Network Overview and Concepts - support.bull.comsupport.bull.com/ols/product/system/gcos7/gcos7-com/g7-dps7000/… · 47 A4 92UC Rev02 Communications Bull DPS 7000 Network Overview

47 A4 92UC Rev02

Communications

Bull DPS 7000

Network Overview and Concepts

Subject: This manual gives an overview of networking as implementedon DPS 7000 systems.

Special Instructions:

Software Supported: GCOS 7-V9 (Technical Status TS9866 or later)

Software/Hardware required:

Date: December 2000

Bull S.A.CEDOCAtelier de reprographie357, Avenue Patton BP 2084549008 ANGERS Cedex 01FRANCE

Bull HN Information Systems Inc.Publication Order EntryFAX: (800) 611-6030MA30/415300 Concord Rd.Billerica, MA 01821U.S.A.

47 A4 92UC Rev02

Copyright © Bull S.A., 1995, 1996, 2000

Bull acknowledges the rights of proprietors of trademarks mentioned herein.

Your suggestions and criticisms concerning the form, contents and presentation of this manual are invited.A form is provided at the end of this manual for this purpose.

No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by anymeans, electronic, mechanical or otherwise without the prior written permission of the publisher.

Bull disclaims the implied warranties of merchantability and fitness for a particular purpose and makes noexpress warranties except as may be stated in its written agreement with and for its customer. In no event is Bullliable to anyone for any indirect, special, or consequential damages.The information and specifications in this document are subject to change without notice.Consult your Bull Marketing Representative for product or service availability.

47 A4 92UC Rev02 iii

Preface

This manual gives an overview of communications architecture for the DPS 7000.

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 inparticular, communications as implemented for the DPS 7000.

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

Datanet and CNP7:

DNS V4 System Generation .................................................................... 39 A2 22DNCNS 7 System Generation....................................................................... 39A2-40DM

Transport and Session Servers:

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

Network Installation, Operation and Administration:

Getting Started with your Telecommunications ...................................... 47 A2 70UCNetwork Generation................................................................................ 47 A2 93UCNetwork User Guide ............................................................................... 47 A2 94UCDSAC User’s Guide ................................................................................ 47 A2 75UCAUPI User’s Guide ................................................................................. 47 A2 76UC

Scope andObjectives

Bibliography


iv 47 A4 92UC Rev02

Service of Correspondents:

Transactional Intercommunication using XCP1 User’s Guide................ 47 A2 11UTCPI-C/XCP2 User’s Guide ......................................................................47 A2 14UTTDS Administrator’s Guide......................................................................47 A2 20UT

MainWay 2000 Documents:

For a list of MainWay 2000 documents, see:

MainWay Overview.................................................................................. 39 A4 14EB

Other Documents:

INET Reference Manual ..........................................................................13 A2 12SMINET User Guide .....................................................................................13 A2 13SMMCS User’s Guide .................................................................................. 47 A2 32UCTCP/IP 7 End-User’s Guide .................................................................... 47 A2 30USOPEN 7 Administrator’s Reference Manual ............................................ 47 A2 31USOPEN 7 Administrator’s Guide ............................................................... 47 A2 32US

The following notation conventions are used in this manual when describing thesyntax of commands:

UPPERCASE The keyword item must be coded exactly as shown.

Lowercase Indicates a user-supplied parameter value. Thesymbolic name digitsn is used to represent a string ofdecimal digits of maximum length n.

[item] An item within square brackets is optional.

{item 1} A column of items within braces means that one valuemust

{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 thanone item.

. . . An ellipsis indicates that the preceding item may berepeated one or more times.

SyntaxNotation

47 A4 92UC Rev02 v

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 2000, Datanet, and CNP7.................................................................. 1-6

1.3.2 ISL Controller ..................................................................................................... 1-6

1.3.3 FCP7 and VCP7 Controllers.............................................................................. 1-71.3.3.1 FCP7 Controller................................................................................. 1-71.3.3.2 VCP7 Controller................................................................................. 1-7

1.3.4 MainWay 2000 ................................................................................................... 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


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2.4 OSI Addressing Concepts............................................................................................. 2-13

2.4.1 General Structure............................................................................................. 2-14

2.4.2 Network Layer Addressing: NSAP Address..................................................... 2-15

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...................................................... 2-302.9.1.1 Introduction...................................................................................... 2-302.9.1.2 Outward Connection Mechanism .................................................... 2-302.9.1.3 Inward Connection Mechanism....................................................... 2-32

2.9.2 ISO Session Connection Mechanism .............................................................. 2-322.9.2.1 Introduction...................................................................................... 2-322.9.2.2 Outward Connection Mechanism .................................................... 2-322.9.2.3 Inward Connection Mechanism....................................................... 2-35

2.9.3 FEPS Pseudo-Transport.................................................................................. 2-352.9.3.1 Inward Connections......................................................................... 2-352.9.3.2 Outward Connections...................................................................... 2-36

2.9.4 TNS Connections............................................................................................. 2-372.9.4.1 Outward Connections...................................................................... 2-372.9.4.2 Inward Connections......................................................................... 2-38

2.9.5 OCS Connections ............................................................................................ 2-402.9.5.1 Outward Connections...................................................................... 2-402.9.5.2 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

47 A4 92UC Rev02 vii

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

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 on commodity Decor .................................................. 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

Glossary

Index


viii 47 A4 92UC Rev02

47 A4 92UC Rev02 ix

Table of Graphics

1-1. DPS 7000 Communications Architecture for DPS 7000 running in Bull Decor .............. 1-41-2. Communication Architecture for DPS 7000 running in commodity Decor ...................... 1-52-1. DSA/ISO Layers .............................................................................................................. 2-22-2. DSA/ISO Layer Implementation on DPS 7 running in Bull Decor................................... 2-32-3. DSA/ISO Layer Implementation on DPS 7000 running in commodity Decor ................. 2-42-4. ISO Transport Connection .............................................................................................. 2-72-5. DSA Applications Communicating via the RFC1006 Transport...................................... 2-82-6. DSA/ISO Communications Controller ............................................................................. 2-92-7. DSA/ISO Address Configuration ................................................................................... 2-122-8. OSI PSAP Address Structure........................................................................................ 2-142-9. OSI NSAP Address Structure ....................................................................................... 2-152-10. AFI Values in OSI NSAP Address................................................................................. 2-162-11. DSP Values in OSI NSAP Address............................................................................... 2-172-12. Field Lengths in OSI NSAP Address............................................................................. 2-182-13. Example of RFC1006 NSAP Address Format .............................................................. 2-202-14. ISO-DSA Plug (PID) Functions ..................................................................................... 2-242-15. Examples of TSELs in the DPS 7000 ........................................................................... 2-262-16. Two Systems with the Same TSEL............................................................................... 2-262-17. Two Systems with Different TSELs............................................................................... 2-272-18. PIDp Generation Example ............................................................................................ 2-272-19. PIDa Generation Example ............................................................................................ 2-282-20. ISO Quality of Service................................................................................................... 2-343-1. TCP/IP Layered Architecture .......................................................................................... 3-13-2. IP Address Format .......................................................................................................... 3-43-3. TCP/IP via FCP7............................................................................................................. 3-73-4. TCP/IP Access via OPEN7 ............................................................................................. 3-93-5. TCP/IP via INTEROP7 on commodity decor ................................................................ 3-12

Figures


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47 A4 92UC Rev02 1-1

1. Introduction

Bull GCOS 7 communications software provides the means to communicate withother GCOS or non-GCOS systems via a local or a long-distance network. Thismanual 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-SystemLink), or use Communication Processors with FDDI or High speed Ethernetadapters, or require one or several FEP (Front End Processors) and CommunicationControllers to manage terminals or stations and provide gateways to any of theabove-listed network environments.


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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 detravail ISO/DSA ”), which is a station executing DSA application on the OSIsession

• Availability of OSI session programmatic interface

• Availability of GXTI programmatic interface (GCOS7 X/OPEN TransportInterface)

• Support of LU6.2 connections (XCP2 module) through the DSA-SNA gatewayor 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 (OpenCommunication Subsystem).

