Data Link Provider Interface (DLPI)
Data Link Provider Interface (DLPI)
Copyright © 1997 The Open Group


CAE Specification
Data Link Provider Interface (DLPI)
X/Open Document Number: C614
ISBN: 1-85912-196-9

©February 1997, The Open Group All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission of the copyright owners.

The base document for this specification was Copyright 1991 by UNIX International. See Acknowledgements.

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This Document
This document is a CAE Specification. It specifies a STREAMS kernel-level instantiation of the ISO Data Link Service Definition ISO/IEC 8886 and Logical Link Control ISO/IEC 8802-2 (LLC). Where the two standards do not conform, ISO/IEC 8886 prevails.

The Data Link Provider Interface (DLPI) enables a data link service user to access and use any of a variety of conforming data link service providers without special knowledge of the provider's protocol.

Specifically, the interface is intended to support X.25 LAPB, BX.25 level 2, SDL C, ISDN LAPD, Ethernet, CSMA/CD, FDDI, token ring, token bus, Bisync, Frame Relay, ATM, Fiber Channel and HIPPI. Readers should note that the list of data links supported by the interface may be augmented and is published on the World-Wide Web in the DLPI Corrigendum U019 at (under Sales and Ordering). This Corrigendum will contain relevant additional information such as recognised implementors' agreements/guidelines for common data link providers. A printed copy of this Web page may also be obtained from The Open Group on request (address on inside front page of this specification).

Among the expected data link service users are implementations of the OSI network layer and SNA path control.

The interface specifies access to data link service providers, and does not define a specific protocol implementation. Thus, issues of network management, protocol performance, and performance analysis tools are beyond the scope of this document and should be addressed by specific implementations of a data link provider. However, accompanying each provider implementation should be information that describes the protocol-specific behavior of that provider. Currently, there are plans to come up with a set of implementors' agreements/guidelines for common data link providers. These agreements will address issues such as DLSAP address space, subsequent addresses, ppa access and control, QOS, supported services etc.

Intended Audience
This specification assumes the reader is familiar with OSI Reference Model terminology, OSI Data Link Services, and STREAMS.
Document Structure

A Glossary and Index are also provided.

Typographical Conventions
The following typographical conventions are used throughout this document:

Trade Marks

Motif®, OSF/1®, and UNIX® are registered trademarks and the "X Device"TM; and The Open GroupTM; are trademarks of The Open Group.


The base document from which this specification is derived was published as Copyright 1991 UNIX International, Inc.

The following copyright notice was attached to the document:

Permission to use, copy, modify, and distribute this documentation for any purpose and without fee is hereby granted, provided that the above copyright notice a ppears in all copies and that both that copyright notice and this permission not ice appear in supporting documentation, and that the name UNIX International not be used in advertising or publicity pertaining to distribution of the software without specific, written prior permission. UNIX International makes no representations about the suitability of this documentation for any purpose. It is provided "as is" without express or implied warranty.

Referenced Documents

The following documents are referenced in this specification:

ISO/IEC 8886

ISO/IEC 8886:1996, Information Technology - Open Systems Interconnection - Data Link Service Definition.

ISO/IEC 8802-2

ISO/IEC 8802-2:1994, Information Technology - Telecommunications and Information Exchange between Systems - Local and Metropolitan area Networks - Specific Requirements - Part 2: Logical Link Control.


UNIX Press (A Prentice Hall Title) book "STREAMS Modules and Drivers", published 1992, ISBN 0-13-066879-6.


CCITT Recommendation X.200, "Reference Model of Open Systems Interconnection for CCITT Applications", 1984.

XNS, Issue 5

CAE Specification, February 1997, Networking Services, Issue 5 (ISBN: 1-85912-165-9, C523).

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