BUG: 16-bit RPC Problems with Novell's Client32 for Windows 95

• Microsoft Win32 Software Development Kit (SDK) for Windows 95, versions 3.51, 4.0

SYMPTOMS

If a 16-bit RPC application on Windows 95 uses SPX with the Client32 Netware Client from Novell, it may occasionally get RPC_CALL_FAILED errors (decimal 33) while making RPC calls to a server running on a Windows NT platform.

CAUSE

This error occurs on the return from the RPC call, when a large amount of data is being transferred. The packet size is negotiated incorrectly. As a result, when the size of the data to be transferred exceeds the underlying networks maximum frame size, the call fails.

The frame sizes are dependent on the network architecture. For example, Ethernet networks use a size of approximately 1500 bytes, while Token Ring networks use 4096 bytes.

RESOLUTION

As a workaround, programmers must ensure that the data they transfer does not exceed the MTU of any of the networks between the client and the server. For example, if a client on an Ethernet talks to a server on a Token Ring network, the data must be less than the Ethernet MTU per RPC call.

STATUS

Microsoft has confirmed this to be a bug in the Microsoft products listed at the beginning of this article. We are researching this bug and will post new information here in the Microsoft Knowledge Base as it becomes available.