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DIGITAL SNA access server migration guide

[Top] [Prev] [Next] [Index] [Contents] DIGITAL SNA Access Server Migration Guide 

How the Access Server and SNA Server Work Together

Together, the Access Server and the SNA Server function as a gateway between a DECnet or TCP/IP network and an IBM host. The combination of the Access Server and the SNA Server, working together, is called the Access Server Gateway. The Access Server Gateway provides connectivity between existing DIGITAL OpenVMS access routines and IBM hosts. This new gateway may replace a DECnet SNA Gateway or be implemented alongside an existing DECnet SNA Gateway. 
In this guide, DIGITAL OpenVMS SNA applications are referred to collectively as access routines
OpenVMS access routines on any DECnet SNA Gateway can use the Access Server Gateway with no modifications to those access routines. The Access Server Gateway supports existing OpenVMS SNA access routines (except APPC/LU6.2 access routines) and enables the reuse of LU names established with the DECnet SNA Gateways. The Access Server can map DECnet SNA Gateway LU names to LU names that are recognized by SNA Server. In this guide, and in the Access Server, DECnet SNA Gateway LU names are referred to as old-style LU names or old-style names

You can run the Access Server Gateway on any Intel or DIGITAL Alpha system that is running the Windows NT Server. Each Access Server Gateway that communicates with the IBM host must have the Access Server, the SNA Server, and Windows NT Server installed and running on the same node. 

An Access Server Gateway may be connected to the IBM host network in a variety of ways: 

  • Directly to the mainframe using one of the following high-performance connection types: Open System Adapter (Token Ring, Ethernet, or FDDI connections) or Channel connection (ESCON or Bus and Tag).

  • Via a front-end processor (FEP) (a PU type 4 device), using at least one of the following connection types: Token Ring, Ethernet, FDDI, SDLC, and X.25
The SNA Server supports the following standard protocols: terminal sessions (LU2), printer sessions (LU1 and LU3), LUA general purpose applications (LU0-LU3). A given physical connection may support any one or any combination of the standard protocols. 

Figure 1-2 shows how the SNA Server and the Access Server might work together in a network configuration. Communication between the IBM host and the OpenVMS system occurs through the Windows NT Server, which hosts both the DIGITAL SNA Access Server and the Microsoft SNA Server. This is a generic configuration that would be used with any of the following connectivity options: SDLC, 802.2, X.25, DFT, Channel, or TwinAx. 

Figure 1-2: Network Configuration with SNA Server and Access Server

Network Configuration with SNA Server and Access Server 

You can replace all or part of your DECnet SNA Gateway (except LU6.2 functionality) with the gateway capabilities of the Access Server and SNA Server running on a Windows NT Server. Proper planning and implementation can significantly minimize the impact of this migration on the existing system and its users. The rest of this guide steps you through the stages of your migration. 

[Top] [Prev] [Next] [Index] [Contents] DIGITAL SNA Access Server Migration Guide