About This Manual

This manual explains how to write programs with the X/Open Transport Interface (XTI) calls, STREAMS I/O calls, and the Berkeley Software Distribution (BSD) socket calls. For XTI and sockets, it provides conceptual and programming information. Additionally, it explains how to port applications from Transport Layer Interface (TLI) to XTI and from sockets to XTI. For STREAMS, this manual explains any differences between the Digital UNIX® It also provides information on the Digital UNIX Extensible System Network Management Protocol (eSNMP) application programming interface.

After reading this manual, you should be able to:

Understand the programming support provided in Digital UNIX for networking
Write an XTI application by using either connection-oriented or connectionless service
Understand the Digital UNIX implementation of STREAMS
Write a socket application
Understand the differences between TLI and XTI and between sockets and XTI
Write an eSNMP application

Audience

This manual addresses experienced UNIX programmers. We assume you are familiar with the following:

C language
Programming interfaces for UNIX operating systems
Basic networking concepts, including an understanding of the Open Systems Interconnection (OSI) 7-layer model
Efforts required to write networking applications

New and Changed Features

This revision of the Network Programmer's Guide contains the following changes:

A new section has been added to Chapter 3 that provides information on the XPG4 version of XTI. This section includes the major differences between the XPG3 and XPG4 versions, migration, and maintaining existing XTI programs.
Chapter 4 has been revised. The chapter now provides information on the XPG4 compliant version of the sockets programming interface. It also includes a section that compares the BSD, XPG3, and XPG4 interfaces.
Chapter 6 has been added to provide information on the Extensible Simple Network Management Protocol (eSNMP) application programming interface.
Chapter 7 has been added to provide information on the ifnet STREAMS module.

Organization

This manual is organized as follows:

Chapter 1 Provides an overview of XTI, STREAMS, sockets, and the programming tasks required for network applications.

Chapter 2 Describes the dlb pseudodriver, which implements a subset of the the Data Link Provider Interface (DLPI).

Chapter 3 Describes the fundamental concepts associated with XTI, how to write connection-oriented and connectionless applications, compatibility issues with TLI, and how to port applications to XTI. XTI errors are also covered in this chapter.

Chapter 4 Describes the concepts associated with the 4.3BSD socket interface, and how to write socket applications.

Chapter 5 Describes Digital UNIX's STREAMS implementation.

Chapter 6 Describes Digital UNIX's Extensible System Network Management Application Programming Interface.

Chapter 7 Describes the ifnet STREAMS module and dlb STREAMS pseudodriver communication bridges.

Appendix A Provides a sample STREAMS module.

Appendix B Provides XTI and sockets programming examples.

Appendix C Provides Transport Protocol Control (TCP) specific programming information.

Appendix D Provides information required by token ring driver developers.

Appendix E Describes the Data Link Interface (DLI) and provides programming examples.

This guide also contains a glossary of terms and an index.

Related Documents

For general information about programming with Digital UNIX, refer to the Programmer's Guide.

For additional information about XTI, refer to the following manuals:

X/Open Portability Guide Volume 7: Networking Services, ISBN 0-13-685892-9
Application Environment Specification (AES) Operating System Programming Interfaces Volume, ISBN 0-13-043522-8, published by Prentice-Hall, includes all of the mandatory XTI calls
X/Open CAE Specification: Networking Services, Issue 4 ISBN 1-85912-049-0

For additional information about the STREAMS I/O framework, refer to the following manuals:

Programmer's Guide: STREAMS. Englewood Cliffs:Prentice-Hall, Inc., 1990. This manual explains how to write applications, modules, and device drivers with STREAMS.
AT&T System V Release 4 Programmer's Reference Manual. Englewood Cliffs:Prentice-Hall, Inc., 1989. This manual contains the reference pages for all programming interfaces, including those for STREAMS.
IAT&T System V Release 4 System Administrator's Reference Manual. Englewood Cliffs:Prentice-Hall, Inc., 1989. This manual contains the reference pages for STREAMS ioctl commands.
Transport Provider Interface (TPI) Specification, yet to be published by AT&T.

For additional information about the 4.3BSD socket interface, refer to the following books:

Internetworking with TCP/IP: Principles, Protocols, and Architecture. Englewood Cliffs:Prentice-Hall, Inc., 1988. This book, by Douglas Comer, includes a chapter that describes the socket interface.
Design and Implementation of the 4.3BSD UNIX Operating System. Reading:Addison-Wesley Publishing Company, 1989. This book, by Leffler, McKusick, Karels, and Quarterman, includes information about the purpose and use of sockets.

For information about administering networking interfaces, refer to the System Administration guide and the Network Administration guide.

