Microsoft KB Archive/162592

= SLI Libraries Set Wrong RU Size After Unbind(Hold) =

Article ID: 162592

Article Last Modified on 11/19/2003

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APPLIES TO


 * Microsoft SNA Server 3.0
 * Microsoft SNA Server 2.11 Service Pack 1
 * Microsoft SNA Server 3.0 Service Pack 4

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This article was previously published under Q162592





SYMPTOMS
Some 32-bit SLI applications may fail when you try to transfer large amounts of data. Investigation shows that the SNA RUI layer is returning an error code of DATA_TRUNCATED when performing a RUI_READ of more than 256 bytes.



CAUSE
There is a problem the SLI library such that it is not picking up the RU size correctly on successive BINDs. When the SLI library receives a BIND, followed by UNBIND(HOLD) and then a new BIND, the SLI library posts an RUI_READ of 256 bytes, even though 3840 byte RUs were negotiated in the final BIND.

So, when an RU arrives on the session which is larger than 256 bytes, the SLI_RECEIVE posted only receives 256 bytes and gets a DATA_TRUCATED error from the underlying RUI libraries and the SLI application only gets the first 256 bytes of the host application message.

Following is an illustration of the data flow involved: SNA Server             Host --

<--- BIND ("NMP" session manager), SLU receive size = "85"(256)

BIND +RSP --->

<-- UNBIND(Hold)

UNBIND +RSP -->

<--- BIND (Host SLI application), SLU receive size = "F8" (3840)

BIND +RSP -->





RESOLUTION
Apply the update to SNA Server 2.11 Service Pack 1 and SNA Server 3.0 that corrects this problem. The updated module is Winsli32.dll.

VTAM programmers will be able to work around this problem by configuring their session manager (NMP) to send a BIND to SNA Server that specifies a PLU send size of "F8" (this is set in Byte 11 of the BIND message).

NOTE: This is NOT the BTU size, but MAXDATA if configured in the LU definition or RUSIZE if configured in the MODETAB for the LU-LU session (or the NMP host session manager application).



STATUS
Microsoft has confirmed this to be a problem in the Microsoft products listed at the beginning of this article. A supported fix is now available, but has not been fully regression-tested and should be applied only to systems experiencing this specific problem. Unless you are severely impacted by this specific problem, Microsoft recommends that you wait for the next Service Pack that contains this fix. Contact Microsoft Technical Support for more information.



MORE INFORMATION
The following is an LUA API trace of a large RUI_READ demonstrating the failure.  SLI   -- 11:28:10.32 SLI   SLI_RECEIVE request SLI    Verb Parameter Block at address 0080FD68

Data omitted for brevity. In the VCB an lua_max_length of 4K assigned. NOTE: VCB structure is packed.

SLI SLI   -- 11:28:10.61 SLI   SLI_RECEIVE response SLI   IN_PROGRESS - OK SLI     Verb Parameter Block at address 0080FD68

Data omitted for brevity.

SLI RUI   -- 11:28:12.73 RUI   RUI_READ response RUI   UNSUCCESSFUL - DATA_TRUNCATED

Data omitted for brevity. In the VCB the lua_max_length(offset 35(2 byte field)) and lua_data_length(offset 37(2 byte field)) fields have a value of 256 bytes.

RUI

Additional query words: prodsna

Keywords: kbnetwork KB162592

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