A Windows Networking API set was introduced in Windows 3.0 and enhanced in Windows 3.1. The Windows 3.1 WinNet Interface is set of network independent APIs where a network vendor supplies a DLL which implements the interface, and Windows will interact with exactly one such DLL (WinNet16 driver) to extend itself to be network aware. With a couple of exceptions, applications are not allowed use these APIs. The APIs are relatively high level, often requiring the NP DLL to bring up dialogs to perform operation resulting in a variety of UIs for the some functionality.
In LAN Manager 2.1, a layer was placed above the Windows 3.1 WinNet Interface (the multi-net DLL) which was used to allow the client to simultaneously access NetWare and LAN Manager networks by routing requests to the appropriate networks.
In Windows for Workgroups 3.1 the common network dialogs were modified to use the WinNet Interface rather than be network specific, an additional API set was added so that specific networks could be targeted via these dialogs (the multi-net APIs), and the dialogs supported an arbitrary second network. Installation and setup was extended to support a secondary network.
In Windows/NT the multi-net layer was formalized to be the MPR and the API set was expanded to provide network browsing capability using Win32 interfaces, and to allow for some differences between networks (different naming conventions, and the NetWare server security model).
In Windows 95, the main goals of the MPR design are: allow the user seamless access to several networks at a time, and to expose a set of networking APIs callable by applications. This set, together with the other Win32 APIs should be able to provide all the commonly used capabilities required by applications.
To summarize the goals new to Windows 95:
Support for the Win32 WinNet APIs as defined in Windows NT.
Provide an interface that allows seamless browsing of network resources into authenticated information (network directories, printers, and other network resources). This includes consistent handling of authentication requirements across multiple networks.
Backward compatibility with Window for Workgroups 3.11, namely to support at most one Windows 3.1 architecture network (i.e., a network which uses a Windows 3.1 WinNet16 DLL, and the file system is not implemented as a network IFS).