Introduction

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1.3 DPS 7000 Communications Architecture

The DPS 7000 communication environment may require one or several front EndProcessors (FEP) to manage terminals, stations and/or to access networks. Sinceterminals are managed by the FEP, they are not declared in the DPS 7000 networkgeneration but, instead, they are declared in the system generation (SYSGEN) ofthe 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 theDPS 7000

• MainWay (current Bull offer) which is connected to the DPS 7000 thru an OCSconnection which is either FDDI or fast Ethernet

DPS 7000 communication environment allows also direct access to Local AreaNetworks , without making use of FEP’s, when the FEP’s specific functions are notused (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 processorsvia 10 Mbits Ethernet

− Access thru OCS controller to stations, systems and communicationprocessors via 100 Mbits FDDI

• On DPS 7000 running commodity CPU’s:

Access thru OCS controller to stations, systems and communication processorsvia Local area Network (e.g.: Fast Ethernet)

DPS 7000 communications are handled by software modules namedcommunication servers, as described below:

• Figure 1-1 shows the basic communication architecture for DPS 7000 running inBull Decor

• Figure 1-2 shows the basic communication architecture for DPS 7000 running incommodity Decor


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DPS 7000

LE7

XTI Applications

VCAM-ISO VCAM-DSAGXTI

OpenLANAccess

FEPS OCS GXTID

ISO Transport

Null Internet

TNS

FDDI Access

NullInternet

FullInternet

ISO Transport

Open7TCP/IPCommunications

FCP7

IP

UDPTCP

ISLController

ISL

CNP7Datanet

WANEthernet

FDDI DAS

RFC1006

FDDI SAS

MainWay 2000

ICMP

Open7 Applications(FTP, NFS, TELNET, ...)

ISO Applications(FTAM, X400)

DSA Applications(IOF, TDS, UFT, ...)

Figure 1-1. DPS 7000 Communications Architecture for DPS 7000 runningin Bull Decor

Introduction

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DPS7000

GCOS7 applications using thetelecommunications

GCOS7

SOCKG7

VCAM (session layer)

OCS

TCP/IP Driver

EXTENDED

VIRTUAL MACHINE

VIRTUALMACHINE

VCP7

(telecomtransport &

networkprotocols)

VCP7

1 to 4 VCP7

MAINWAY

Primary Network

Secondary Network

Local AreaNetworks

Fast Ethernet

EthernetController

EthernetController

EthernetController

COMMODITY SOFTWARE

Open LAN Access (PID)

Figure 1-2. Communication Architecture for DPS 7000 running incommodity Decor


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1.3.1 MainWay 2000, Datanet, and CNP7

The DPS 7000 can connect to the network through:

• a MainWay 2000 and its LAN Extender via the OCS server module and anFDDI 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 anEthernet 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 ISLcable.

1.3.2 ISL Controller

The ISL controller also allows the DPS 7000 to connect directly over an Ethernetlink 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.

Introduction

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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 overTCP/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 protectorwhen 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 bewritten. This address is not related to the controller’s serial number. FCP7 MACaddresses are in the range 08 00 38 10 00 10 to 08 00 38 10 0F DF. Once the MACaddress has been assigned, it should be written on the label. The label is then stuckon the appropriate DPS 7000 rack (in which the FCP7 is placed).

1.3.3.2 VCP7 Controller

On a DPS 7000 running in commodity Decor, FCP7 controller is replaced by avirtual controller: VCP7, which handles Transport and Network communicationlayers in the same way as they are handled by FCP7 on a DPS 7000 running inBull Decor, and executing with the addition of an Adapter card and its associateddriver, the same set of communication functions, as these globally executed byFCP7.


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1.3.4 MainWay 2000

The MainWay 2000 includes the LAN Extender Subsystem and one or more WANProcessor Modules giving access to the WAN network via either OSI/DSA,OSF/SNA, or TCP/IP protocols.

Introduction

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1.4 Communications Servers

The main communications functions are handled by communications servers whichare implemented as independent subsystems.

The communication servers are:

• TNS, a unique server that handles communications over one or several ISLcontrollers, allowing communications over one or several ISL cables. There isonly one occurrence of TNS in a DPS 7000 system. TNS manages allconnections with other systems either directly or through CNP7. The TNSconfiguration parameters are specified at network generation.

• FEPS, a server that handles the dialog with a Datanet through 1 or 2 PSIchannels. There is one occurrence of FEPS in a DPS 7000 system for eachDatanet attached. In the case of a bi-PSI link towards a single Datanet, only onePSI channel is managed by the FEPS occurrence at a time, the other occurrencebeing backup. FEPS manages the two PSI links so that it automatically, restartsin a transparent way on the other PSI when the first fails. Each FEPS occurrencemust be defined at network generation.

• OCS is the communication driver which is common to DPS 7000 running inBull Decor and in commodity Decor, it drives as well FCP7’s as VCP7’sdepending upon the DPS 7000 platform. OCS is a single driver which handlesup to 4 server instances (one per OCS Front End). OCS also performsadministrative functions for OCS Front End such as memory dump (DUMP) orload (LOAD). The OCS configuration parameters are specified at networkgeneration.

• FECM, a server that performs administrative functions such as LOAD, DUMPor SYSGEN for the Datanet and the CNP7. It does not need to be configuredand an occurrence of FECM is dynamically created when a Datanet or a CNP7 isto be administered.

• RAEH, a unique server that handles administrative sessions between DSAsystems for the purpose of exchanging commands/responses or eventnotifications.

• QMON, a unique server that manages queues accessed by applications using theMCS communications interface.


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1.5 VCAM

VCAM is a communications module which handles the functions dealing with thesession layer (connections between local or remote applications using ISOISO/DSA or DSA protocols and addressing). Starting and terminating thiscommunications module is synchronized with those of GCOS 7 itself. But onlylocal 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 protocoland/or address conversion from DSA to ISO. This mechanism allows DSAapplications such as IOF, TDS, UFT to work with applications located in anISO/DSA workstation (DIWS). Use of OPEN LAN ACCESS 7 is defined innetwork generation.

1.7 GXTI

GXTI is a programmatic interface which allows a GCOS 7 application to access aremote application through ISO transport, TCP or UDP transport, or RFC1006transport.

It supplies a unique communication interface:

• with remote applications through the ISO transport located in the OCS FrontEnd,

• with remote ISO/DIWS applications through the RFC1006 transport located inthe OCS front ends (without programmatic interface modification),

• with remote applications through the ISO transport located in a Datanet viaFEPS,

• 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 frontends,

• with remote applications through the TCP or UDP transport located in theOPEN7 subsystem. Note that access to TCP/UDP from FCP7 and OPEN7 aremutually exclusive in the sense that one cannot establish connections from TCPto OPEN7 and to FCP7, but both can be launched simultaneously. In such acase, FCP7 has priority. If the GXTID daemon under OPEN7 is launched beforeFCP7, FCP7 stops GXTID to force the connections to pass via FCP7. If FCP7 islaunched before OPEN7 (and therefore before GXTID), FCP7 has priority.

Introduction

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1.8 RFC1006

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

1.9 TCP/IP

TCP/IP allows GCOS 7 applications to reach remote applications on a UNIX orTCP/IP station. TCP/IP is available in the OCS front ends for applications usingthe 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 forGCOS 7 applications.

1.10 Network Configuration

Under GCOS 7, the generation utility used for the network configurations isNETGEN (NETwork GENerator). NETGEN is described in the manual NetworkGeneration.

An OCS Front End is configured each time its OCS server is started (STSVRcommand). This configuration loads the parameters necessary for thecommunication protocols handled by the OCS Front End. The OCS Front Endconfiguration is described in the manual Network Generation.

The Datanet and the CNP7 need to be configured through their own configurationtools. These tools are described in the Datanet or CNP7 manuals.

Network configurations directives for DPS 7000 and its FEPs are staticallygenerated by their respective configurators from descriptive information entered bythe network (or system) administrator.

The following terminology is adopted throughout the documents:

DIRECTIVE any statement appearing in a network configurationdescription which can be processed by a networkconfigurator.


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1.11 Network Administration

Network administration allows a network (or system) operator to handle localfunctions such as starting or terminating the servers, to survey the behavior of thenetwork and to modify dynamically network attributes through networkadministration 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.

47 A4 92UC Rev02 2-1

2. ISO/DSA and ISO Communications

The OSI reference model of ISO defines a basic software architecture ofcommunications, based on layered functions.

DSA defines a layered architecture which complies with the OSI reference modelof ISO. This means that the concept of a layered architecture and the role of eachlayer are common to DSA and ISO. Depending on each layer, GCOS 7implements either the ISO standard for the layer or a proprietary Bull DSAstandard.


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2.1 Concepts of a Layered Architecture

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

Layers Application

Presentation

Session

Transport

Network

Data Link

Physical

7

6

5

4

3

2

1

<-protocol->

<-protocol->

<-protocol->

<-protocol->

<-protocol->

<-protocol->

<-protocol->

Physical Media

System A System B

service

7

6

5

4

3

2

1

service

Figure 2-1. DSA/ISO Layers

Except for the highest or lowest layers, each (N)-layer provides the (N+1)-layerwith 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 peerin another system. The set of rules governing this co-operation is termed protocoland is associated with the layer for which it is implemented. The data exchangedwhen implementing the protocol of the concerned layer is its PDU (Protocol DataUnit).