The printed version of the Digital UNIX documentation set is color coded to help specific audiences quickly find the books that meet their needs. (You can order the printed documentation from Digital.) This color coding is reinforced with the use of an icon on the spines of books. The following list describes this convention:

Audience Icon Color Code

General users G Blue

System and network administrators S Red

Programmers P Purple

Device driver writers D Orange

Reference page users R Green

Some books in the documentation set help meet the needs of several audiences. For example, the information in some system books is also used by programmers. Keep this in mind when searching for information on specific topics.

The Documentation Overview, Glossary, and Master Index provides information on all of the books in the Digital UNIX documentation set.

Reader's Comments

Digital welcomes any comments and suggestions you have on this and other Digital UNIX manuals.

You can send your comments in the following ways:

Fax: 603-881-0120 Attn: UEG Publications, ZK03-3/Y32
Internet electronic mail: readers_comment@zk3.dec.com
A Reader's Comment form is located on your system in the following location:
```
/usr/doc/readers_comment.txt
```
Mail:
Digital Equipment Corporation
UEG Publications Manager
ZK03-3/Y32
110 Spit Brook Road
Nashua, NH 03062-9987
A Reader's Comment form is located in the back of each printed manual. The form is postage paid if you mail it in the United States.

Please include the following information along with your comments:

The full title of the book and the order number. (The order number is printed on the title page of this book and on its back cover.)
The section numbers and page numbers of the information on which you are commenting.
The version of Digital UNIX that you are using.
If known, the type of processor that is running the Digital UNIX software.

The Digital UNIX Publications group cannot respond to system problems or technical support inquiries. Please address technical questions to your local system vendor or to the appropriate Digital technical support office. Information provided with the software media explains how to send problem reports to Digital.

Conventions

This document uses the following typographic conventions:

%
$ A percent sign represents the C shell system prompt. A dollar sign represents the system prompt for the Bourne and Korn shells.

# A number sign represents the superuser prompt.

% cat Boldface type in interactive examples indicates typed user input.

file Italic (slanted) type indicates variable values, placeholders, and function argument names.

[ | ]
{ | } In syntax definitions, brackets indicate items that are optional and braces indicate items that are required. Vertical bars separating items inside brackets or braces indicate that you choose one item from among those listed.

. . . In syntax definitions, a horizontal ellipsis indicates that the preceding item can be repeated one or more times.

cat(1) A cross-reference to a reference page includes the appropriate section number in parentheses. For example, cat(1) indicates that you can find information on the cat command in Section 1 of the reference pages.

[Return] In an example, a key name enclosed in a box indicates that you press that key.

Ctrl/x This symbol indicates that you hold down the first named key while pressing the key or mouse button that follows the slash. In examples, this key combination is enclosed in a box (for example, [Ctrl/C]).

Chapter 1	Provides an overview of XTI, STREAMS, sockets, and the programming tasks required for network applications.
Chapter 2	Describes the `dlb` pseudodriver, which implements a subset of the the Data Link Provider Interface (DLPI).
Chapter 3	Describes the fundamental concepts associated with XTI, how to write connection-oriented and connectionless applications, compatibility issues with TLI, and how to port applications to XTI. XTI errors are also covered in this chapter.
Chapter 4	Describes the concepts associated with the 4.3BSD socket interface, and how to write socket applications.
Chapter 5	Describes Digital UNIX's STREAMS implementation.
Chapter 6	Describes Digital UNIX's Extensible System Network Management Application Programming Interface.
Chapter 7	Describes the `ifnet` STREAMS module and `dlb` STREAMS pseudodriver communication bridges.
Appendix A	Provides a sample STREAMS module.
Appendix B	Provides XTI and sockets programming examples.
Appendix C	Provides Transport Protocol Control (TCP) specific programming information.
Appendix D	Provides information required by token ring driver developers.
Appendix E	Describes the Data Link Interface (DLI) and provides programming examples.

Audience	Icon	Color Code
General users	G	Blue
System and network administrators	S	Red
Programmers	P	Purple
Device driver writers	D	Orange
Reference page users	R	Green

`%` `$`	A percent sign represents the C shell system prompt. A dollar sign represents the system prompt for the Bourne and Korn shells.
`#`	A number sign represents the superuser prompt.
`%` `cat`	Boldface type in interactive examples indicates typed user input.
`file`	Italic (slanted) type indicates variable values, placeholders, and function argument names.
[ \| ] { \| }	In syntax definitions, brackets indicate items that are optional and braces indicate items that are required. Vertical bars separating items inside brackets or braces indicate that you choose one item from among those listed.
. . .	In syntax definitions, a horizontal ellipsis indicates that the preceding item can be repeated one or more times.
`cat`(1)	A cross-reference to a reference page includes the appropriate section number in parentheses. For example, `cat`(1) indicates that you can find information on the `cat` command in Section 1 of the reference pages.
`[Return]`	In an example, a key name enclosed in a box indicates that you press that key.
Ctrl/x	This symbol indicates that you hold down the first named key while pressing the key or mouse button that follows the slash. In examples, this key combination is enclosed in a box (for example, `[Ctrl/C]`).