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Implementing MS's SNA Server in the 400 Environmen

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It's Sunday at 11:47 p.m. Manuals, diskettes, and hair are strewn around the computer room like the aftermath of a tornado. I've got to get this gateway configured before the big client/server demo on Monday morning. I'm starting to panic-complex configurations, obscure client software. My heart races as I hear somebody scream. Suddenly, I realize it's me. I wake in a pool of sweat and realize it was a nightmare. In a flood of relief, I remember that I don't have to deal with that mess. There is a better way.

Last month, we explained Systems Network Architecture (SNA) gateways. (See "LAN Gateways and Microsoft's SNA Server," MC, March 1995.) This month, we'll show you what it takes to implement Microsoft's SNA Server Version 2.1 in an AS/400 environment. Much can be said for simplicity and strength, and this product has both.

Before I discuss the installation, I'll review our environment. The environment consists of an AS/400 model F35 running OS/400 V2R3 on an 802.2 Ethernet network with both Windows NT and Novell NetWare 3.12 servers. The clients are running Windows for Workgroups 3.11 and Windows NT 3.5 Workstation with NetBEUI and IPX protocol stacks.

We have Novell NetWare for SAA 1.31b running on a NetWare 3.12 server. NetWare for SAA is an SNA gateway that runs with Novell NetWare. It functions like SNA Server, allowing multiple clients to connect to an AS/400 through a gateway over a single network transport protocol. IBM recommends NetWare for SAA for LAN-to-AS/400 connectivity.

Installation Overview

1 is a flowchart detailing the four-step process of installing SNA Server on the LAN. First, the server software is installed on a Windows NT Server machine. The server is then configured to communicate with the AS/400. Next, a 5250 emulation screen is only a double-click away.

Figure 1 is a flowchart detailing the four-step process of installing SNA Server on the LAN. First, the server software is installed on a Windows NT Server machine. The server is then configured to communicate with the AS/400. Next, a 5250 emulation screen is only a double-click away.

The SNA Server package includes manuals that detail most aspects of SNA Server and an instructional video that guides you through the installation and configuration process. The video spends a lot of time explaining SNA and the 3270 architecture, but it also addresses the AS/400 and the 5250 environment.

Server Software Installation

Installing SNA Server is as simple as installing other Windows products, beginning with the familiar D:SETUP. (D: is used because the software is supplied on a CD-ROM.) In fact, installing the server software takes only 13 mouse clicks, all to select the default values.

The first time you run the setup program, it copies the necessary files and prompts for information regarding the configuration.

One of the configuration questions concerns the domain of the server. (A domain is a set of servers and workstations grouped together for efficiency and security. Domains are created when the NT network is set up.)

The question is what role this server will play in the domain-primary, backup, or member server. The primary server stores the configuration file for all SNA Servers in a domain. Backup servers, which are optional, store read-only copies of the configuration file and can be used to load a backup configuration in the event of a problem with the primary server. Member servers do not maintain copies of the configuration file.

In a single server environment, the server must be designated as primary. In a multiple server environment, one server should be designated as primary for the entire domain, and others should be designated as backups.

During installation, you also choose a link service. The link service specifies how SNA Server talks to the network interface board installed in your computer. In our environment, we use the data link control (DLC) 802.2 link service, a standard for token-ring and Ethernet configurations. SNA Server supports many link services, including X.25, SDLC, and twinax. (Twinax cards require additional third-party drivers supplied by the cards' manufacturers.)

You can run the setup program again to add additional link services, change the role of the server, or change the client/server protocol. By rerunning the setup program, you can also remove SNA Server. If you want to remove SNA Server from your machine, it is essential that you do it using the SETUP program, so it is removed entirely. Otherwise, SNA Server registry entries will remain, which may cause a problem if you later need to reinstall SNA Server.

Once the server software is installed, use the administration program included with SNA Server to configure the software to communicate with your AS/400.

Server Software Configuration

Server configuration is a little more involved, but the SNA Server manuals explain, step-by-step, how to configure SNA Server to communicate with the AS/400. They include a cross-reference table that shows the parameters required by SNA Server and where the corresponding values are on the AS/400.

My AS/400 Ethernet adapter already had a line description created for it. The Autocreate controller (AUTOCRTCTL) parameter on the line description was set to *YES, and the Autoconfigure devices (QAUTOCFG) system value was set to "1", so the only thing I had to do was tell SNA Server about the AS/400. The AS/400 needed no configuration. The parameters required, ADPTADR and EXCHID, can be retrieved by displaying the line description for the Ethernet adapter. Just follow the process described in the manual and enter these values in the appropriate places.

The network name and AS/400 control point name values are shown on the Display Network Attributes (DSPNETA) screen. The network name is entered in the dialog box shown in 2. Use the Connection Properties screen shown in 3 to enter the connection name; the link service is configured by pressing the Setup button. 4 is the 802.2 Setup screen, where you enter the AS/400 line description parameters and the network and AS/400 control print names. These three screens comprise the bulk of the server configuration setup.

