A first level of filter is performed by this controller according to the destination ETHERNET address of the frame. If it matches either its own address or any of its configured multicast addresses, the frame is taken.

Dispatching from Link Layer to Upper Layers When the source address belongs to the known interval of source addresses (by default: from 080038100000 through 0800387FFFFF), the frame is dispatched by the controller over each configured logical I/O link called the LT (Logical Terminator) supporting the destination LSAP. LTs are chosen according to their configured type and address, as follows:

• one or more LTs (2 by default) to receive frames with LSAP=ISO, • one or more LTs (2 by default) to receive frames with LSAP=TCPIP, • only one LT to receive frames with LSAP=RM (Remote Maintenance). If no LT supports the destination LSAP, the frame is considered "foreign":

• valid foreign frames are appropriately dispatched over foreign LTs which are internally configured by GCOS 7 and need not be declared by the user, • if no foreign LT is configured, foreign frames are discarded. All frames in error are discarded.

2-38 47 A4 92UC Rev03 ISO/DSA and ISO Communications

The first level of dispatching being passed, the frame is then transmitted by the LCT (Local Controller) to TNS on a given LT:

• if the LT is specified with LSAP=RM, the frame is processed by the remote administration module of TNS, • if the LT is specified with LSAP=ISO, the frame is dispatched to the network layer, • if the LT is specified with LSAP=TCPIP, the frame is dispatched to TCPIP module.

Network Layer The received frame is analyzed according to its network header. If its header is ISO8473 null subset (standard network protocol), the source ETHERNET address is checked among all those configured for identifying the sender:

• if the configured address is found, the TPDU is extracted and sent to the transport layer, • otherwise the frame is discarded.

Transport Layer On receiving the TPDU from the network layer, the transport layer processes it according to its characteristics:

• if it is a connect request, the destination TSAP is used to select the upper layer, • if it is not a connect request, its connection identifier allows the transport layer to process it for an already existing connection.

NOTE: From GCOS 7-V7 onwards, full ISO addressing and protocol capabilities are supported by ISO Level 2 transport protocol (ISO:2) on the condition that the DPS 7000 is front-ended by a CNP7 running on version => A2 or a Datanet running on version => V4.0.

47 A4 92UC Rev03 2-39 Network Overview and Concepts

Selecting the Upper Layer Selecting the upper layer depends on the TSEL. Each entity of the upper layer is called to check which one owns the given TSEL. The addressing PID module, as in outward connection mechanism, is also called upon to assume compatibility with DSA-session connections, and address conversion from ISO to DSA.

2.9.5 OCS Connections

2.9.5.1 Outward Connections

Transport Layer OCS Front End acts as a full ISO transport layer by using network information located in the OCS Front End configuration description. When OCS Front End receives a transport connection request from VCAM it receives:

• TSAP addresses (calling and called), • connection parameters, From its configuration description it searches the passthrough system to use and attempts a transport connection towards this passthrough, using all its configured information:

• its physical address, • specific parameter values for transport,

Network Layer From the NSAPs, this layer determines the access paths to remote systems for the ISO and IPS stacks.

Frame Transmission

The LLC layer transmits the PDU to the Adapter, which inserts the local MAC address, and then emits the frame in the format fitting the network.

2-40 47 A4 92UC Rev03 ISO/DSA and ISO Communications

2.9.5.2 Inward Connections

Frame Reception

Once the OCS server has started, the OCS Front End (with its associated Adapter card) “ listens ” the network. The destination address of the entering frame allows a first level of filtering. The following addresses are accepted:

• Local MAC address of the Adapter card • Broadcast address (all bits set to 1) • Multicast address (ISO)

Dispatching from Link Layer to Upper Layers The LLC layer uses the LSAP field of the frame to determine the destination stack (ISO, DIWS, or IPS). If the LSAP is invalid, the frame is discarded.

Network Layer This layer verifies that the local NSAP is valid for the OCS Front End. If the NSAP is not valid, the frame is discarded.

Transport Layer On receiving the TPDU from the network layer, the transport layer processes it according to its characteristics:

47 A4 92UC Rev03 2-41 Network Overview and Concepts

2.10 Direct Interfaces to Communication Layer

2.10.1 Transport Interface

The GXTI module implements a fully compatible interface with X/OPEN XTI specifications for both ISO and TCP/IP transport providers.

2.10.2 Session Interface

An ISO session interface service is available in VCAM, offering full ISO V1 and V2 session services as described in ISO standards.

2-42 47 A4 92UC Rev03 3. TCP/IP Communications

TCP/IP (Transmission Control Protocol/Internet Protocol) is a layered set of protocols. It is also known as IPS (Internet Protocol Suite). TCP/IP is widely used in the UNIX world.

3.1 TCP/IP Layered Architecture

Figure 3-1 shows the layered architecture of TCP/IP.

SMTP FTP Telnet XTI NFS SNMP Application

Presentation

Session

TCPICMP UDP Transport

IP Network

Link Link

Physical Physical

X25 Ethernet Token FDDI Network Ring

Figure 3-1. TCP/IP Layered Architecture

47 A4 92UC Rev03 3-1 Network Overview and Concepts

In Figure 3-1 TCP/IP is presented as in 7 layers (like the OSI model). However, in contrast with the ISO-DSA and ISO architectures discussed earlier in this manual, in TCP/IP the presentation and session layers are not really used.

Application Layer SMTP (Simple Mail Transfer Protocol) is a mail/messaging facility. FTP (File Transfer Protocol) is a "de facto" TCP/IP standard for file transfers. NFS (Network File System) is a distributed file access facility. It supports client/server architecture. An NFS client accesses files, an NFS server provides files for access.

