Microsoft KB Archive/174202

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Configuring SPX Watchdog Timers in Windows 95


The information in this article applies to:

  • Microsoft Windows 95
  • Microsoft Windows 95 OEM Service Release, version 2.0


Programs using the IPX/SPX-compatible protocol (NWLINK) to communicate over a wide area network (WAN) or other slow link may not connect or may experience dropped connections. Analysis of network traffic may reveal that an SPX Watchdog timer has expired on the remote node. This symptom can occur particularly if the watchdog parameters on the server are configured to non-default values.


SPX Watchdog timers are not configurable for the IPX/SPX-compatible protocol in Windows 95 and Windows 95 OEM Service Release 2 (OSR2).


You may be able to work around this issue by reconfiguring the SPX watchdog timer parameters on the server to their default values.

This issue is resolved by the following updated file for Windows 95 and OSR2, and later versions of this file:

   NWLINK.VXD  version 4.00.1113  dated 6/6/97  51,567 bytes 


Microsoft has confirmed this to be a problem in Microsoft Windows 95 and OEM Service Release 2 (OSR2). An update to address this problem is now available, but is not fully regression tested and should be applied only to computers experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft does not recommend implementing this update at this time. Contact Microsoft Technical Support for additional information about the availability of this update.

This issue is resolved in Microsoft Windows 98.


According to Novell documentation (TID #2910905), the following timers are among the Watchdog timers that are configurable for Novell's IPX/SPX protocol:

SPX Verify Timeout

This parameter controls how long the watchdog waits after it has sent a packet before it sends a system packet to keep the connection alive.

SPX Listen Timeout

This parameter controls how long the watchdog waits after it has received a packet before it sends a system packet requesting an acknowledgement so it will know the connection still exists.

Send Timeout

This parameter controls how long IPX waits for an acknowledgement of a sent packet.

For additional information about Novell's implementation of SPX timers, please consult Novell or your Novell NetWare documentation.

For additional information about issues resolved by updates to this component, please see the following article in the Microsoft Knowledge Base:

Q166321 Configuring Maximum IPX Packet Size in Windows 95

Q164474 OE Exception in NWLINK Sending Message from Microsoft Exchange

Q159959 Connection Fails Over IPX with Duplicate SPX Connection ID

Q145651 Windows Sockets Program Generates Errors In WSIPX

Q149448 Incorrect Node Address In IPX Header Causes Broadcast Storm

Q138000 Error Connecting to an Attachmate Gateway with a Cisco Router

For additional information about Windows 95 updates, please see the following article in the Microsoft Knowledge Base:

Q161020 Implementing Windows 95 Updates

Keywords : kbnetwork osr1 osr2 win95
Issue type : kbprb
Technology : kbWin95search kbOPKSearch kbWin95

Last Reviewed: June 13, 2001
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