.NC "Introduction"
.sh 1 "Introduction"
.pp
This document describes the design and implementation of the ISO
transport and network layers written for the ACIS Operating System,
the IBM ACIS port of Berkeley 4.3 Unix\**
.(f
\** Unix is a registered trademark of AT&T.
.)f
for the IBM RT PC,
hereafter called AOS.
Collectively, this work is called the Wisconsin ARGO kernel. 
The ARGO kernel supports the 
the connection-oriented ISO transport service (COTS), the
ISO connectionless network service (CLNS)
and a
connection-oriented network service (CONS).
The COTS is provided by the ISO transport protocol TP,
ISO 8073 Revised.
The CLNS is provided by the connectionless network protocol,
ISO 8473.
The CONS is provided by the X.25 protocols.
The ARGO implementation of the CONS is not a complete
ISO CONS, but contains enough of the CONS to support
the COTS and the CLNS (in the latter case, the CONS can be
viewed as a subnetwork service).
.pp
The purposes of this document are
.ip "1) "
to describe the transport service and the software interface
between the user and provider of this service,
.ip "2) "
to describe the network service and the software interface it
provides,
.ip "3) "
to describe the design of the software which provides
these services, and
.ip "4) "
to provide a guide for readers who are perusing or maintaining
the ARGO kernel source code.
.pp
It is assumed that the reader is familiar with the \fBC\fR
programming language,
with Unix conventions, and with the ISO specifications listed in Appendix A.
.sh 1 "Organization"
.pp
This document is composed of several chapters.
Chapter One contains this introduction. Chapter Two presents a
definition of terms and phrases used throughout the document.
Chapter Three describes the transport service interface, which is
the interface between the transport protocol implementation software and the transport user software.
Chapter Four describes the network service interface, and the interface
above and below the network layer.
Chapter Five explains the format of an OSI address.
Chapter Six describes the
the architecture of the interprocess communication support in the 
kernel, which to a large degree mandates
the design of a protocol implementation for a 4.3 Unix kernel.
Chapter Seven describes the design of this transport
protocol implementation,
including descriptions of implementation options.
Chapter Eight describes the design of the network layer implementation.
Chapter Nine describes the way errors are handled in the system.
Chapter Ten summarizes the methods used for
testing and debugging the ARGO kernel.
Appendix A is a list of the applicable ISO standards.
.\" The manual pages relevant to the transport and network layers
.\" are included as Appendix B.
.pp
Several conventions are followed in this document.
All procedure names and system call names are followed
by a pair of parentheses, for example,
\fIread()\fR.
References to manual pages consist of the name of the
manual page, followed by the section in which
the man page is found: \fIread(2)\fR.