Such architecture ensures that each layer and also application is independent of allsubsequent subsystems implementing the lower ISO layers. For GCOS 7, thelayers 1 to 5 protocols and services fully comply with ISO standards as well as theDSA standard.

ISO/DSA and ISO Communications

47 A4 92UC Rev02 2-3

2.2 ISO and ISO/DSA Layers Implementation

GCOS7

VCAM

TNS

Datanet

PSI

CNP7

ISL

Appl/Pres

Session

Transport

Network

Link/Physical

TDS UFT FTAM

OCS

FCP7

ISL Controller

FDDI SAS

Ethernet

X400

LAN Extender

Line Modules

WAN Processor

MainWay 2000

FEPSpseudo-transport

IOF

Figure 2-2. DSA/ISO Layer Implementation on DPS 7 running in BullDecor

Modules shaded / / / concern the front-end processors, not GCOS 7.


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TDSIOFUFT

VCAM

OCS

VCP7

DRIVER

NETWORKADAPTER

Mainway 2000

Application/Presentation

Session

Transport

Network

Link/Physical

Figure 2-3. DSA/ISO Layer Implementation on DPS 7000 running incommodity Decor


47 A4 92UC Rev02 2-5

Application Layer

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

The primary network consists of ISO/DSA applications which communicate witheach 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 whichfunctions 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 terminalmanager and the terminals (secondary network) does not comply with theISO/DSA standard. For example Mainway 2000 as session endpoint provides thesupport of Terminal manager for accessing terminals.

Presentation Layer

The Presentation layer (6) is concerned with the conversions and formatting to beapplied to the contents of data exchanged between applications.

Presentation functions are often embedded in system software or firmware such asASCII-to-EBCDIC conversion. They can also apply to specific products such asFORMS for handling the display of information on the terminal screen.

Session Layer

The Session layer (5) organizes and synchronizes the dialog between twoapplications. It establishes connections, manages the flow of data exchanged, andcontrols the turn (token) among session endpoints.

A session connection can be established by the session layer between twoapplications 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 andmessage exchange between the applications pass through VCAM. However, whenapplications reside in different systems, the session layer uses the transport servicesto exchange messages between the systems.

Depending on the application, VCAM implements the ISO or DSA protocols andservices of the session layer. One part of VCAM implements the ISO sessionprotocol and services while another part implements the DSA session protocol andservices.


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VCAM-DSA provides the interface for DSA applications such as TDS, IOF andUFT, 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 ISOsession to a DSA session in order for a DSA remote application working over anISO session (such as OPENTEAM, UFTX ... ) to dialog with a GCOS 7 DSAapplication (TDS, IOF, UFT ...).

In addition to this protocol conversion, OPEN LAN ACCESS 7 provides anaddressing conversion from ISO to DSA.

Transport Layer

The Transport layer (4) assures a reliable transport for transferring data betweensessions of different systems. Transport services control sequencing and flow ofdata, detect errors and provide recovery.

Depending on the network configuration, a session connection maps onto either asingle end-to-end transport connection or a sequence of transport connectionsrelayed consecutively.

In the case of a connection thru OCS, the ISO class 4 protocol (ISO IS 8073) isimplemented in the OCS Front End itself. Therefore ISO/DSA and ISO transportconnections can be established with remote systems directly connected to the OCSFront End.

In the case of a PSI connection to the Datanet, the transport layer is spread betweenFEPS and the Datanet. FEPS implements a pseudo-transport which is limited onlyto exchanges with the Datanet. The transport layer and all layers below it areimplemented in the Datanet. It is the Datanet and not the DPS 7000, which isresponsible for implementing the transport and network protocols in acommunication with a remote system.

In the case of an ISL connection, TNS implements the ISO class 4 transportprotocol (ISO IS 8073). DSA and ISO/DSA transport connections (known as"DIWS" transport connections) can therefore be established with remote systemsdirectly connected on the ISL. In the case of ISO transport connections, it isnecessary to establish these connections through the ISO transport of a CNP7 (orDatanet) connected on the ISL.


47 A4 92UC Rev02 2-7

The ISL can connect the FEP (CNP7 or Datanet) which functions as a relay inestablishing the session between the DPS 7000 and a remote system. One transportconnection ends in the FEP, while another transport connection is initiated betweenthe FEP and the remote system. These two transport connections are directlylinked (back-to-back transport). The transport connection between the FEP and theremote system may use a protocol different from that of ISO class 4 between theDPS 7000 and the FEP. This allows accessing systems which implement anycombination of transport and network protocols supported by the FEP, on any kindof ISO network.

Figure 2-4 shows a DPX/20 connected to a DPS 7000 via its CNP7.

· · ·

DPS 7000

CNP 7

DPX/20

ISL

X25 X25

HDLC HDLC

null network null network

ISO transport ISO transport

ISO session ISO session

ISO transport ISO transport

IEEE 802.2IEEE 802.3

IEEE 802.2IEEE 802.3

Figure 2-4. ISO Transport Connection

RFC1006 Transport Layer

The RFC1006 transport layer is available only via OCS. It implements a class 0transport protocol improved to run on top of TCP (which can be assimilated to aclass 4 transport protocol). It uses elements of the procedure and the TPDU formatdefined in ISO IS 8073.

Figure 2-4 shows DSA applications communicating via RFC1006.


2-8 47 A4 92UC Rev02

DSA Application

DSA Presentation

DSA Session

RFC1006

TCP

IP

Link

Physical

Bull DPS 7000

DSA Application

DSA Presentation

DSA Session

RFC1006

TCP

IP

Link

Physical

Other System

IPS Network

Figure 2-5. DSA Applications Communicating via the RFC1006 Transport

RFC1006 supports communications between DSA applications (shown in thefigure), 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. Networkservices route the link through available intermediate systems, relay theinformation through the established link, and maintain the link for the duration ofthe user session.

Figure 2-6 represents a typical network configuration with a relay system Cinterposed between Systems A and B, involving the network and lower layers.

In ISO/DSA networks, such a relay system is usually a communications controlleror FEP. In the case of an ISL connection, TNS implements a basic network layerreferred to as the null subset of Internet (ISO IS 8473) which is also called inactivenetwork. In the case of a connection via the OCS Front End. OCS Front Endimplements 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 Networklayer located in the FEP can be an inactive network, the full Internet protocol orother network protocol such as X25 (ISO 8348).


47 A4 92UC Rev02 2-9

7

6

5

4

3

2

3

2

A B

C

1 1

Media Media

7

6

5

4

3

2

1

Figure 2-6. DSA/ISO Communications Controller

Data Link Layer

The Data Link layer (2) provides a point-to-point transfer of individual frames ofdata over a physical connection.

In the special case of a LAN (ISL or OCS), this layer is composed of the twofollowing sublayers:

1. LLC (Logical Link Control) sub-layer which has a logical addressingcapability

2. MAC (Media Access Control) sub-layer which interfaces with the physicallayer by means of physical addressing.

Physical Layer

The Physical layer (1) provides a mechanical, electrical, functional and proceduralmeans to transmit bits.

The ISL Ethernet controllers implement the link and physical layers (ISO IS8802.2, 8802.3). The FCP7 FDDI controller implements the link and physicallayers (ISO IS 8802.2, 9314).


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2.3 DSA Addressing

A DSA application address is composed of the address of the session control towhich 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 theSCID:

• A unique TSAP identifier for each session control entity within the networkidentifies it as a user of transport services. Both source and destination TSAPidentifiers are only used by the ISO transport entity as part of the transportconnection 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 defaultdeclared by the TPROTOCOL=ISO[:1] parameter of the RTS directive.

• The SCID which gives the address of the DSA session control used by theDSA200 session protocol to identify the session control in the session protocoldata 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 communicationsapplication can be addressed through several mailboxes, each mailboxcorresponding to a specific entity within the application. In TDS, for example, themaster operator is addressed through a mailbox different from that dedicated toother users. Similarly, the Terminal Manager addresses a specific terminal by aunique address given by its mailbox:mailbox-extension.

Lower layer entities also have addresses configured at Network Generation. In thecase of communications through an FEP, such entities are not located within theDPS 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 remotesystem, additional addresses have to be considered.

Dedicated LSAP (Link Service Access Point) addresses are used at Link level toseparate the different kinds of traffic over the interface between TNS and the LocalNetwork Adaptor. The LSAP is used by the ISL controller to choose a type ofLogical Channel, also known as Logical Terminator (LT), for an incoming framewhich must be directed to TNS.


47 A4 92UC Rev02 2-11

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 andDUMP) using a specific administrative protocol

• TCPIP for the TCP/IP module of GCOS 7 (OPEN 7) which uses the directaccess in the Link-layer of TNS.

A transport connection request is sent over a Network Route configured on theLocal System which is seen as the source of the route going from the LPL (LocalPhysical 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 of48 bits and must therefore be declared in the network configuration.