RPC (Remote Procedure Call) part of NFS allows to call remote procedures as if they were local. Telnet (TErminaL NETwork) enables terminals to access remote systems. SNMP (Simple Network Management Protocol) is a network administration facility. XTI (X/Open Transport Interface) provides a direct interface to TCP or UDP.

Presentation Layer The presentation layer is not used in TCP/IP.

Session Layer The session layer is not used in TCP/IP.

Transport Layer TCP and UDP are equivalent to the OSI transport layer. TCP is a connection-oriented transport mode. TCP negotiates the maximum datagram size, breaks up messages into datagrams (for sending), re-assembles datagrams into messages (after receiving), re-transmitting "lost" datagrams, and re- sequencing datagrams (which arrive in the wrong order). It is suitable where a reliable communication of messages is needed. UDP is a connectionless transport mode. It is used for messages which fit into a single datagram and which can be re-sent if not acknowledged. It does not guarantee the order of arrival. It does not guarantee arrival at all. ICMP is a administrative protocol. It managers PING messages.

3-2 47 A4 92UC Rev03 TCP/IP Communications

Network Layer IP (Internet Protocol) is equivalent to the OSI network layer. IP receives datagrams from TCP, ICMP and UDP. Each datagram has a specified destination. IP is responsible for routing individual datagrams, and consequently it must know the network configuration. IP does not know how datagrams relate to one another and is not concerned with the structure of the message (if this is larger than 1 datagram). IP keeps track of all the routes and handles incompatibilities between different transport media. If IP cannot deliver a datagram within a reasonable time ("time to live"), it discards the datagram. If TCP is used at the transport layer, then TCP must arrange for the re-transmission of "lost" datagrams. If UDP is used at the transport layer, then the application must arrange for the re-transmission of "lost" datagrams.

Data Link Layer This is equivalent to the OSI data link layer. TCP/IP offers LAPB (Link Access Procedure, Balanced) for synchronous connection to X25. TCP/IP offers LLC1 (Logical Link Control 1) and MAC (Media Access Control) for LAN connections.

Physical Layer This is equivalent to the OSI physical layer. TCP/IP offers switched circuits for X25. TCP/IP offers CSMA/CD (Carrier Sense Multiple Access with Collision Detection), Token Bus, Token Ring, and FDDI (Fiber Distributed Data Interface) for LANs.

47 A4 92UC Rev03 3-3 Network Overview and Concepts

3.2 TCP/IP Addressing Concepts

3.2.1 IP Addresses

Figure 3-2 shows the format of IP addresses.

7 bits 24 bits

0Network Local Class A

14 bits 16 bits

1 0 Network Local Class B

21 bits 8 bits

110NetworkLocalClass C

Figure 3-2. IP Address Format IP addresses are of fixed length. The length is 4 bytes (32 bits). Each IP address is made up of two parts: 1. Network Number. This is the first (leftmost) part of the address. 2. Local Address. This is the "rest" of the address.

3-4 47 A4 92UC Rev03 TCP/IP Communications

The division between "network" and "local" depends on the class of the address. There are 3 classes: A, B, and C. Class A The high order bit is 0 (which defines this address to be class A). The next 7 bits are the network number. The last 24 bits are the local address. Class is used if there are few networks and many hosts (on the networks). Class B The high order bits are 10 (which defines this address to be class B). The next 14 bits are the network number. The last 16 bits are the local address. Class is used if there are many networks and many hosts (on the networks). Class C The high order bits are 110 (which defines this address to be class C). The next 21 bits are the network number. The last 8 bits are the local address. Class is used if there are many networks and few hosts (on the networks). IP addresses are usually shown in "dot notation". In dot notation, the IP address is shown as a string of up to 4 decimal numbers. Each decimal number must be less than or equal to 255. A dot (.) is used to separate the decimal numbers. Each decimal number is interpreted as a 1 byte hexadecimal number. Each byte is assigned to the IP address (in the format shown in Figure 3-2) from left to right. If fewer than 4 bytes are present, the remaining bytes of the IP address are set to zero. Blanks are not allowed in an IP address. The following IP addresses are reserved: 0.0.0.0 Own address at booting. 127.0.0.1 Loopback address. 255.255.255.255 Limited Broadcast.

47 A4 92UC Rev03 3-5 Network Overview and Concepts

3.2.2 MAC Addresses

A MAC address is a string of 12 hexadecimal digits arranged in pairs. The pairs are separated from each other by a colon (:) character. Blanks are not allowed in a MAC address. The following are examples of MAC addresses: 08:00:38:00:00:01 08:00:38:00:00:02 The ARP table associates a MAC address with its corresponding IP address. The ARP protocol can automatically load this table. In the case of OCS Front End, for a remote TCP/IP station, the association between its IP address and its MAC address can be done using ARP commands in the IPS configuration (see the manual Network Generation).

3-6 47 A4 92UC Rev03 TCP/IP Communications

3.3 TCP/IP Implementations on GCOS 7

3.3.1 TCP/IP via FCP7

Figure 3-3 shows the access to TCP/IP via FCP7.

GCOS 7

Applications

GXTI

OCS

TCPICMP UDP TCPICMP UDP TCPICMP UDP TCPICMP UDP IP IP IP IP Layers 1/2 Layers 1/2 Layers 1/2 Layers 1/2 FCP7 FCP7 FCP7 FCP7

FDDI FDDI FDDI FDDI

Figure 3-3. TCP/IP via FCP7 A DPS 7000 can be connected to FDDI networks. Up to 4 FCP7 integrated controllers can be installed, and each FCP7 can be connected to a different FDDI network (as shown in the figure). In the GCOS 7 NETGEN, each FCP7 must be declared via an LCT directive, and each OCS server occurrence via an SVR directive. An LT is implicitly generated for IPS in each FCP7.