The network name and AS/400 control point name values are shown on the Display Network Attributes (DSPNETA) screen. The network name is entered in the dialog box shown in Figure 2. Use the Connection Properties screen shown in Figure 3 to enter the connection name; the link service is configured by pressing the Setup button. Figure 4 is the 802.2 Setup screen, where you enter the AS/400 line description parameters and the network and AS/400 control print names. These three screens comprise the bulk of the server configuration setup.

The configuration process took me about 20 minutes. Someone who is familiar with the setup should be able to configure the server in less than ten minutes. One nice feature of SNA Server is that, once you complete the installation, you can test the connection right on the server with the 5250 applet. (An applet is a mini-application supplied for testing purposes.)

Client Installation and Configuration

I installed the Windows for Workgroups and the Windows NT Workstation client software. Installing the client software is the same on both platforms, with one exception. The client software for Windows NT Workstation allows multiple networking protocols, while Windows for Workgroups allows only a single protocol at a time.

For each client software installation, you must choose whether it will be a local or remote client. Local clients look across the network to automatically find and use any active SNA Server. Remote clients require that you enter the name of the server manually because they look for that server directly instead of searching the network. In both cases, once a server is found, any other SNA Servers on the network become known to the client immediately.

Windows NT Workstation Client

Installing the SNA Server client for Windows NT Workstation with the default values in this environment requires seven clicks of the mouse and no typing. I chose the local client option. The NT client setup allows you to install the administration program for the server, which I did. Administering the server from a client means you can configure and troubleshoot the server without leaving your desk.

Once the Windows NT client software is installed, you can configure the 5250 emulator applet. On the Session Configuration screen (see 5), a few parameters must be entered. The local LU alias is the name of the SNA Server to which you will be connecting. The partner LU alias is the local control point name on the AS/400; you can leave both as default, meaning both will be retrieved from the SNA Server, or you can enter the actual value retrieved with the DSPNETA command. Enter this information along with the device name, select Connect from the menu, and bingo, the AS/400 devices are automatically created and you've got an AS/400 sign-on screen! That's all there is to setting up an NT client.

Once the Windows NT client software is installed, you can configure the 5250 emulator applet. On the Session Configuration screen (see Figure 5), a few parameters must be entered. The local LU alias is the name of the SNA Server to which you will be connecting. The partner LU alias is the local control point name on the AS/400; you can leave both as default, meaning both will be retrieved from the SNA Server, or you can enter the actual value retrieved with the DSPNETA command. Enter this information along with the device name, select Connect from the menu, and bingo, the AS/400 devices are automatically created and you've got an AS/400 sign-on screen! That's all there is to setting up an NT client.

Windows 3.x Client

The Windows 3.x client was more difficult to configure on my machine. Installing the software is the same as with the NT client (again I chose the local client option) with the exception of client/server protocols. As mentioned previously, you can choose only one protocol for the Windows for Workgroups client. I chose the Microsoft Networking (NetBEUI) protocol as shown in 6.

The Windows 3.x client was more difficult to configure on my machine. Installing the software is the same as with the NT client (again I chose the local client option) with the exception of client/server protocols. As mentioned previously, you can choose only one protocol for the Windows for Workgroups client. I chose the Microsoft Networking (NetBEUI) protocol as shown in Figure 6.

The difficulty arose when I tried to run the client. When I double-clicked on the 5250 emulator icon, the machine froze for a second as it scanned the network for SNA Servers. Then it said I couldn't connect to the server because of error number 546. This error message was strange because my machine is configured with a dual boot setup-Windows NT and DOS/Windows for Workgroups- and the 5250 emulator had come up easily under Windows NT.

The reference manual offered no explanation for the error, merely repeating the error message displayed on my screen and providing no additional references. The Readme file on the CD explained how to apply a patch to the Server version of NT that I am using, but the patch did not help. I searched the documentation on the CD (which was difficult without a built-in search engine) and did not find any mention of a resolution for the 546 error.

Eventually, I turned to CompuServe for help. There, I found the answer to my troubles. It seems that Microsoft regularly patrols the MSSNA conference to provide hapless users with informed answers to their questions. A quick scan netted me a message with five possible causes for the problem I was having.

The solution was to add an entry to the SYSTEM.INI file. If you specify Microsoft Networking for the client protocol during setup, and you are using IPX/SPX with NetBIOS on your machine (a common setup if you are running both NetWare and NT servers), you need to add the following entry to the network section of the SYSTEM.INI file:

DirectHost=NO

This entry prevents a Windows for Workgroups client using IPX from trying to go into a mode called "direct hosting," which Microsoft says is more efficient-if it works. Once I added this line to the SYSTEM.INI file and restarted Windows, I configured my session the same way I configured my Windows NT session (see 5).

This entry prevents a Windows for Workgroups client using IPX from trying to go into a mode called "direct hosting," which Microsoft says is more efficient-if it works. Once I added this line to the SYSTEM.INI file and restarted Windows, I configured my session the same way I configured my Windows NT session (see Figure 5).