Up to 8 MADDRs (Multicast Address) can be shared among different LPLs. Theseaddresses are used to receive some specific broadcast messages over the cable foradministration purposes.

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

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

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


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Example of Address Configuration

The example below illustrates two systems DPSA and DPSZ, each connected to itsown CNP7 through an ISL cable, the CNP7s being interconnected to participate ina WAN (wide area network).

DPS 7000

86:57

CNP 7 DPS 7000CNP 7

"CNPY" "DPSZ"

86:23

LCT RCT RCT LCT

CABLE-1 CABLE-2

ISLs

WAN"DPSA" "CNPB"

5E-00-01LPL_DPSA

5F-00-01RPL_CNPB

5F-00-02RPL_CNPY

5E-00-0CLPL_DPSZ

Figure 2-7. DSA/ISO Address Configuration

Before application LAPPL running on the system DPSA can dialog withapplication RAPPL running on the system DPSZ, it must first establish aconnection.

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. Therespective Session Controls of DPSA and DPSZ, LSC and RSC, are unique andnetwork-wide to identify the addresses of LAPPL and RAPPL unambiguously.


47 A4 92UC Rev02 2-13

2.4 OSI Addressing Concepts

The network addressing follows the same conceptual principles as addressing aletter or dialling a phone number. In both cases, the targeted destination isaccessed only if the addressing is unambiguous.

An application, running on the local system, requests the local communicationservices to establish a connection with a desired correspondent located in a remotesystem and identified by an address. Each system in a chain of systems throughwhich the connection transits, routes this request by forwarding it to the nextsystem along the chain until the destination is reached. Any configuration error inthe sequence may prevent the correspondent from being accessed.

The OSI communication architecture being represented by the 7 layers OSI stack inwhich each layer can be accessed by a specific address, shows that the OSIaddressing 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) ofOSI 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 byaccessing 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)-entitiesin a given system. Selectors are the addressing information that are exchangedbetween systems. They are allocated by a system and are unique within the scopeof this system.


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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 ofa 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 addressedby an address of PSAP (Presentation Service Access Point) which has the structureshown in Figure 2-7.

NSAP (Network Service Access Point)

PSAPAddress

<- addresses in hierarchical order ->

PSEL (Presentation selector)

SSEL (Session Selector)

TSEL (Transport Selector)

SSAPAddress

TSAPAddress

Figure 2-8. OSI PSAP Address Structure


47 A4 92UC Rev02 2-15

2.4.2 Network Layer Addressing: NSAP Address

For further information on the topic treated in this paragraph, refer to the documentISO8348/Addendum 2.

For outgoing connections, the local system will use the list of NSAPs to determinethe correct Network layer, within the set of these NSAPs. A NSAP addressidentifies one Network Service Access Point within an End System at which theNetwork 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 forallocating the values of the IDI,

− the abstract syntax of the DSP (Domain Specific Part) such as being in binaryor decimal.

Figure 2-10 summarizes the allocated AFI values by authority and DSP syntax.


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DSP SyntaxAuthoritydecimal binary

X121 CCITT

ISO DCC

F69 TELEX

E163 RTC

E164 RNIS

ISO ICD

LOCAL

36,52

38

40,54

42,56

44,58

46

48

37,53

39

41,55

43,57

45,59

47

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 thatdomain.

The DSP (Domain Specific Part) represents a private addressing part and can beencoded in binary or decimal. Its semantics is determined by the authorityidentified by the IDI. It can contain TRANSPAC or ETHERNET addresses.


47 A4 92UC Rev02 2-17

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

DSP SyntaxAuthoritydecimal binary

X121 CCITT

ISO DCC

F69 TELEX

E163 RTC

E164 RNIS

ISO ICD

LOCAL

36,52

38

40,54

42,56

44,58

46

48

37,53

39

41,55

43,57

45,59

47

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❑


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ECMA 117 Recommendation

The DSP field is split up into 4 successive fields:

• organization identification which is specified if the authority is DCC or isomitted if not,

• subnetwork identification,

• address in the subnetwork,

• network selector (NSEL).

Figure 2-12 gives the maximum length for each field depending on the DSPabstract syntax specified by the AFI:

type

decimal

binary

(6 digits )

(2 bytes )

5 digits

2 bytes 6 bytes 1 byte

15 digits 3 digits

NSELsubnetworkaddress

Organizationidentifier

subnetworkidentifier

Figure 2-12. Field Lengths in OSI NSAP Address

EXAMPLE (ECMA 117 Recommendation):

The ECMA 117 address 3925025643200FE02608C5A2BC01F can be brokendown 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)❑


47 A4 92UC Rev02 2-19

A network entity may need to support more than one NSAP because of thefollowing:

1. The system may support one NSAP address for each directly connectedsubnetwork.

2. Some applications, with no T-selector or S-selector are addressed directly bythe NSAP, each needing a specific NSAP.

3. Several authorities may administer the site and so allocate different NSAPformats.

Special NSAP Format for RFC1006

A special NSAP address format has been defined for use when OSI applications arerun over networks that do not provide the OSI Network service. This formatcovers TCP/IP networks supporting COTS using RFC1006.

The Telex AFI with DSP decimal encoding is used. The Telex number in the IDIplus the Prefix field of the DSP identify a particular network. The remainder of theDSP 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).


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

54 00 72 87 22

prefix IP address port padding

03 12 91 83 00 10 84 00 10 2 0

DSP

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 scopeof the End System to which it is allocated. A transport selector is used to identifyone and only one session entity within the End System. The term Session Entityimplies not only the OSI communications layer which implements the OSI sessionprotocol but also applications directly using a Transport Programmatic Interface.

Transport Selectors are allocated independently for each End System since noglobal authority is required for this allocation.

Transport Selector values are directly encoded as TSAP-id parameters of TransportConnection Request and Confirm Data Units.

The TSEL, suffixed by the NSAP address, becomes an address of TSAP. BothTSEL and NSAP are used by the Front-End processor to choose the host for anincoming connection using a UT (User of Transport) object.


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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 Connectand 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 theConnect 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 OSIlayers:

• Remote PSAP to identify its correspondent,

• Local PSAP to identify itself.

In later releases, directory services will help applications get the PSAP addresscorresponding to a given AET.


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2.4.7 Default Local Addresses

When calling communications services, the local application must supply bothlocal and remote PSAPs to identify itself and its remote correspondent. Both localTSEL and local NSAP are optional.

If the local TSEL is absent, it is set by the session layer to the default local TSELimplicitly configured. The local NSAP is set by the Frontend processor, dependingon the network attachment chosen. If an application does give a local NSAP, it isconsidered a reconnection, and the Frontend processor will then use the localnetwork 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 thehost itself but not in the Frontend processor.

In the case where the DPS 7000 connects directly to another DPS 7000 over theISL, the first NSAP defined for the LSYS is taken into account.


47 A4 92UC Rev02 2-23

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 ISOstack and to benefit from all ISO sublayer services, a mechanism has beenimplemented in GCOS 7. This mechanism is an on-line and transparent modulewhich converts the DSA session to an ISO session by migrating from DSAaddressing to OSI addressing. These PID (Prise ISO-DSA, French for ISO-DSAPlug) modules are invoked depending on the information given on addressing andconfiguration:

• at connection time,

• and when needed during data transfers.

Migration Goals

The Bull DSA proprietary communication architecture is not so far removed fromOSI communications architecture. However, DSA addressing which involvessession address and application mailbox, differs considerably from OSIhierarchical addressing.

To be compatible, migration is necessary from non-hierarchical (flat) DSAaddressing to OSI addressing.

Addressing migration is performed by the PIDa, the addressing PID which is themodule interfacing the session with the transport layer at each inward or outwardconnection requests.

The advantages of such a mechanism are:

• Any site having a mix of OSI applications such as X400 and FTAM, and DSAapplications will use only one communications stack and one networkconfiguration to communicate between both sets of environments.

Without such a mechanism, two completely separate network architectureshave to coexist, thereby increasing the overheads of communicationsmanagement with the increase in the development and use of OSIapplications.


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• Foreign systems can connect to Bull proprietary applications whose layers 1through 5 fully conform with the OSI stack. This means that such systems donot have to undergo regeneration and reconfiguration to comply with Bullnetworking standards.

• Connections between GCOS 7 and DIWS (DSA-ISO Workstation) over the ISLare direct.

The function of the PID in the DPS 7000 can be shown as follows:

ISOapplication DSA application

DSA sessionISOsession

iso addressingand iso protocol

dsa addressiso protocol

otherapplication

othersessionorGXTI

dsa addressdsa protocol

PID

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 conversionfrom DSA session protocol, used by DSA applications on the DPS 7000, to ISOsession protocol.

This protocol conversion follows Bull SID (specifications ISO-DSA) standardswhich 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 (doubleconversion).