47 A4 92UC Rev03 3-7 Network Overview and Concepts

If more than 1 FCP7 is configured to run IPS (IP Suite), then OCS performs multi- stacking management. This is known as "Multi-IPS". In the text below, an FCP7 configured for IPS is referred to as an "IPS FCP7".

NOTE: This TCP/IP transport can also be used to carry RFC1006 TPDUs (See paragraph 1.8).

Multi-IPS The Multi-IPS configuration is done statically by the "addition" of each local IPS stack configuration. The user configures each of the IPS FCP7s. OCS automatically "adds" the individual configurations to produce the Multi-IPS configuration. If an IPS FCP7 configuration is subsequently modified, OCS automatically applies the modifications to the Multi-IPS configuration. At Application level, Multi-IPS gives the same visibility (as far as is possible) as a Multi-Homing site. Note that "at Application level" means that OCS is not a re- router. Multi-IPS applies the RFC1122 recommendations. Its application choices are:

• "ANY" means "ALL". A bind without a local address is proposed to each IPS FCP7. In this context, bind means the association of a local address with the transport end-point. • A previous "ANY" bind is automatically applied to each IPS FCP7 which starts subsequently if its port number is free. If the port number is not free, the bind is not applied. • A new incoming UDP dialog is responded to by the "incoming" IPS FCP7 (that is, the one which received the request). • For a new outward UDP dialog or TCP connection, the IPS FCP7 chosen is the one which has the most precise description of the IP address (or mask) of the remote site (or network) in its IPS stack configuration. • If an attempt to make a TCP connection fails (that is, a failure at connection time), then Multi-IPS automatically retries on another IPS FCP7 (as in the case of DSA). This particular feature is better than that it is required in RFC1122. • If an established TCP connection fails (that is, a failure after connection time), then the application must re-start the connection (Multi-IPS does not do this).

3-8 47 A4 92UC Rev03 TCP/IP Communications

3.3.2 TCP/IP via OPEN7

Figure 3-4 shows the access to TCP/IP via OPEN7.

GCOS 7

Applications

Files TDS IOF ORACLE GXTI

XTI daemon

SQL*Net NFS FTP Telnet Affinity XFORMS Relay

TCP

IP FDDI Driver ISL Driver

FCP7 ISL Controller

Layers 1/2 Ethernet ISL

FDDI

Figure 3-4. TCP/IP Access via OPEN7

47 A4 92UC Rev03 3-9 Network Overview and Concepts

TCP/IP which is implemented by OPEN7 is available to the DPS 7000 system:

• either through the ISL • through the FCP7 • or through the X25 connection giving access to an X25 network (WAN). In the case of the X25 connection, the AX25 gateway executing in the Datanet or the CNP7 (CNS A2) provides the interface between either FEPS (Datanet) or TNS (CNP7) and a specific driver for TCP/IP LTs.

Link Layer Access in TNS The TCP/IP implementation in OPEN7 needs an access to the ISL link. The ISL controller is shared by TNS and an OPEN7 specific driver for TCP/IP. The controller is still administratively managed by TNS, but the OPEN7 specific TCP/IP driver manages a part of the logical I/O links called Logical Terminators (LTs).

Link Layer Access in FCP7 The TCP/IP implementation in OPEN7 needs an access to the FDDI link. The FCP7 is shared by OCS and an OPEN7 specific driver for TCP/IP. The FCP7 is still managed administratively by OCS, but the OPEN7 FDDI driver accesses layers 1/2 of the FCP7 directly via an implicitly generated LT (Logical Terminator). The OPEN7 FDDI driver directly accesses layers 1/2 of the FCP7 via an implicitly generated Logical Terminator (LT). For IPS frames, a second level of filtering is done on the IP address. If the IP address corresponds to that of OPEN7, the frame is transmitted to OPEN7. All other frames are transmitted to the IPS stack of the FCP7.

3-10 47 A4 92UC Rev03 TCP/IP Communications

3.3.3 TCP/IP via INTEROP7

INTEROP7 is available to the DPS 7000 and DPS 7000/XTA systems.

In the case of a DPS 7000/XTA, TCP/IP communications can be performed thru the commodity TCP/IP software associated with this Decor. Then access are made directly from GCOS7 thru basic services allowing to communicate with the TCP/IP modules. Services are provided also at the level of the Extended Virtual Machine, or at the level of the commodity code itself to use TCP/IP protocols for access to applications or data bases from the Open world. GCOS7 services or applications can communicate thru TCP/IP, using Socket services (SOCKG7) or RPC services (themselves built on SOCKG7). For example: • TDS TCP/IP access TCP/IP stack thru SOCKG7 • FTP, GCOS7 providing access to its File Systems

DPS 7000 Open world services include services such as: • FTP7 for the support of FTP File Transfer • OpenGTW (OpenGTWriter) for the support of remote printing • OP7GW (Open7 Gateway) for SQL*Net, ESP7 and Natstar access.

DPS 7000 services directly performed on the commodity software include for example: • Oracle with SQL*Net use on the network • Java, with Corba use on the network See Figure 3-5, TCP/IP via INTEROP7 for DPS 7000/XTA .

