TS Supplement (Includes RFC-1006 Support)

1 Introduction to RFC-1006

107751 Tandem Computers Incorporated 1–1

This section contains the following information:

Overview of Tandem OSI architecture

Introduction to the Tandem TCP/IP subsystem

Changes in the Transport Layer when using RFC-1006

Tandem OSI/AS and OSI/TS have implemented the Request for Comments (RFC)

1006 standard entitled “ISO Transport Service on Top of the TCP,” Version 3. This

standard, developed for the Internet community, defines how the ISO transport

service can be implemented on top of the Transmission Control Protocol (TCP), which

is a Transport Layer protocol specified in the Internet Reference Model.

Using the RFC-1006 standard, OSI applications such as X.400, X.500, and FTAM (and

other OSI/AS or OSI/TS applications) that communicate over OSI/AS and OSI/TS

can now communicate with other servers and clients over a TCP/IP network

connection.

RFC-1006 was implemented such that:

No changes are required for existing upper layer applications that wish to use

RFC-1006.

No functional changes were made to OSI/AS and OSI/TS that would affect non-

RFC-1006 users.

No limitations are placed on the use of TCP/IP for RFC-1006 users. That is, RFC-

1006 users make use of TCP/IP as any other TCP/IP user would.

Note The terms client and server are used in this manual as is customary in TCP/IP literature. A client is a

process that sends requests to the server and waits for it to respond. A server is a process that offers a

service that can be used over the network; it accepts a request, performs the specified service, and

returns the result to the requester. The client-server model is the same model known in Tandem

literature as the requester-server model (a client is the same as a requester).

Throughout this manual, the term RFC-1006 (with a hyphen) refers to the Tandem implementation of the

standard, and the term RFC 1006 (without a hyphen) refers to the RFC 1006 Internet standard.

Overview of the

Tandem OSI

Architecture

Figure 1-1 illustrates how the various layers of the OSI Reference Model are supported

for users of OSI/AS and OSI/TS over:

A local area network (LAN), the TLAM subsystem

A wide area network (WAN), the X25AM subsystem

The Internet (TCP/IP subsystem)

Tandem OSI/TS connects to TCP/IP at the Transport Layer within the OSI/TS

subsystem, by specifying TCP/IP as the Network Service Provider (NSP) process.

TCP/IP, in turn, connects to X25AM and TLAM.