When activated for a given session connection, this module transforms incomingISO SPDU (Session Protocol Data Units), into DSA letters before handing themover to VCAM.

Similarly, outgoing DSA letters are transformed into ISO SPDUs.


47 A4 92UC Rev02 2-25

2.5.3 Address Conversion Mechanism

• For both Local (L) and Remote (R) systems involved in the connection, theaddress conversion performed by the PIDa consists of:

LMBX [EXT], LSCname <- translated into -> LSSEL, LTSAPRMBX [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 directoryconfigurations.

TSAP = TSEL + NSAP list

• TSEL is used to select a session layer service among those provided by theDPS 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 notexplicitly declared in the network configuration, the default PID-TSEL internallysupplied is:

"PID_SELECT" in ASCII coding: "5049445F53454C454354"X


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ISOapplications

DSAapplications

DSA session

ISOsession

TSELx

otherapplications

orother session

PID

TSELz PID_TSELTSELy

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

• Two systems may have the same TSEL where, for example, both have thePID_TSEL default value. The NSAP is used to select the FEP which accessesthe TSEL. Each NSAP must be unique in the network configuration. Forfurther details on OSI addressing, see Paragraph 2.4.

If the FEP gives access to 2 different systems which have the same TSEL, theremust be at least 2 different NSAPs to select the host:

NSAP1 NSAP2

PIDvalue

TSELdefault

PIDvalue

TSELdefault

HOST 1 HOST 2

FRONTEND

Figure 2-16. Two Systems with the Same TSEL


47 A4 92UC Rev02 2-27

NSAP

PIDvalue

TSEL1

PIDvalue

HOST 1 HOST 2

FRONT END

TSEL2

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/ISOWorkstation on the ISL:

S7-1 X1

DPS 7000

ISL

DSA/ISO Workstation

Figure 2-18. PIDp Generation Example

The source generation to perform the network configuration of the DPS 7000 S7_1is:

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 PIDpmodule. The DSA address is determined from SCID. For more details on networkconfiguration, see the manual Network Generation.


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Below is an example with protocol and address conversion:

NSAP=04

NSAP=02

S7-1

PID=0102

DN1

NSAP=05

DN2

NSAP=01

NSAP=06

NSAP=03

S7-2

PID=0203

ISL

X1

X2

X3

Figure 2-19. PIDa Generation Example

The source generation to perform the network configuration of S7_1 of ISOaddress 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=ISOretrieves the PID TSEL with its default value PID_SELECT. The DSA address isdetermined from SCID. These parameters, explicitly declared or configured bydefault, will be dynamically retrieved by the communications routing services,namely the PIDa module. For more details on network configuration, see themanual Network Generation.


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2.6 Use of TNS Extension for ISO Sessions

For an outgoing ISO connection from the DPS 7000 host to a remote systemthrough 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 FEPthen chooses one NSAP among several, depending on the network used to accessthe remote system.

The calling TSAP, the called TSAP and the Quality-of-Service parameters areexchanged between TNS and the FEP software in an extension of the CR TPDU oftransport protocol.

The connection between TNS and the FEP is seen as a channel connectionproviding the session-to-transport interface from the host to the FEP.

This transport protocol extension is declared at NETGEN by the ISO:2 parameterof 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.


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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 usesthe Session Routing module to select a Session Route.

When necessary, the OPEN LAN ACCESS module (PIDp or PIDa) is called inorder 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 itsassociated servers.

A Session Route can be explicitly defined at Network Generation to manage itsstate (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 areestablished 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 outwardconnections over all the available routes. This load balancing takes in account thenumber of outward and inward connections already established through the sessionroute.


47 A4 92UC Rev02 2-31

With Quotas Defined

The session routing function will try to balance, for a given remote system, theoutward connections depending on the quotas defined for the routes to this remotesystem and depending on the connection already established. If one or severalsession route are defined with quota equal to zero, they will be considered asbackup routes.

Notes:

The algorithm function of the RSC address is always used when the routes are ofthe same "weight" (either all quotas are one, or quotas are different from zero).

When a connection attempt fails, the session routing function automatically retriestowards 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 reusedonly if all other routes are unavailable or if new inwards connections have beenestablished 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 theremote 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 asbackup.

• 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 RTSor to use default quotas (quota=1).

TNS will try to balance the connections over all the available RTSs dependingon the inward connections already established and on the value of quotas.


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2.9.1.3 Inward Connection Mechanism

Inward connections from a remote system are accepted by VCAM only if theentering server is defined in the list of servers for this system.

When connections enter via TNS, the connection is accepted only if the enteringRTS is defined in the list of RTS of this system.

When necessary, the OPEN LAN ACCESS module (PIDp or PIDa) is called inorder 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 invokedby the session layer.

This session routing module is in charge of choosing a transport layer server, eitherTNS, OCS or an FEPS occurrence, with the appropriate FEP (frontend processor).

The choice is made using the given remote TSAP address and the information inthe 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 addressgiven in the destination address, and returns the server reference to VCAM,

• when a connection request towards either TNS, OCS or an FEPS occurrencefails, VCAM calls on the session routing service to find another available server;this process continues until a new server is found and VCAM retries theconnection request towards this new server,


47 A4 92UC Rev02 2-33

• when all attempts using the first NSAP fails, the next NSAP in succession isused,

• an internal mechanism is implemented to avoid infinite looping during theseretries,

• if no route is available to establish an outward connection towards any of theFEPs, using all the NSAPs in the list, the connection will fail.

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

Subdomains

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

• if no subdomain is declared in the directory configuration, all the started serversand available FEPs are used,

• if subdomain objects are declared, valid servers are restricted to those able toaccess the passthroughs or neighbors declared in the SUBDOMAIN directives,

• choosing a subdomain from a given NSAP uses a best-matching algorithmbetween this NSAP and all the declared NSAP prefixes; each prefix identifies asubdomain and the largest size which matches, is the best match which selectsthe subdomain.

The SUBDOMAIN directive is mandatory in accessing a system directly connectedto 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 thephysical address of the system on ISL (described in the basic networkconfiguration and known to TNS).


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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 theapplication in the QOS parameters,

• with the offered quality of service configured in the generation by means of theSUBDOMAIN object.

The requested desired and minimum class are taken into account as follows:

Maximum

Minimum

refused refusedresult of connectionrequest

Quality of Service Offered

case 1 case 2 case 3 case 4

Requested Quality of Service(desired and minimum)

Q desiredQ minimum

Q minimum Q desired

Q desired

acceptedaccepted2nd choice

(Q minimum)

Figure 2-20. ISO Quality of Service

Output network ways may be divided into classes which can be dispatched over thepossible passthroughs.

Examples of criteria affecting classes are:

• communication costs,

• level of throughput,

• and types of subnetwork.


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2.9.2.3 Inward Connection Mechanism

The ISO session layer is warned of an incoming connection request by the arrivalof a CONNECT SPDU from the transport layer.

The called address is then computed by the session layer to identify a VCAM-ISOSSAP 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 thelocal 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 applicationconcerned.

2.9.3 FEPS Pseudo-Transport

2.9.3.1 Inward Connections

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

• on the DPS 7000 side, the FEPS occurrence manages the communicationscontroller which links the Datanet by its PSI channel,

• on the Datanet side, DNS establishes the transport connection between its localtransport layer and the remote transport.

The management of the exchange interface by FEPS and DNS follows asymmetrical pseudo-transport protocol, which is only in charge of ensuring thetransport-session interface between the DPS 7000 and the Datanet.

Since the data transfer over the PSI is highly reliable, pseudo-transport protocol isonly concerned with:

• connection and disconnection requests,

• acknowledgement,

• full duplex data transfer.


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When FEPS receives a transport connection request from VCAM, it receives thecalling and called TSAP and QOS, the called TSAP possibly being provided withseveral NSAPs.

All these parameters are sent to DNS which establishes an end-to-end transportconnection towards the ISO network, using TSAPs and ISO routing services. Forfurther 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-transportconnection with addressing and QOS information is sent to FEPS. See AL objectin the DNS-V4 documentation.

Pseudo-Transport and Upper Layer Selection

When FEPS receives an inward connection request, it operates like TNS inretrieving the upper layer. The software module used is the same in bothconnection cases.


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2.9.4 TNS Connections


Transport Layer

TNS acts as a full transport layer on ISL network by using network informationlocated 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 itsconfigured 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 involvessearching the configuration tables for a valid network route to access the remotetransport layer.

In connectionless mode, a valid network route is one which is eligible to proceedfrom 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 directlysent over the network

• if the RPL does not acknowledge the request, it is assumed that either thenetwork 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 thenumber of retries over all the configured networks, is exhausted.


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Frame Transmission

When several ISL network attachments are simultaneously available, TNS choosesthe one with the lowest activity and is able to switch to another network as soon asthe current chosen one fails.

