Microsoft KB Archive/140007

= WFW Direct Hosting over ODI Drivers Drop Network Connections =

Article ID: 140007

Article Last Modified on 12/5/2003

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APPLIES TO


 * Microsoft Windows NT Workstation 3.5
 * Microsoft Windows NT Workstation 3.51
 * Microsoft Windows NT Server 3.5
 * Microsoft Windows NT Server 3.51
 * Microsoft Windows for Workgroups 3.11

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This article was previously published under Q140007



SUMMARY
A Windows for Workgroups 3.11 client, running IPX and connecting to an Windows NT version 3.5 or 3.51 Server or Workstation by default uses direct hosting. Direct hosting is a method of bypassing the NetBIOS layer and sending client/server messages (SMBs) directly over the transport, in this case, IPX.

If the Windows for Workgroups 3.11 client is using an Open Datalink Interface (ODI) driver rather than an NDIS driver, the client may drop packets from the server and lose the connection.

This is most evident where you have large file reads and a fast server.



MORE INFORMATION
You may be able to improve the connection reliability by not using direct hosting from client to server. This forces NetBIOS to manage the session, rather than making the redirector manage retransmissions. To turn direct hosting off at the client, add the following parameter to the [network] section of system.ini: directhost=no Note: Page 4-12 of the "Windows for Workgroups Resource Kit", Addendum for Version 3.11 incorrectly states this parameter as 'directhosting'. This is a documentation error.

Additionally, you must install the IPX/SPX Compatible Transport with NetBIOS on the Windows for Workgroups client.

When you turn direct hosting off, large file read requests from the client are requested in a read block raw SMB, and the data is transferred over the NetBIOS session. The following trace shows at frame 20, the client initiates a read block raw, and the data is returned by the server over the NetBIOS session: #   DeltaT  Src MAC     Dst MAC   Protocol Description

20  0.004   WFW Client  NT server   SMB     C read block raw, FID = 0x800, Read 0xfe00 at 21  0.147   NT server   WFW Client  NBIPX   Session Data 22  0.001   NT server   WFW Client  NBIPX   Session Data, Send Seq 0x0C, Offset 0x5AC 23  0.002   WFW Client  NT server   NBIPX   Session Data, Ack, Recv Seq 0x0D, 0x10 Bytes Received 24  0.002   NT server   WFW Client  NBIPX   Session Data 25  0.002   NT server   WFW Client  NBIPX   Session Data 26  0.001   NT server   WFW Client  NBIPX   Session Data, Send Seq 0x0F, Offset 0x16B0 27  0.002   WFW Client  NT server   NBIPX   Session Data, Ack, Recv Seq 0x10, 0x13 Bytes Received If direct hosting is on, then the redirector initiates a read block multiplex, and the data is sent back in read block multiplex response SMBs, directly over IPX. The following trace shows a read block multiplex coming from the client at frame 19. Frames 20 through 29 show the server responding with read block multiplex responses, and frame 30 is another read block multiplex command from the client: #   DeltaT  Src MAC     Dst MAC   Protocol Description

19  0.005   WFW Client  NT server    SMB   C read block mpx, FID = 0x800, Read 0x3750 at 0x00000000 20  0.003   NT server   WFW Client   SMB   R read block mpx, Read 0x588 of                                               0x3750 21  0.006   NT server   WFW Client   SMB   R read block mpx, Read 0x588 of                                               0x3750 22  0.001   NT server   WFW Client   SMB   R read block mpx, Read 0x588 of                                               0x3750 23  0.002   NT server   WFW Client   SMB   R read block mpx, Read 0x588 of                                               0x3750 24  0.002   NT server   WFW Client   SMB   R read block mpx, Read 0x588 of                                               0x3750 25  0.001   NT server   WFW Client   SMB   R read block mpx, Read 0x588 of                                               0x3750 26  0.001   NT server   WFW Client   SMB   R read block mpx, Read 0x588 of                                               0x3750 27  0.002   NT server   WFW Client   SMB   R read block mpx, Read 0x588 of                                               0x3750 28  0.001   NT server   WFW Client   SMB   R read block mpx, Read 0x588 of                                               0x3750 29  0.001   NT server   WFW Client   SMB   R read block mpx, Read 0x588 of                                               0x3750 30  0.004   WFW Client  NT server    SMB   C read block mpx, FID = 0x800, Read 0x3750 at 0x00003750 In this case, the redirector is responsible for requesting resends of lost packets in either direction. This may be too much of a burden on the Windows for Workgroups redirector which is running over an ODI driver. The extra layer needed to map NDIS 3.0 protocols to an ODI NIC driver (MSODISUP.386) may also contribute to the problem, as running direct hosting over NDIS drivers does not seem to exhibit this problem.

Additional query words: prodnt 3.11 3.50 3.51 directhost directhosting

Keywords: KB140007

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