Host Connectivity and Windows 98

Host connectivity in this section refers to connecting to legacy IBM System 370/390-compatible mainframe computers, the mid-range IBM AS/400 computers, DEC VAX/VMS, UNIX, and HP 3000 computers. Host terminal emulation applications running in Windows 98 require network protocols to connect to their respective hosts.

The common network protocols used to support host connectivity include the following:

• IPX/SPX. The IPX/SPX-compatible transport provided with Windows 98 is compatible with Novell NetWare IPX/SPX, and can be installed to support host connectivity using terminal emulation programs and gateways supporting an IPX/SPX interface.
• NetBEUI. The NetBEUI protocol provided with Windows 98 supports a NetBIOS programming interface and conforms to the IBM NetBEUI specifications. It also includes performance enhancements related to NetBIOS 3.0. Microsoft NetBEUI can be installed on computers running Windows 98 to provide NetBIOS support for host connectivity using terminal emulation programs and gateways supporting a NetBIOS interface.
• TCP/IP. The TCP/IP protocol provided with Windows 98 is a complete implementation of the most common and accepted protocol available. It allows connectivity between interconnected networks with different operating systems and hardware architectures, such as UNIX, IBM mainframes, and Microsoft networks. Usually, host connectivity with the TCP/IP protocol is provided using Telnet services, such as TN3270 connecting to legacy mainframes, TN5250 connecting to an IBM AS/400, and using gateways supporting a TCP/IP interface. Microsoft TCP/IP supports the Windows Sockets 2.0 interface.
• Data Link Control (DLC). Windows 98 includes both a protected-mode DLC driver (Dlc.vxd), which supports 32-bit and 16-bit DLC applications, and a real-mode DLC driver (Msdlc.exe), which supports only 16-bit applications. It is used primarily to access IBM mainframe computers and Hewlett-Packard network-ready printers. Microsoft recommends that you use the protected-mode driver in most cases. However, some 16-bit DLC applications will work only with the real-mode DLC driver. For more information about applications that require the 16-bit DLC, see "Using 32-bit DLC for Connectivity" in Chapter 15, "Network Adapters and Protocols."

This section provides tips for using TCP/IP, terminal emulation applications, and gateways for connectivity.

For information about using Microsoft TCP/IP, Microsoft NetBEUI, the IPX/SPX-compatible protocol, and Microsoft DLC, see Chapter 15, "Network Adapters and Protocols."

Using TCP/IP for Host Connectivity

Many utilities and terminal emulation programs from other vendors allow direct communication with a mainframe or host computer using a TCP/IP protocol stack. The protected-mode version of Microsoft TCP/IP included with Windows 98 relies on the Windows Sockets version 1.1 or 2.0 interface. Any terminal emulation program or utility that you use to connect to a mainframe or host computer over Microsoft TCP/IP must support Windows Sockets 1.1 or 2.0. If the application does not support Windows Sockets 1.1 or 2.0, contact the application vendor to obtain a version that does; otherwise, do not use Microsoft TCP/IP.

If you want to connect to a host computer using Telnet or TCP/IP and you are running an application that emulates an IBM 3270 or 5250, or a DEC VT xx computer terminal, you can use Microsoft TCP/IP.

Some third-party TCP/IP stacks cannot be installed after Windows 98 Setup due to conflicts with Windows Sockets 2.0, which is installed with Microsoft TCP/IP. If you want to use a third-party TCP/IP stack with Windows 98, you should install it before running Windows 98 Setup. In almost all cases, this ensures that your third-party stack is successfully upgraded. If you do not do install the stack before running Setup, you can try restoring Windows Sockets 1.1, then installing the third-party TCP/IP stack. However, this method does not always work, and Microsoft does not support it. Also, if you restore Windows Sockets 1.1, you will not be able to use features, such as Quality of Service. For more information, see Chapter 15, "Network Adapters and Protocols."

To restore Windows Sockets 1.1

1. In Control Panel, double-click Add/Remove Programs.
2. On the Install/Uninstall tab, click Restore Winsock 1.1 Configuration, and then click Add/Remove.
3. When asked whether you want to restore your original configuration, click Yes.

Note

Microsoft does not support using 16-bit TCP/IP stacks.

If your emulation software requires a TSR to communicate with another vendor’s TCP/IP protocol stack, you must remove the TSR and reconfigure the emulation software for Windows Sockets in order to communicate using Microsoft TCP/IP in Windows 98. To determine the proper configuration with Windows Sockets, see the documentation for the emulation software.

For more information about TCP/IP, see Chapter 15, "Network Adapters and Protocols."

Using Terminal Emulation Applications

Terminal emulation applications offer several different connectivity options for connecting to an IBM System 370/390-compatible mainframe host, IBM AS/400, or DEC VAX computer. This section describes configuration and other issues related to using terminal emulation programs.

Connecting to a NetWare for SAA gateway.

For most 32-bit terminal emulation applications, configuring Windows 98 with the Microsoft IPX/SPX-compatible protocol enables connectivity to a NetWare for SAA gateway or to any gateway supporting IPX/SPX connectivity. If you are using a token-ring network with source routing, use the Network option in Control Panel to make sure that Microsoft IPX/SPX-compatible protocol appears in the list of network components. In Advanced properties for the protocol, set the Source Routing property to a 16-entry cache size.

Connecting to a Windows NT SNA 2.0 or later server.

Windows 3.x client software supports connectivity to a Windows NT SNA 2.0 or 2.1 server. The Windows NT 32-bit client for SNA should not be used; it was designed to work only with client computers running Windows NT Workstation.

Connecting to an IBM AS/400 with IBM PC Support software.

You can use Windows 98 to connect to an AS/400 using the IBM PC Support software. To do so, configure the PC Support application for Basic Mode; do not use Extended Mode. If the PC Support application was configured to connect using DLC, make sure that Microsoft DLC or IBM Lan Support is already installed on the computer.

You can also use Windows 98 to connect to an AS/400 using the NetWare for SAA gateway and the IBM PC Support application. Configure the PC Support application for Basic Mode; do not use Extended Mode. The IBM-supplied Dos16m.386 file is not compatible with Windows 98.

If Windows 98 is configured to use the IPX/SPX-compatible protocol, then you must create a Winstart.bat batch file in the \Windows directory and add entries in this file to run Pcswin.com and Strnrtr.exe (the Novell-compatible router). If you encounter problems using the protected-mode IPX/SPX-compatible transport with the Novell-compatible PC Support router, then configure Windows 98 to use the Novell-supplied NETX or VLM client with IPXODI, as described in "Configuring Network Adapter Drivers for Real-Mode Novell Clients" earlier in this chapter.

For information about using TCP/IP with IBM 3270 terminal emulation, see "Using TCP/IP for Host Connectivity" earlier in this chapter.

Using Gateways for Connectivity

When your network uses a gateway to communicate with a host computer, the client computer running Windows 98 communicates with the gateway computer just as it does with any other computer on the network. The gateway computer translates requests from the client into a form that can be understood by the host, then communicates with the host, and returns the information to the client. In this configuration, the client computer can connect to the gateway using any protocol that the gateway supports. The gateway uses some form of the DLC protocol to communicate with the host.

Table 17.23 shows commonly used gateways and the supported operating systems.

Table 17.23 Commonly used gateways and supported operating systems

Many of the gateways in the preceding table have MS-DOS versions, which run only under MS-DOS, not under Windows. Windows 98 does not support running the MS-DOS-based gateways in a VM. For information about support for a particular gateway under Windows 98, contact your gateway vendor.