A frame is set up with the physical ETHERNET address parameters of both thelocal and remote systems and the LSAP binary values of 20 (ISO LSAP). Once setup, the frame is conveyed in a channel program which transmits it to the localnetwork board to be send over the ISL cable. The addressed remote entity will thenreceive the frame.


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 destinationETHERNET address of the frame. If it matches either its own address or any of itsconfigured 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 (bydefault: from 080038100000 through 0800387FFFFF), the frame is dispatched bythe controller over each configured logical I/O link called the LT (LogicalTerminator) 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 areinternally 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.


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

• if the LT is specified with LSAP=RM, the frame is processed by the remoteadministration module of TNS,

• if the LT is specified with LSAP=ISO, the frame is dispatched to the networklayer,

• if the LT is specified with LSAP=TCPIP, the frame is dispatched to TCPIPmodule.

Network Layer

The received frame is analyzed according to its network header.

If its header is ISO8473 null subset (standard network protocol), the sourceETHERNET address is checked among all those configured for identifying thesender:

• if the configured address is found, the TPDU is extracted and sent to thetransport layer,

• otherwise the frame is discarded.

Transport Layer

On receiving the TPDU from the network layer, the transport layer processes itaccording 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 toprocess it for an already existing connection.

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


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Selecting the Upper Layer

Selecting the upper layer depends on the TSEL. Each entity of the upper layer iscalled to check which one owns the given TSEL.

The addressing PID module, as in outward connection mechanism, is also calledupon to assume compatibility with DSA-session connections, and addressconversion from ISO to DSA.

2.9.5 OCS Connections


Transport Layer

OCS Front End acts as a full ISO transport layer by using network informationlocated in the OCS Front End configuration description.

When OCS Front End receives a transport connection request from VCAM itreceives:

• TSAP addresses (calling and called),

• connection parameters,

From its configuration description it searches the passthrough system to use andattempts a transport connection towards this passthrough, using all its configuredinformation:

• its physical address,

• specific parameter values for transport,

Network Layer

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

Frame Transmission

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


47 A4 92UC Rev02 2-41


Frame Reception

Once the OCS server has started, the OCS Front End (with its associated Adaptercard) “ listens ” the network. The destination address of the entering frame allows afirst 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 theNSAP is not valid, the frame is discarded.

Transport Layer

On receiving the TPDU from the network layer, the transport layer processes itaccording 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 toprocess it for an already existing connection.

Selecting the Upper Layer

Selecting the upper layer depends on the TSEL. Each entity of the upper layer iscalled to check which one owns the given TSEL.

The addressing PID module, as in outward connection mechanism, is also calledupon to assume compatibility with DSA-session connections, and addressconversion from ISO to DSA.


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2.10 Direct Interfaces to Communication Layer

2.10.1 Transport Interface

The GXTI module implements a fully compatible interface with X/OPEN XTIspecifications 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 andV2 session services as described in ISO standards.

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3. TCP/IP Communications

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

3.1 TCP/IP Layered Architecture

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

Link

Application

Session

Transport

Network

Physical

SMTP

IP

Link

FTP Telnet XTI NFS SNMP

Presentation

TCP UDP

Physical

X25Network

Ethernet TokenRing

FDDI

ICMP

Figure 3-1. TCP/IP Layered Architecture


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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 inthis 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 supportsclient/server architecture. An NFS client accesses files, an NFS server providesfiles for access.

RPC (Remote Procedure Call) part of NFS allows to call remote procedures as ifthey were local.

Telnet (TErminaL NETwork) enables terminals to access remote systems.

SNMP (Simple Network Management Protocol) is a network administrationfacility.

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 maximumdatagram size, breaks up messages into datagrams (for sending), re-assemblesdatagrams into messages (after receiving), re-transmitting "lost" datagrams, and re-sequencing datagrams (which arrive in the wrong order). It is suitable where areliable communication of messages is needed.

UDP is a connectionless transport mode. It is used for messages which fit into asingle datagram and which can be re-sent if not acknowledged. It does notguarantee the order of arrival. It does not guarantee arrival at all.

ICMP is a administrative protocol. It managers PING messages.

TCP/IP Communications

47 A4 92UC Rev02 3-3

Network Layer

IP (Internet Protocol) is equivalent to the OSI network layer.

IP receives datagrams from TCP, ICMP and UDP. Each datagram has a specifieddestination. IP is responsible for routing individual datagrams, and consequently itmust know the network configuration. IP does not know how datagrams relate toone another and is not concerned with the structure of the message (if this is largerthan 1 datagram).

IP keeps track of all the routes and handles incompatibilities between differenttransport media. If IP cannot deliver a datagram within a reasonable time ("time tolive"), it discards the datagram. If TCP is used at the transport layer, then TCPmust arrange for the re-transmission of "lost" datagrams. If UDP is used at thetransport 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 synchronousconnection 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 CollisionDetection), Token Bus, Token Ring, and FDDI (Fiber Distributed Data Interface)for LANs.


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3.2 TCP/IP Addressing Concepts

3.2.1 IP Addresses

Figure 3-2 shows the format of IP addresses.

Class A

Class C

Class B0 Network Local

14 bits 16 bits

0 Network Local

7 bits 24 bits

1

0 Network Local

8 bits21 bits

1 1

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.


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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 tobe class A). The next 7 bits are the network number.The last 24 bits are the local address. Class is used ifthere are few networks and many hosts (on thenetworks).

Class B The high order bits are 10 (which defines this addressto be class B). The next 14 bits are the networknumber. The last 16 bits are the local address. Class isused if there are many networks and many hosts (onthe networks).

Class C The high order bits are 110 (which defines this addressto be class C). The next 21 bits are the networknumber. The last 8 bits are the local address. Class isused if there are many networks and few hosts (on thenetworks).

IP addresses are usually shown in "dot notation". In dot notation, the IP address isshown as a string of up to 4 decimal numbers. Each decimal number must be lessthan or equal to 255. A dot (.) is used to separate the decimal numbers. Eachdecimal number is interpreted as a 1 byte hexadecimal number. Each byte isassigned to the IP address (in the format shown in Figure 3-2) from left to right. Iffewer 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.


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3.2.2 MAC Addresses

A MAC address is a string of 12 hexadecimal digits arranged in pairs. The pairsare separated from each other by a colon (:) character. Blanks are not allowed in aMAC 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. TheARP protocol can automatically load this table.

In the case of OCS Front End, for a remote TCP/IP station, the association betweenits IP address and its MAC address can be done using ARP commands in the IPSconfiguration (see the manual Network Generation).


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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.

GXTI

Applications

OCS

FDDI

FCP7

GCOS 7

FCP7 FCP7 FCP7

FDDIFDDIFDDI

IPLayers 1/2

TCP UDPICMP

IPLayers 1/2

TCP UDPICMP

IPLayers 1/2

TCP UDPICMP

IPLayers 1/2

TCP UDPICMP

Figure 3-3. TCP/IP via FCP7

A DPS 7000 can be connected to FDDI networks. Up to 4 FCP7 integratedcontrollers can be installed, and each FCP7 can be connected to a different FDDInetwork (as shown in the figure).

In the GCOS 7 NETGEN, each FCP7 must be declared via an LCT directive, andeach OCS server occurrence via an SVR directive. An LT is implicitly generatedfor IPS in each FCP7.


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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 FCP7configured 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 IPSstack configuration. The user configures each of the IPS FCP7s. OCSautomatically "adds" the individual configurations to produce the Multi-IPSconfiguration. If an IPS FCP7 configuration is subsequently modified, OCSautomatically applies the modifications to the Multi-IPS configuration.

At Application level, Multi-IPS gives the same visibility (as far as is possible) as aMulti-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 IPSFCP7. In this context, bind means the association of a local address with thetransport end-point.

• A previous "ANY" bind is automatically applied to each IPS FCP7 which startssubsequently if its port number is free. If the port number is not free, the bindis not applied.

• A new incoming UDP dialog is responded to by the "incoming" IPS FCP7 (thatis, the one which received the request).

• For a new outward UDP dialog or TCP connection, the IPS FCP7 chosen is theone which has the most precise description of the IP address (or mask) of theremote site (or network) in its IPS stack configuration.

• If an attempt to make a TCP connection fails (that is, a failure at connectiontime), then Multi-IPS automatically retries on another IPS FCP7 (as in the caseof 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).


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3.3.2 TCP/IP via OPEN7

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

Files

FDDI Driver ISL Driver

IP

XTIdaemon

Applications

TCP

TDS

NFS FTP Telnet

FCP7

Ethernet

ISL

ISL Controller

GCOS 7

IOF ORACLE GXTI

Affinity XFORMSSQL*NetRelay

Layers 1/2

FDDI

Figure 3-4. TCP/IP Access via OPEN7


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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 orthe 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 specificTCP/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 FCP7is still managed administratively by OCS, but the OPEN7 FDDI driver accesseslayers 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 implicitlygenerated Logical Terminator (LT).