47 A4 92UC Rev03 3-11 Network Overview and Concepts

DPS 7000/XTA

GCOS 7 GCOS 7 Applications and Services using TCP/IP telecommunications

RPC

SOCKG7

Extended virtual machine

Open world services

WINSOCK Commodity Commodity services software TCP/IP + Driver

n LAN Adapters

Figure 3-5. TCP/IP via INTEROP7 for DPS 7000/XTA

3-12 47 A4 92UC Rev03 4. GCOS 7 View of the Network

4.1 Describing the Network

The first step before using GCOS 7 communications is to configure the network. An individual network generation is performed for every participating system of the network, each with its own generation description to describe its own local view of the network.

The most basic network is made out of a DPS 7000 and its direct connections to a LAN (Local Area Network), the next level is made out of a DPS 7000 and its FEP (Front End Processors). More complex configurations may include several host systems interconnected thru LAN’s and WAN’s (public Wide Area Networks for example)

GCOS7 network generation tool is NETGEN.

OCS Front ends do not need a generation step, but are configured thru configuration files loaded when the corresponding OCS server is started (thru the STSVR command).

MainWay, CNP7 and Datanet have their own generations (see corresponding manuals).

This section describes NETGEN and OCS configurations.

47 A4 92UC Rev03 4-1 Network Overview and Concepts

4.2 NETGEN Utility

4.2.1 Network Description

A NETGEN network description may comprise the following:

Basic Network Description This part describes the local DPS 7000 for which the local view of the network is made, and all the accessible systems (either directly or by means of other systems). This description is mandatory and up to 512 systems can be configured. Communications objects related to remote systems described within the basic network configuration are statically configured; that is, when this configuration is enabled:

• they are immediately available to the communications servers at connection request time • they remain available during all the communications session • they cannot be deleted, added or modified during the communications session which has enabled them.

Directory of Remote Systems All or some of the remote systems may be described separately in the remote system dictionary which is part of the directory configuration. Up to 5000 systems can be declared. Communications objects related to remote systems described in the enabled directory configuration are dynamically configured, namely:

• they are dynamically created from directory information at each connection request time or upon each request from an operator command • they are not kept in memory after being used • all the directory information dealing with the remote systems can be deleted, added or modified during a communications session using incremental enabling.

4-2 47 A4 92UC Rev03 GCOS 7 View of the Network

The advantage of incremental enabling is that the remote systems can be declared in the directory rather than in the basic network configuration. When this description is missing or empty, the generation processing will result in an empty directory. Subdomain objects can also be addressed in this directory: they describe specific subnetworks where all the systems share the same NSAP-prefix. See Section 5.

Directory Service of Correspondents This part describes all the objects concerning the communications service of correspondents. This description is optional but when present, is always included in the correspondent dictionary which is part of the directory configuration. Up to 10000 correspondents can be declared. The information related to the service of correspondents may be modified during a communications session using incremental generation and incremental enabling. Correspondents are taken into account dynamically, whereas information specific to TDS such as workstations and pools are taken into account only at cold start of the application concerned.

4.2.2 Network Configurations

An ISO network configuration primarily describes a collection of systems or nodes mutually interconnected by communications links, and how to establish these links. A system is declared by a single directive which namely specifies its type and network address. Using detailed low level description, each communications object may be declared separately by its own low level directive. The objects defined at network generation may be subsequently accessed by operator commands. Each system is described by a unique SYS (SYSTEM) directive. There are therefore as many SYS directives as there are systems to be described.

47 A4 92UC Rev03 4-3 Network Overview and Concepts

Using the SYS directive, the user has to supply for each system only its name and its functional relationship in the network by means of one of the following attributes for each kind of system: Local System: DSA or ISO address, lan-attributes Passthrough: DSA or ISO address, psi-channel address or DSA or ISO address, lan-attributes Neighbor: DSA or ISO address, lan-attributes Remote System: DSA or ISO address Session Routes: names of servers and RTS Subdomain: NSAP prefix, list-of-systems PSI channel address: psi-controller name. ISL access: LAN controller name. OCS access: OCS controller name. The descriptions of the local system, neighbors and passthroughs are mandatory because of their physical addresses (PSI or LAN). Remote Systems still need to be configured but only when migrating network from the DSA world to that of ISO. OSI addressing itself no longer requires these systems to be configured. Subdomains are used only to restrict the list of passthroughs for outward connections. The DEFAULT directive allows changing the setting of specific protocol or administrative attributes such as timer and retry-count which are common to several systems.

NOTES: 1. Some low-level directives describing basic internal objects are also available when specific needs on network configuration are necessary. See the manual Network Generation. 2. These low-level objects are also managed by DSAC administration. 3. DSA informations such as SCID (DSA200 address) still remain necessary for managing the administrative functions of the passthrough namely, SYSGEN, LOAD and DUMP of the Datanet and the CNP7.

4-4 47 A4 92UC Rev03 GCOS 7 View of the Network

4.3 OCS Front End Configuration

An OCS Front End is configured when the corresponding OCS server is started. The configuration step consists of loading the configuration parameters necessary for the execution of the transport protocols, namely:

• Names of the systems in the network • The routes used to access the remote systems thru the transport mechanisms • The gateway systems used to access a remote system • The network addresses of the remote systems NETGEN and OCS Front End configuration directives are described in the Network Generation manual.

47 A4 92UC Rev03 4-5 Network Overview and Concepts

❑

4-6 47 A4 92UC Rev03 5. GCOS 7 Network Administration

5.1 ISO/DSA and ISO Administration

DSAC (Distributed System Administration and Control) allows GCOS 7 to administer an ISO/DSA or ISO network. The RAEH (Remote Administrative Exchange Handler) server provides the DSAC services. The DSAC services are: • receiving a command from any system, local or remote and sending back the resulting response. • sending a command from the local system for execution in another ISO/DSA system and receiving the response. • journalizing events (sent by the local or remote systems) concerning the network behaviour. • reporting and monitoring the events to operators. All these functions are described in the manual DSAC User’s Guide. Commands and events are described in the manual Network User Guide.

