.NC "Introduction".sh 1 "Introduction".ppThis document describes the design and implementation of the ISOtransport 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..)ffor 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), theISO connectionless network service (CLNS)and aconnection-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 completeISO CONS, but contains enough of the CONS to supportthe COTS and the CLNS (in the latter case, the CONS can beviewed as a subnetwork service)..ppThe purposes of this document are.ip "1) "to describe the transport service and the software interfacebetween the user and provider of this service,.ip "2) "to describe the network service and the software interface itprovides,.ip "3) "to describe the design of the software which providesthese services, and.ip "4) "to provide a guide for readers who are perusing or maintainingthe ARGO kernel source code..ppIt is assumed that the reader is familiar with the \fBC\fRprogramming language,with Unix conventions, and with the ISO specifications listed in Appendix A..sh 1 "Organization".ppThis document is composed of several chapters.Chapter One contains this introduction. Chapter Two presents adefinition of terms and phrases used throughout the document.Chapter Three describes the transport service interface, which isthe interface between the transport protocol implementation software and the transport user software.Chapter Four describes the network service interface, and the interfaceabove and below the network layer.Chapter Five explains the format of an OSI address.Chapter Six describes thethe architecture of the interprocess communication support in the kernel, which to a large degree mandatesthe design of a protocol implementation for a 4.3 Unix kernel.Chapter Seven describes the design of this transportprotocol 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 fortesting 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..ppSeveral conventions are followed in this document.All procedure names and system call names are followedby a pair of parentheses, for example,\fIread()\fR.References to manual pages consist of the name of themanual page, followed by the section in whichthe man page is found: \fIread(2)\fR.