For IPS frames, a second level of filtering is done on the IP address. If the IPaddress corresponds to that of OPEN7, the frame is transmitted to OPEN7. Allother frames are transmitted to the IPS stack of the FCP7.


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3.3.3 TCP/IP via INTEROP7 on commodity Decor

In the case of a DPS 7000 running in a commodity Decor, TCP/IP communicationscan be performed thru the commodity TCP/IP software associated with this Decor.Then access are made directly from GCOS7 thru basic services allowing tocommunicate with the TCP/IP modules. Services are provided also at the level ofthe Extended Virtual Machine, or at the level of the commodity code itself to useTCP/IP protocols for access to applications or data bases from the Open world.

GCOS7 services or applications can communicate thru TCP/IP, using Socketservices (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 forexample:

• Oracle with SQL*Net use on the network• Java, with Corba use on the network

See Figure 3-5, TCP/IP via INTEROP7 on commodity decor.


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DPS 7000

Commoditysoftware

SOCKG7

RPC

GCOS 7 Applications and Services usingTCP/IP telecommunications

GCOS 7

Open worldservices

Commodityservices

TCP/IP + Driver

Extended virtual machine

WINSOCK

n LAN Adapters

Figure 3-5. TCP/IP via INTEROP7 on commodity decor

47 A4 92UC Rev02 4-1

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 ofthe network, each with its own generation description to describe its own localview of the network.

The most basic network is made out of a DPS 7000 and its direct connections to aLAN (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 hostsystems interconnected thru LAN’s and WAN’s (public Wide Area Networks forexample)

GCOS7 network generation tool is NETGEN.

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

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

This section describes NETGEN and OCS configurations.


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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 ismade, 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 basicnetwork configuration are statically configured; that is, when this configuration isenabled:

• they are immediately available to the communications servers at connectionrequest time

• they remain available during all the communications session

• they cannot be deleted, added or modified during the communications sessionwhich has enabled them.

Directory of Remote Systems

All or some of the remote systems may be described separately in the remotesystem dictionary which is part of the directory configuration. Up to 5000 systemscan be declared.

Communications objects related to remote systems described in the enableddirectory configuration are dynamically configured, namely:

• they are dynamically created from directory information at each connectionrequest 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.

GCOS 7 View of the Network

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The advantage of incremental enabling is that the remote systems can be declaredin the directory rather than in the basic network configuration. When thisdescription is missing or empty, the generation processing will result in an emptydirectory.

Subdomain objects can also be addressed in this directory: they describe specificsubnetworks 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 ofcorrespondents. This description is optional but when present, is always includedin the correspondent dictionary which is part of the directory configuration. Up to10000 correspondents can be declared.

The information related to the service of correspondents may be modified during acommunications session using incremental generation and incremental enabling.Correspondents are taken into account dynamically, whereas information specificto TDS such as workstations and pools are taken into account only at cold start ofthe application concerned.

4.2.2 Network Configurations

An ISO network configuration primarily describes a collection of systems or nodesmutually interconnected by communications links, and how to establish these links.

A system is declared by a single directive which namely specifies its type andnetwork address. Using detailed low level description, each communicationsobject may be declared separately by its own low level directive.

The objects defined at network generation may be subsequently accessed byoperator commands.

Each system is described by a unique SYS (SYSTEM) directive. There aretherefore as many SYS directives as there are systems to be described.


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Using the SYS directive, the user has to supply for each system only its name andits functional relationship in the network by means of one of the followingattributes for each kind of system:

Local System: DSA or ISO address, lan-attributes

Passthrough: DSA or ISO address, psi-channel addressorDSA 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 mandatorybecause of their physical addresses (PSI or LAN).

Remote Systems still need to be configured but only when migrating network fromthe DSA world to that of ISO. OSI addressing itself no longer requires thesesystems to be configured.

Subdomains are used only to restrict the list of passthroughs for outwardconnections.

The DEFAULT directive allows changing the setting of specific protocol oradministrative attributes such as timer and retry-count which are common toseveral systems.

NOTES:1. Some low-level directives describing basic internal objects are also

available when specific needs on network configuration are necessary. Seethe manual Network Generation.

2. These low-level objects are also managed by DSAC administration.

3. DSA informations such as SCID (DSA200 address) still remain necessaryfor managing the administrative functions of the passthrough namely,SYSGEN, LOAD and DUMP of the Datanet and the CNP7.

GCOS 7 View of the Network

47 A4 92UC Rev02 4-5

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 necessaryfor 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 theNetwork Generation manual.


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❑

47 A4 92UC Rev02 5-1

5. GCOS 7 Network Administration

5.1 ISO/DSA and ISO Administration

DSAC (Distributed System Administration and Control) allows GCOS 7 toadminister an ISO/DSA or ISO network.

The RAEH (Remote Administrative Exchange Handler) server provides the DSACservices.

The DSAC services are:

• receiving a command from any system, local or remote and sending back theresulting response.

• sending a command from the local system for execution in another ISO/DSAsystem and receiving the response.

• journalizing events (sent by the local or remote systems) concerning the networkbehaviour.

• 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 SNMPmanager to manage the IPS communications of the FCP7.

• a SNMP manager, located in the OCS driver, able to administer a local SNMPagent (that is, in the same driver), or a remote SNMP agent.

All these functions are described in the manual Network User Guide.


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5.3 OCS Front End Management

The OCS Front End configuration loading and dump is performed when the OCSserver 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 thenecessary parameters for communication protocols execution. These parameters aredescribed in specific files referenced in the load scenario.

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

5.4 Administrative Function for FEP’s

Administrative functions for Datanet and CNP7 are GENERATION, LOAD andDUMP 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 forthe system to be administered.

The administrative functions for Datanet and CNP7 are described in the manualNetwork User Guide.

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

47 A4 92UC Rev02 g-1

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 PIDIt is the part of the PID module which is in charge of converting the session addressing from DSAto ISO, and vice versa.

B

BASIC NETWORK CONFIGURATIONPart of the network configuration which must always be present and cannot be swapped during acommunications session.

BASIC NETWORK CONFIGURATION DESCRIPTIONSet of directives describing the local system, its passthroughs and neighbors and possibly someremote systems. It may also comprise network administration and queue descriptions. It isembedded between NETWORK and ENDNETWORK directives.

BASIC NETWORK DICTIONARYDictionary which contains the names and locations of all communications objects staticallyconfigured and produced by a basic generation.

BASIC NETWORK GENERATIONNETGEN processing applied to a basic network configuration description. This processing cannormally be executed while a communications session is running. However, its enabling requiresthe communications session to be previously stopped.


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C

COMMUNICATIONS SESSIONThe 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.

CONFIGURATIONData resulting of the NETGEN generation processing applied to configuration descriptiondirectives.A full set of configurations comprises:

• the basic network configuration• the directory configuration• and the terminal configuration.

CONFIGURATION DIRECTORYPart of the network configuration which is optional and moreover can be fully changed orsuppressed during a communications session. It always contains the two dictionaries even if theyare empty.A basic network generation without directory configuration description results in an emptydirectory configuration available for any subsequent incremental generation.

CORRESPONDENTIn general terms, it is a local representation of a remote object, function or application associatedwith a name and a type, and network references to access it.

CORRESPONDENTS DICTIONARYDictionary which contains all the objects dealing with the communications service ofcorrespondents which are produced by a directory generation. It can be empty.

D

DICTIONARYContainer 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.

DIRECTIVEA 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.

Glossary

47 A4 92UC Rev02 g-3

DIRECTORYIt consists of two dictionaries:

• the remote-system dictionary (TSYS)• the correspondent dictionary (TCORR).

DIRECTORY CONFIGURATION DESCRIPTIONIt must be embedded between DIRECTORY and ENDDIRECTORY directives. It is mainlycomposed of two parts in any order:

Correspondent Description:Contains all the objects dealing with the communications service of correspondents. Thisdescription is optional, when present the generated objects are always all included into thecorrespondent dictionary (maximum 10000 correspondents).

Remote-system Description:Contains all or some remote systems up to 5000, accessible by the local system using passthroughsalready described in the basic configuration.

DIRECTORY GENERATIONNETGEN processing applied to a DIRECTORY configuration description.It can be:

• either associated with a basic generation, in which case it is enabled when the basicgeneration is enabled

• or launched separately, in which case it is incremental and its enabling requires a valid basicconfiguration to be already enabled.

Directory generation may result in an empty directory if the directory configuration description isempty.

