Microsoft KB Archive/166762

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PRB: Winsock 1.1 Send Over IPX/SPX Fails With WSAECONNRESET

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Q166762

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The information in this article applies to:


 * Microsoft Win32 Application Programming Interface (API), used with:
 * Microsoft Windows 95
 * Microsoft Windows 95 OEM Service Release, version 2.0

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SYMPTOMS
Winsock 1.1 IPX/SPX applications communicating with NetWare applications or special devices using the send API can fail with error WSAECONNRESET. This occurs when a Winsock application attempts to send large buffers using the SOCK_SEQPACKET socket type to a Netware IPX application or special device.

CAUSE
Microsoft's implementation of the IPX/SPX protocol takes advantage of a network's full media size and does not limit its data packet transmission size to 576 bytes. Some Netware applications or devices cannot handle data packet transmissions greater than 576 bytes. The limitation is an artificial one that IPX applications inherited from the Xerox Network System's (XNS) Internet Datagram Protocol (IDP) packet structure which originally limited IPX packets to 576 bytes (IPX header plus data). Some NetWare specific IPX/SPX applications enforce the limitation on themselves by inclusion of a constant MaxIPXPacketSize from header files in the NetWare SDK.

RESOLUTION
If your Winsock 1.1 application must communicate with an application that imposes the artificial packet limit, you can do so by creating the socket with type SOCK_STREAM and limiting the size of your send calls to 534 or fewer bytes.

STATUS
This behavior is by design.

MORE INFORMATION
The Novell IPX Router Specification states "While IPX implementations must be able to handle at least a 576 byte packet, enhancements to IPX now allow support for packet sizes up to 65,535 bytes."