A Word of Caution

Be sure that the user has logon rights to the SNA Server machine. If you have several servers and don't use domain security, it is possible to have different passwords on every server. When I changed my password on my local PC, but not on the SNA Server PC, I again received the 546 error message. I changed my password on the SNA Server machine to be the same as my password on the Windows for Workgroups PC, and the problem went away. This problem is avoided with Windows NT because password validation is done at the domain server level; there is only one place to enter your password for the entire network. This kind of problem is associated with the way Windows for Workgroups handles security, not SNA Server.

Client Software Usage

The client software package provides two basic methods to access the gateway from a client machine. SNA Server's ROUTER.EXE program emulates the PC Support DOS router, allowing PC Support functions to be used from a gateway client. SNA Server also comes with a 5250 emulator applet that does not require loading any DOS Terminate and Stay Resident (TSR) programs. The SNA Server package provides coupons for discounts on third-party, Windows-based routers and emulators.

The 5250 emulator applet is designed for testing purposes only. However, it has some nice features. Scaleable fonts allow you to see the entire AS/400 screen when you resize the emulator window. You can specify whether you want a 24x80 or 27x132 display. The applet provides menu options for 5250 keys with no PC keyboard equivalents. Unfortunately, there is no macro recorder for recording keystrokes, and you can't run multiple sessions.

RAS Me from Afar

Windows NT and Windows For Workgroups are shipped with Remote Access Services (RAS). RAS is a utility that allows you to dial up to a RAS server on the network from your remote Windows PC and connect to any network server to which you have authority. Once you are connected (a simple matter of pointing and clicking), you become another node on the network, and you can use most of the services available to the local nodes, including SNA Server. If you install the SNA Server client software on the remote PC, you can bring up an emulation session just as if you were locally attached to the network. If you have NetSoft's NS/Router product, you can even run client/server applications that access the AS/400 database.

Caveat Emptor-Not!

Microsoft has recently announced Version 2.11 of SNA Server. Microsoft has added support for the PowerPC architecture, enabling customers to run SNA Server on new systems based on the PowerPC processors from IBM, Motorola, and others. The new version of SNA Server includes an ODBC/DRDA driver for Windows and Windows NT clients, enabling standard desktop applications that support Open Database Connectivity (ODBC), such as Microsoft Excel and Access, to connect to AS/400 database files. Microsoft added support for the Windows version of Client Access-giving customers AS/400 connectivity without the need for the Client Access router-and. 16-bit SNA applications running in the 32- bit Windows NT environment. Version 2.11 is scheduled to be available in the second quarter of 1995.

The version I installed provides a combination of easy graphical installation, good performance, excellent network environment support, and remote client access, SNA Server deserves serious consideration. It seems to be the LAN-to- AS/400 connectivity tool of the 90s. My only complaint is that the manuals failed to help me resolve the problem I had configuring the client and provided no trouble-shooting section, but CompuServe's support proved adequate for me. For users who don't have access to CompuServe, Microsoft provides support services like fax-back service called FastTips for common questions and pay- per-incident telephone support. Unfortunately, there is no free phone support.

SNA Server is much easier to install and configure than some of the other gateways I have used, and the technical features can't be beat. It provides a stable, robust solution for LAN-to-AS/400 connectivity. SNA Server is the solution of choice in our shop.

Brian Singleton is an AS/400 programmer/analyst. He can be reached through Midrange Computing or Internet E-mail at This email address is being protected from spambots. You need JavaScript enabled to view it..

References

Microsoft Corporation. Microsoft SNA Server: 3270/5250 Applet User's Guide. Redmond, Washington: Microsoft Corporation, 1994.

Microsoft SNA Server: Administration Guide. Redmond, Washington: Micro-soft Corporation, 1994.

Microsoft SNA Server: Managing Microsoft SNA Server. Redmond, Washington: Microsoft Corporation, 1994.

Microsoft SNA Server: Reference. Redmond, Washington: Microsoft Corporation, 1994.

Microsoft Press. Microsoft Windows NT Resource Kit. 4 vols. Redmond, Washington: Microsoft Corporation, 1995.


Implementing MS's SNA Server in the 400 Environmen

Figure 1 SNA Server Installation Process Overview

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Implementing MS's SNA Server in the 400 Environmen

Figure 2 Server Properties

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Implementing MS's SNA Server in the 400 Environmen

Figure 3 Connection Properties

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Implementing MS's SNA Server in the 400 Environmen

Figure 4 802.2 Setup

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Implementing MS's SNA Server in the 400 Environmen

Figure 5 Session Configuration

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Implementing MS's SNA Server in the 400 Environmen

Figure 6 Windows 3.x Setup Screen

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Brian Singleton
Brian Singleton is former editor of Midrange Computing. He has worked in the IBM midrange arena for many years, performing every job from backup operator to programmer to systems analyst to technology analyst for major corporations and IBM Business Partners. He also has an extensive background in the PC world. Brian also developed a line of bestselling Midrange Computing training videos, authored the bestselling i5/OS and Microsoft Office Integration Handbook, and has spoken at many popular seminars and conferences.

MC Press books written by Brian Singleton available now on the MC Press Bookstore.

i5/OS and Microsoft Office Integration Handbook i5/OS and Microsoft Office Integration Handbook
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