F

FCP7FDDI Communications Processor 7 is an integrated communications controller which enables aDPS 7000 to access an FDDI network. FCP7 contains both an OSI stack and an IPS stack. TheOSI stack contains OSI layers 1 to 4 and serves both OSI and DIWS. The IPS stack contains theTCP, UDP, ICMP, and IP layers. The communications server associated with FCP7 is OCS (OpenCommunications Subsystem). FCP7 contains an RFC1006 transport layer enabling OSI/DIWSsessions to be run over a TCP/IP network.

FRONT-END PROCESSORSee pass-through.

FTPFTP (File Transfer Protocol) is a "de facto" TCP/IP standard for file transfers.


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G

GXTIGXTI is a programmatic interface which allows a GCOS 7 application to access a remoteapplication through ISO transport or TCP or UDP transport.

H

HETEROGENEOUS SYSTEMSystem 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. Sucha system can be any including another DPS 7000 running on releases prior to V6.

HOMOGENEOUS SYSTEMSystem 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 useAEP format. Such a system can only be a DPS 7000 running on releases from V6 onwards.

I

ISO-DSA PLUGSee PID.

L

LAN Extender SubsystemIn addition to the FCP7, the LAN Extender Subsystem provides a maximum configuration of5 FDDI SAS links, 8 Ethernet 802.3 ports, and 1 FDDI DAS link.

LOCAL SYSTEMThe unique DPS 7000 system running on GCOS-7 versions from V6 onwards for which the localview of the network is generated. It must be described before any other system.

N

NEIGHBORAny 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.

NETWORKThe most general term describing intercommunication between nodes and nodes, and nodes andend-users. The term may also have the more restrictive scope of the ISO network layerenvironment.

Glossary

47 A4 92UC Rev02 g-5

NETWORK ADMINISTRATIONSet of communications functions which regulate, monitor and control events in the network.

NETWORK ADMINISTRATION DESCRIPTIONThe 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 CONFIGURATIONThe 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 DESCRIPTIONSet of directives fully describing all the communications objects involved within the wholenetwork which are accessible by the local system. It always comprises a basic networkconfiguration description and where applicable, a directory configuration description.The basic network configuration description describes the view of the network from the standpointof the local DPS 7000 which accesses all the systems in the network either directly or by means ofother 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 systemdictionary which forms part of the directory configuration.

NFSNFS (Network File System) is a distributed file access facility. It supports client/serverarchitecture. An NFS client accesses files, an NFS server provides files for access.

NODESynonymous with system.

O

OCSOCS (Open Communications Subsystem) is the communication server associated to OCS FrontEnds which are FCP7 (FDDI Communication Processor 7) for DPS 7000 running in Bull Decorand VCP7 (Virtual Communication Processor 7) + network Adapter for DPS 7000 running incommodity Decor.

OPEN LAN ACCESS 7OPEN LAN ACCESS 7 is a communications module which handles the protocol and/or addressconversion from DSA to ISO. This mechanism allows DSA applications such as IOF, TDS, UFT towork with applications located in an ISO/DSA workstation (DIWS).


g-6 47 A4 92UC Rev02

P

PASSTHROUGHA neighbor acting as an intermediate thru which the local system accesses remote systems or othernetworks, and vice versa. Such a system front-ends the local system and acts as a go-between withremote systems.

PIDThe ISO/DSA plug module which interface between VCAM session and the Transport servers toallow the DSA applications to communicate with applications running on ISO/DSA work stations(DIWS).

PROTOCOLAR PIDThe part of the PID module in charge of converting session protocols from DSA to ISO, and viceversa.

R

REMOTE SYSTEMAny system which the local system accesses through the intermediary of a passthrough. Thedirective which describes it must appear after all the passthroughs.

S

SYSTEMThe functional position occupied by the system within the current network configurationdetermines its functional type, namely, local system, passthrough, neighbor or remote system.

Glossary

47 A4 92UC Rev02 g-7

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


g-8 47 A4 92UC Rev02

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

Glossary

47 A4 92UC Rev02 g-9

OPEN7 OPEN GCOS7 towards TCP/IP communicationsprotocols

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, thelayer) defining an OSI session over TCP/IP layers. TheRFC1006 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)


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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

Glossary

47 A4 92UC Rev02 g-11

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 protocolRFA

UM Unsolicited Message (DSAC)

UT User of Transport (OSI addressing)

VCAM Virtual Communications Access Method (sessioncommunication server)

VCP7 Virtual Communication Processor: it is the softwareadaptation in a commodity Decor of the FCP7 OCSFront End

WAN Wide Area Network

XCP Extended Cooperative Protocol

XOPEN Open to UNIX facilities

XTI XOPEN Transport Interface


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47 A4 92UC Rev02 i-1

Index

A

addressingfunction of lower layers 2-10function of LSAP in ISO/DSA 2-10function of mailbox in DSA 2-10function of SCID in ISO/DSA 2-10function of TSAP in ISO/DSA 2-10ISO/DSA 2-10OSI 2-13TCP/IP 3-4

AETapplication entity title 2-21

AFIcomponent of IDP 2-15

B

basic networkcomposition 4-1description 4-2

C

commands 1-12communications

description of servers 1-9TCP/IP 3-1

connection mechanisminward 2-38, 2-41inward frame reception by TNS 2-38inward from link layer 2-38inward from network layer 2-39

connection mechanism (continued)inward function of DNS 2-36inward function of TNS 2-38, 2-41ISO session in inward 2-41outward connectionless mode 2-37outward FEPS pseudo-transport 2-35outward network routing 2-37outward session routing 2-32outward TNS transport 2-37, 2-40selecting upper layers 2-36selecting upper layers in inward 2-40setting of frame in outward 2-38, 2-40

correspondentdeclaring TM 4-3declaring XCP 4-3

CSMA/CD 3-3

D

data link layerISO/DSA 2-9TCP/IP 3-3

directoryremote systems 4-2

DSPcomponent of NSAP 2-16domain specific part 2-16

F

FCP7 1-7FDDI 3-3FECM

description 1-9


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FEPSdescription 1-9use for ISO session 2-29

FIA 1-6FTP 3-2

G

GXTIdescription 1-10

I

IDIcomponent of IDP 2-16initial domain identifier 2-16

IDPcomponent of NSAP 2-15

inward connection mechanism 2-35, 2-38, 2-41

IP protocol 3-3ISL 1-1, 1-6

administration of connection 3-10ISO

network configurations 4-3ISO/DSA

addressing 2-10, 2-23application layer 2-5transport layer 2-6

ISO-DSA plugfunctions 2-23

L

LAPB 3-3layer

ISO/DSA implementation 2-5ISO/DSA presentation 2-5TCP/IP application 3-2TCP/IP data link 3-3TCP/IP network 3-3TCP/IP physical 3-3TCP/IP presentation 3-2TCP/IP session 3-2TCP/IP transport 3-2

LLC sub-layerISO/DSA 2-9

LLC1 sub-layerTCP/IP 3-3

LNI 1-6LNM 1-6

M

MAC sub-layerISO/DSA 2-9TCP/IP 3-3

MainWay 2000 1-8MPC 1-6

N

NETGEN 1-11network

examples of configurations 1-3ISO configurations 4-3

network layerISO/DSA 2-8TCP/IP 3-3

NFS 3-2NSAP

OSI address description 2-15special format for RFC1006 2-19

O

OCSdescription 1-9

OPEN LAN ACCESS 7description 1-10

OSI addressingselector 2-14service access point 2-14

P

physical layerTCP/IP 3-3

Index

47 A4 92UC Rev02 i-3

PIDaddress conversion mechanism 2-25functions 2-23protocol conversion mechanism 2-24

presentation layerTCP/IP 3-2

PSAP addressdescription 2-21

Q

QMONdescription 1-9

QOSquality of service 2-34

R

RAEHdescription 1-9

RFC1006description 1-11transport layer 2-7

S

SCID 2-10Session Control Identifier 2-10session layer

ISO/DSA 2-5TCP/IP 3-2

SMTP 3-2SNMP 3-2SPA 1-6SSAP address

description 2-21subdomain

routing 2-33system

declaring in ISO 4-3

T

TCP transport 3-2TCP/IP

addressing 3-4application layer 3-2data link layer 3-3description 1-11network layer 3-3overview 3-1physical layer 3-3presentation layer 3-2session layer 3-2transport layer 3-2

Telnet 3-2TNS

description 1-9extension for ISO session 2-29implementation of ISO layers 3-10implementation of transport 2-29

Token Bus 3-3Token Ring 3-3transport

connection 2-6connection through GXTI 2-42

transport layerTCP/IP 3-2

TSAPTransport Service Access Point 2-10

TSAP addressdescription 2-20

TSELtransport selector 2-20

U

UDP transport 3-2

V

VCAMdescription 1-10function 2-3

VCP7 2-11VCP7 Controller 1-7


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X

X25 3-3administration of connection 3-10

XTI 3-2