5.2 IPS Administration

The FCP7 IPS stack administration consists of:

• a set of local commands allowing to display (or modify) network parameters, routing tables and statistics. • a SNMP agent, located in the OCS driver, allowing a remote or local SNMP manager to manage the IPS communications of the FCP7. • a SNMP manager, located in the OCS driver, able to administer a local SNMP agent (that is, in the same driver), or a remote SNMP agent. All these functions are described in the manual Network User Guide.

47 A4 92UC Rev03 5-1 Network Overview and Concepts

5.3 OCS Front End Management

The OCS Front End configuration loading and dump is performed when the OCS server is started according to the commands included in a scenario file.

The OCS Front End configuration consists in loading in this OCS Front End all the necessary parameters for communication protocols execution. These parameters are described in specific files referenced in the load scenario.

Configuration and dump processing for the OCS Front End are described in the Network User Guide manual.

5.4 Administrative Function for FEP’s

Administrative functions for Datanet and CNP7 are GENERATION, LOAD and DUMP of the FEP. Administrative functions are managed on GCOS 7 by the FECM server. These functions are invoked via scenario files when an FECM server is started for the system to be administered. The administrative functions for Datanet and CNP7 are described in the manual Network User Guide.

The administrative functions for the MainWay are executed from the MainWay Service processor (SP).

5.5 Administrative Function for MainWay 2600LE

Administrative functions for MainWay 2600LE are GENERATION, LOAD and DUMP. Administrative functions are managed on GCOS 7 by the FECM and TNS servers. These functions are invoked via scenario files when an FECM server is started for the system to be administered.

The administrative functions for MainWay 2600LE are described in the manual MainWay 2600LE User’s Guide and Network User’s Guide.

5-2 47 A4 92UC Rev03 Glossary

This glossary defines terms used in the GCOS 7 communications environment. Abbreviations in the form of acronyms used in text of this manual.

Concepts and Terminology

A ADDRESSING PID It is the part of the PID module which is in charge of converting the session addressing from DSA to ISO, and vice versa.

B BASIC NETWORK CONFIGURATION Part of the network configuration which must always be present and cannot be swapped during a communications session. BASIC NETWORK CONFIGURATION DESCRIPTION Set of directives describing the local system, its passthroughs and neighbors and possibly some remote systems. It may also comprise network administration and queue descriptions. It is embedded between NETWORK and ENDNETWORK directives. BASIC NETWORK DICTIONARY Dictionary which contains the names and locations of all communications objects statically configured and produced by a basic generation. BASIC NETWORK GENERATION NETGEN processing applied to a basic network configuration description. This processing can normally be executed while a communications session is running. However, its enabling requires the communications session to be previously stopped.

47 A4 92UC Rev03 g-1 Network Overview and Concepts

C COMMUNICATIONS SESSION The activity state of the configurations enabled in the running workspace. The session is considered in progress if at least: • one communications server is active in the used state • one network operator command is still executing • one application such as TDS or MCS is still using VCAM. Otherwise the session is considered completed. CONFIGURATION Data resulting of the NETGEN generation processing applied to configuration description directives. A full set of configurations comprises: • the basic network configuration • the directory configuration • and the terminal configuration. CONFIGURATION DIRECTORY Part of the network configuration which is optional and moreover can be fully changed or suppressed during a communications session. It always contains the two dictionaries even if they are empty. A basic network generation without directory configuration description results in an empty directory configuration available for any subsequent incremental generation. CORRESPONDENT In general terms, it is a local representation of a remote object, function or application associated with a name and a type, and network references to access it. CORRESPONDENTS DICTIONARY Dictionary which contains all the objects dealing with the communications service of correspondents which are produced by a directory generation. It can be empty.

D DICTIONARY Container filled with information related to each communications object generated. There are 3 different dictionaries: • the basic network dictionary (DDICT), • the correspondent dictionary (TCORR), • the remote system dictionary (TSYS ), with the last two forming the directory. DIRECTIVE A statement describing one communications object or system and its relationship with others. When describing an object rather than a system it is then called low-level directive.

g-2 47 A4 92UC Rev03 Glossary

DIRECTORY It consists of two dictionaries: • the remote-system dictionary (TSYS) • the correspondent dictionary (TCORR). DIRECTORY CONFIGURATION DESCRIPTION It must be embedded between DIRECTORY and ENDDIRECTORY directives. It is mainly composed of two parts in any order: Correspondent Description: Contains all the objects dealing with the communications service of correspondents. This description is optional, when present the generated objects are always all included into the correspondent dictionary (maximum 10000 correspondents). Remote-system Description: Contains all or some remote systems up to 5000, accessible by the local system using passthroughs already described in the basic configuration. DIRECTORY GENERATION NETGEN processing applied to a DIRECTORY configuration description. It can be: • either associated with a basic generation, in which case it is enabled when the basic generation is enabled • or launched separately, in which case it is incremental and its enabling requires a valid basic configuration to be already enabled. Directory generation may result in an empty directory if the directory configuration description is empty.

F FCP7 FDDI Communications Processor 7 is an integrated communications controller which enables a DPS 7000 to access an FDDI network. FCP7 contains both an OSI stack and an IPS stack. The OSI stack contains OSI layers 1 to 4 and serves both OSI and DIWS. The IPS stack contains the TCP, UDP, ICMP, and IP layers. The communications server associated with FCP7 is OCS (Open Communications Subsystem). FCP7 contains an RFC1006 transport layer enabling OSI/DIWS sessions to be run over a TCP/IP network. FRONT-END PROCESSOR See pass-through. FTP FTP (File Transfer Protocol) is a "de facto" TCP/IP standard for file transfers.

