Introduction to Networking for NonStop S-Series Servers

Open Systems Interconnection (OSI) Network

Connections

Introduction to Networking for HP NonStop S-Series Servers—520670-005

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Upper Layer Interfaces (OSI/AS)

HP NonStop OSI/AS is an implementation of the OSI Session and Presentation Layers

(layers 5 and 6) and the Association Control Service Element (ACSE) in the

Application Layer (layer 7). It provides the means for an application running on a

NonStop system to communicate with other applications in a multivendor OSI network.

OSI/AS gives your application direct access to layer 5 (Session), layer 6

(Presentation), or layer 7 (Application) functions through a single, standards-based

programmatic interface. The OSI/AS API consists of procedures modeled after OSI

primitives, allowing you to port existing OSI applications onto NonStop systems.

OSI/AS lets you develop applications for cooperative processing with systems from HP

or other manufacturers such as DEC or Honeywell-Bull.

OSI/AS uses the services of other HP NonStop OSI products for network access.

These products are described in Transport Layer Interface (OSI/TS) on this page and

Network and Data Link Interfaces on page 8-15.

Transport Layer Interface (OSI/TS)

HP NonStop OSI/TS is an implementation of the OSI Transport Layer (layer 4). It

provides reliable transport of data over a wide range of network types and data links.

NonStop OSI/TS gives OSI/AS applications access to LAN and WAN environments,

including the Internet. Applications can use the same OSI/AS interface for all

environments, simplifying application development and minimizing maintenance. You

can also write applications that use OSI/TS processes directly for specialized

application functions.

NonStop OSI/TS supports all Transport Layer classes defined in the OSI Reference

Model. It also supports the Connectionless Network Layer Protocol (CLNP) for use

over either a LAN or an X.25 packet-switched data network (PSDN). CLNP is used

automatically when you run OSI/TS on a LAN; in the case of an X.25 network, you can

choose CLNP as a configuration option.

OSI/TS can also connect to the NonStop TCP/IP subsystem at the Transport Layer in

order to provide communication with other servers and clients over a TCP/IP network

such as the Internet.

Note. CLNP is sometimes called the OSI Internet Protocol (IP). It is similar, but not identical,

to the internet protocol defined by TCP/IP.