47 A4 92UC Rev03 g-3 Network Overview and Concepts

G GXTI GXTI is a programmatic interface which allows a GCOS 7 application to access a remote application through ISO transport or TCP or UDP transport.

H HETEROGENEOUS SYSTEM System which can exchange administrative information in the form of commands and responses, and messages with the local system only in AEP (Administrative Exchange Protocol) format. Such a system can be any including another DPS 7000 running on releases prior to V6. HOMOGENEOUS SYSTEM System which can exchange administrative information in the form of commands and responses, and messages with the local system in GCOS format with the exception of AUTs which always use AEP format. Such a system can only be a DPS 7000 running on releases from V6 onwards.

I ISO-DSA PLUG See PID.

L LAN Extender Subsystem In addition to the FCP7, the LAN Extender Subsystem provides a maximum configuration of 5 FDDI SAS links, 8 Ethernet 802.3 ports, and 1 FDDI DAS link. LOCAL SYSTEM The unique DPS 7000 system running on GCOS-7 versions from V6 onwards for which the local view of the network is generated. It must be described before any other system.

N NEIGHBOR Any system directly accessible from the local system, and linked to it either by a PSI channel (Datanet) or by a Local Area Network directly connected to the local system. NETWORK The most general term describing intercommunication between nodes and nodes, and nodes and end-users. The term may also have the more restrictive scope of the ISO network layer environment.

g-4 47 A4 92UC Rev03 Glossary

NETWORK ADMINISTRATION Set of communications functions which regulate, monitor and control events in the network. NETWORK ADMINISTRATION DESCRIPTION The part of the basic network description which declares local and remote administrative objects. This description is optional since default administrative objects are implicitly supplied. NETWORK CONFIGURATION The resultant data output by the NETGEN utility from the input network description directives. It is composed of: • the basic network configuration • and the directory configuration. NETWORK CONFIGURATION DESCRIPTION Set of directives fully describing all the communications objects involved within the whole network which are accessible by the local system. It always comprises a basic network configuration description and where applicable, a directory configuration description. The basic network configuration description describes the view of the network from the standpoint of the local DPS 7000 which accesses all the systems in the network either directly or by means of other systems. This description is mandatory and can contain up to 512 systems. All or some of the remote systems, up to 5000, may be described separately in the remote system dictionary which forms part of the directory configuration. NFS NFS (Network File System) is a distributed file access facility. It supports client/server architecture. An NFS client accesses files, an NFS server provides files for access. NODE Synonymous with system.

O OCS OCS (Open Communications Subsystem) is the communication server associated to OCS Front Ends which are FCP7 (FDDI Communication Processor 7) for DPS 7000 and VCP7 (Virtual Communication Processor 7) + network Adapter for DPS 7000/XTA. OPEN LAN ACCESS 7 OPEN LAN ACCESS 7 is a communications module which handles the protocol and/or address conversion from DSA to ISO. This mechanism allows DSA applications such as IOF, TDS, UFT to work with applications located in an ISO/DSA workstation (DIWS).

47 A4 92UC Rev03 g-5 Network Overview and Concepts

P PASSTHROUGH A neighbor acting as an intermediate thru which the local system accesses remote systems or other networks, and vice versa. Such a system front-ends the local system and acts as a go-between with remote systems. PID The ISO/DSA plug module which interface between VCAM session and the Transport servers to allow the DSA applications to communicate with applications running on ISO/DSA work stations (DIWS). PROTOCOLAR PID The part of the PID module in charge of converting session protocols from DSA to ISO, and vice versa.

R REMOTE SYSTEM Any system which the local system accesses through the intermediary of a passthrough. The directive which describes it must appear after all the passthroughs.

S SYSTEM The functional position occupied by the system within the current network configuration determines its functional type, namely, local system, passthrough, neighbor or remote system.

g-6 47 A4 92UC Rev03 Glossary

List of Abbreviations AFI Authority and Format Identifier (OSI addressing) API Application Programmatic Interface CNP7 Communication Network Processor for the DPS 7000 CNS7 Communication Network Software for the CNP7 CRNG CReate_Network_Generation GCL command (CRNETGEN) CSMA/CD Carrier Sense Multiple Access/Collision Detection DIWS DSA-ISO Work Station DJP Distributed Job Processing DN DataNet DNS Distributed Network Supervisor (Datanet software) DPS Distributed Processing System (GCOS) DPX Distributed Processing System (UNIX) DSA Distributed Systems Architecture DSAC Distributed Systems Administration and Control DSP Domain Specific Part of NSAP (OSI addressing) EAnn Ethernet Adaptor for ISL FCP7 FDDI Communications Processor 7 FDDI Fiber Distributed Data Interface FECM Front End Control Manager (communications server) FEP Front End Processor FEPS Front End Processor Support (communications server) FTAM File Transfer Access Method GCOS General Comprehensive Operating System ICMP IP Control Message Protocol

47 A4 92UC Rev03 g-7 Network Overview and Concepts

IDI Initial Domain Identifier of NSAP (OSI addressing) IDP 1. Initial Domain Part of NSAP (OSI addressing) 2. ISO / DSA Plug (DSA to ISO migration) IEEE Institute of Electrical and Electronic Engineers IOF Interactive Operator Facility IP Internet Protocol (network layer) IPS Internet Protocol Suite (UDP-TCP/IP) ISL Inter System Link (applicable to DPS7000) ISO International Standards Organization LAN Local Area Network LCT Local Controller (LOCCTLR) named EAnn or CCnn LNA Local Network Adaptor LNM Local Network Manager (for DPS 7000/Ax) LNI Local Network Interface (for DPS 7000/4xx) LPL Local Physical Link (LOCPLINK) LSAP Link Service Access Point (OSI addressing) LSC Local Session Control (LOCSESS) LSYS Local System (LOCSYSTEM) LT Logical Terminator (LTERMINATOR) LTS Local Transport Station, addressed by TSAP MAC Media Access Control (link sub-layer for LAN) NG Network Generation utility for DPS7 (NETGEN) NPDU Network Protocol Data Unit (ISO/DSA addressing) NR Network Route (NETROUTE) NSAP Network Service Access Point (OSI addressing) NSDU Network Service Data Unit (OSI addressing) OCS Open Communication Subsystem

g-8 47 A4 92UC Rev03 Glossary

OPEN7 OPEN GCOS7 towards TCP/IP communications protocols OSF Open Systems Facility OSI Open Systems Interconnection PDU OSI layer Protocol Data Unit PID (French acronym for ISO-DSA Plug) PIDa Addressing PID (DSA to ISO migration) PIDp Protocolar PID (DSA to ISO migration) PPDU Presentation Protocol Data Unit PSAP Presentation Service Access Point (OSI addressing) PSDU Presentation Service Data Unit (OSI addressing) PSEL Presentation layer SELector (OSI addressing) PSI Peripheral Subsystem Interface QOS Quality Of Service (OSI addressing) RAEH Remote Administrative Exchange Handler (DSAC) RCT Remote ConTroller (RMTCTLR) RFC1006 Internet community document (and by extension, the layer) defining an OSI session over TCP/IP layers. The RFC1006 layer is a class 0 transport layer. RSC Remote Session Control (RMTSESS) RSP Response, DSAC concept RSYS Remote System (RMTSYSTEM) RTS Remote Transport Station (RMTTRANSPORT) SA ISO Addressing Subdomain (SDOM) SAP layer Service Access Point (OSI addressing) SC Session Control SCID Session Control Identifier SDU Service Data Unit (OSI addressing)

47 A4 92UC Rev03 g-9 Network Overview and Concepts

SEL layer SELector (OSI addressing) SID ISO/DSA Specification SNPA SubNetwork Point of Attachment (OSI addressing) SNMP Simple Network Management Protocol SPA Service Processor Ares, applicable to DPS 7000 SPDU Session Protocol Data Unit (OSI addressing) SR Session Route (SESSROUTE) SSAP Session Service Access Point SSDU Session Service Data Unit (OSI addressing) SSEL Session layer SELector (OSI addressing) STID (French acronym for DIWS) SVR Server SYS System SYSGEN System Generation for DNS and CNS 7 TCP Transmission Control Protocol (UNIX transport) TDS Transaction Driven Subsystem TM Terminal Manager TNS Transport and Network Subsystem (comms server) TP 1. Transport Protocol (TPROTOCOL) 2. Transaction Program (XCP2 or TDS environment) TPDU Transport Protocol Data Unit (ISO/DSA addressing) TPI Transport Programmatic Interface TRAILn TRAILing TCP/IP headers protocol (TCP/IP) TSAP Transport Service Access Point (OSI addressing) TSDU Transport Service Data Unit (OSI addressing) TSEL Transport layer SELector (OSI addressing) TSI Transport Session Interface

g-10 47 A4 92UC Rev03 Glossary

TSYS 1. Telecommunication remote SYStem dictionary 2. Terminate SYStem main operator command UDP User Datagram Protocol (UNIX transport) UFT Unified File Transfer, file transfer using DSA protocol RFA UM Unsolicited Message (DSAC) UT User of Transport (OSI addressing) VCAM Virtual Communications Access Method (session communication server) VCP7 Virtual Communication Processor: it is the software adaptation of an OCS Front End for DPS 7000/XTA system WAN Wide Area Network XCP Extended Cooperative Protocol XOPEN Open to UNIX facilities XTA eXtended Twin Architecture XTI XOPEN Transport Interface

47 A4 92UC Rev03 g-11 Network Overview and Concepts

g-12 47 A4 92UC Rev03 Index

connection mechanism (Con’t) outward connectionless mode...... 2-37 A outward FEPS pseudo-transport ...... 2-35 outward network routing...... 2-37 addressing outward session routing ...... 2-32 function of lower layers...... 2-10 outward TNS transport ...... 2-37, 2-40 function of LSAP in ISO/DSA...... 2-10 selecting upper layers ...... 2-36 function of mailbox in DSA...... 2-10 selecting upper layers in inward ...... 2-40 function of SCID in ISO/DSA...... 2-10 setting of frame in outward.....2-38, 2-40 function of TSAP in ISO/DSA ...... 2-10 correspondent ISO/DSA ...... 2-10 declaring TM ...... 4-3 OSI ...... 2-13 TCP/IP...... 3-4 declaring XCP...... 4-3 AET CSMA/CD...... 3-3 application entity title...... 2-21 AFI D component of IDP ...... 2-15 data link layer ISO/DSA...... 2-9 B TCP/IP ...... 3-3 basic network directory composition ...... 4-1 remote systems...... 4-2 description ...... 4-2 DSP component of NSAP...... 2-16 domain specific part...... 2-16 C commands...... 1-12 F communications description of servers ...... 1-9 FCP7 ...... 1-7 TCP/IP...... 3-1 FDDI ...... 3-3 connection mechanism FECM inward...... 2-38, 2-41 description ...... 1-9 inward frame reception by TNS ...... 2-38 FEPS inward from link layer...... 2-38 description ...... 1-9 inward from network layer...... 2-39 use for ISO session ...... 2-29 inward function of DNS ...... 2-36 FIA ...... 1-6 inward function of TNS...... 2-38, 2-41 FTP...... 3-2 ISO session in inward...... 2-41

47 A4 92UC Rev03 i-1 Network Overview and Concepts

G M GXTI MAC sub-layer description ...... 1-10 ISO/DSA...... 2-9 TCP/IP ...... 3-3 MainWay 2600...... 1-8 I MPC...... 1-6 IDI component of IDP ...... 2-16 N initial domain identifier...... 2-16 IDP NETGEN...... 1-11 component of NSAP...... 2-15 network inward connection mechanism 2-35, 2-38, 2-41 examples of configurations...... 1-3 IP protocol ...... 3-3 ISO configurations...... 4-3 ISL ...... 1-1, 1-6 network layer administration of connection...... 3-10 ISO/DSA...... 2-8 ISO TCP/IP ...... 3-3 network configurations...... 4-3 NFS ...... 3-2 ISO/DSA NSAP addressing...... 2-10, 2-23 OSI address description ...... 2-15 application layer ...... 2-5 special format for RFC1006 ...... 2-19 transport layer...... 2-6 ISO-DSA plug functions...... 2-23 O OCS L description ...... 1-9 OPEN LAN ACCESS 7 LAPB...... 3-3 description ...... 1-10 layer OSI addressing ISO/DSA implementation ...... 2-5 selector...... 2-14 ISO/DSA presentation...... 2-5 service access point...... 2-14 TCP/IP application ...... 3-2 TCP/IP data link ...... 3-3 TCP/IP network...... 3-3 P TCP/IP physical...... 3-3 physical layer TCP/IP presentation ...... 3-2 TCP/IP ...... 3-3 TCP/IP session ...... 3-2 PID TCP/IP transport...... 3-2 address conversion mechanism...... 2-25 LLC sub-layer functions ...... 2-23 ISO/DSA ...... 2-9 protocol conversion mechanism ...... 2-24 LLC1 sub-layer presentation layer TCP/IP...... 3-3 TCP/IP ...... 3-2 LNI ...... 1-6 PSAP address LNM ...... 1-6 description ...... 2-21

i-2 47 A4 92UC Rev03 Index

Q Telnet...... 3-2 TNS QMON description ...... 1-9 description ...... 1-9 extension for ISO session ...... 2-29 QOS implementation of ISO layers...... 3-10 quality of service ...... 2-34 implementation of transport...... 2-29 Token Bus ...... 3-3 Token Ring...... 3-3 R transport RAEH connection...... 2-6 description ...... 1-9 connection through GXTI...... 2-42 RFC1006 transport layer description ...... 1-11 TCP/IP ...... 3-2 transport layer...... 2-7 TSAP Transport Service Access Point ...... 2-10 TSAP address S description ...... 2-20 TSEL SCID...... 2-10 transport selector...... 2-20 Session Control Identifier...... 2-10 session layer ISO/DSA ...... 2-5 U TCP/IP...... 3-2 SMTP...... 3-2 UDP transport ...... 3-2 SNMP ...... 3-2 SPA...... 1-6 V SSAP address description ...... 2-21 VCAM subdomain description ...... 1-10 routing ...... 2-33 function...... 2-3 system VCP7...... 2-11 declaring in ISO ...... 4-3 VCP7 Controller ...... 1-7

T X TCP transport...... 3-2 X25...... 3-3 TCP/IP administration of connection ...... 3-10 addressing...... 3-4 XTI...... 3-2 application layer ...... 3-2 data link layer...... 3-3 description ...... 1-11 network layer...... 3-3 overview...... 3-1 physical layer ...... 3-3 presentation layer ...... 3-2 session layer ...... 3-2 transport layer...... 3-2

47 A4 92UC Rev03 i-3 Network Overview and Concepts

i-4 47 A4 92UC Rev03 Technical publication remarks form

Title : DPS7000/XTA NOVASCALE 7000 Network Overview and Concepts Communications: FCP7

Reference Nº : 47 A2 92UC 03 Date: August 2002

ERRORS IN PUBLICATION

SUGGESTIONS FOR IMPROVEMENT TO PUBLICATION

Your comments will be promptly investigated by qualified technical personnel and action will be taken as required. If you require a written reply, please include your complete mailing address below.

NAME : Date : COMPANY : ADDRESS :

Please give this technical publication remarks form to your BULL representative or mail to:

Bull - Documentation Dept. 1 Rue de Provence BP 208 38432 ECHIROLLES CEDEX FRANCE [email protected] Technical publications ordering form

To order additional publications, please fill in a copy of this form and send it via mail to:

BULL CEDOC 357 AVENUE PATTON Phone: +33 (0) 2 41 73 72 66 B.P.20845 FAX: +33 (0) 2 41 73 70 66 49008 ANGERS CEDEX 01 E-Mail: [email protected] FRANCE

CEDOC Reference # Designation Qty

______[ _ _ ]

[ _ _ ] : The latest revision will be provided if no revision number is given.

NAME: Date: COMPANY: ADDRESS:

PHONE: FAX: E-MAIL:

For Bull Subsidiaries: Identification:

For Bull Affiliated Customers: Customer Code:

For Bull Internal Customers: Budgetary Section:

For Others: Please ask your Bull representative.

BULL CEDOC 357 AVENUE PATTON B.P.20845 49008 ANGERS CEDEX 01 FRANCE

REFERENCE 47 A2 92UC 03