Microsoft KB Archive/308927

= CNOS Negotiation May Fail with &quot;Modename not recognized&quot; Error =

Article ID: 308927

Article Last Modified on 2/22/2007

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APPLIES TO


 * Microsoft SNA Server 4.0
 * Microsoft SNA Server 4.0 Service Pack 1
 * Microsoft SNA Server 4.0 Service Pack 2
 * Microsoft SNA Server 4.0 Service Pack 3
 * Microsoft SNA Server 4.0 Service Pack 4
 * Microsoft Host Integration Server 2000 Standard Edition

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This article was previously published under Q308927



SYMPTOMS
An Advanced Program-to-Program Communications (APPC) or Common Programming Interface for Communications (CPI-C) application may fail to establish a session even if it is using the correct session settings (such as Local APPC LU, Remote APPC LU, or Mode).



CAUSE
Establishing an APPC session requires a successful Change Number of Sessions (CNOS) negotiation. When a CNOS negotiation fails for a LU-LU- mode triplet, the host sends a CNOS reply with the reply modifier field set to indicate the problem that has been encountered. However, when SNA Server submits a subsequent CNOS request, it does not clear the reply modifier field. This may cause the CNOS to fail even if the correct LU-LU-mode triplet was used.



SNA Server 4.0
A supported fix is now available from Microsoft, but it is only intended to correct the problem that is described in this article. Apply it only to computers that are experiencing this specific problem. This fix may receive additional testing. Therefore, if you are not severely affected by this problem, Microsoft recommends that you wait for the next SNA Server version 4.0 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Product Support Services to obtain the fix. For a complete list of Microsoft Product Support Services phone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/default.aspx?scid=fh;EN-US;CNTACTMS

NOTE: In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The typical support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

The English version of this hotfix has the file attributes (or later) that are listed in the following table. The dates and times for these files are listed in coordinated universal time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time tool in Control Panel.

NOTE: Because of file dependencies, the most recent fix that contains the preceding files may also contain additional files.

Host Integration Server 2000
To resolve this problem, obtain the latest service pack for Host Integration Server 2000. For additional information, click the following article number to view the article in the Microsoft Knowledge Base:

328152 How to Obtain the Latest Host Integration Server 2000 Service Pack

The English version of this fix should have the following file attributes or later:

NOTE: Because of file dependencies, the most recent fix that contains the preceding files may also contain additional files.



SNA Server 4.0
Microsoft has confirmed that this is a problem in SNA Server versions 4.0, 4.0 SP1, 4.0 SP2, 4.0 SP3, and 4.0 SP4.

Host Integration Server 2000
Microsoft has confirmed that this is a problem in Host Integration Server 2000. This problem was first corrected in Host Integration Server 2000 Service Pack 1.



MORE INFORMATION
If SNA Server Data Link Control (DLC) message tracing is enabled, the resulting trace may appear as follows: 01020201->0C160000 DLC DATA DAF:7D OAF:04 ODAI:on Normal RQE FMD FI MC DR1

Header at address 0138618C, 1 elements 0B01000C 10112E00 7D040002 01006601    <........}.....f.>

Element at address 01D7E428, start 10, end 25 0890000D 0502FF00 03D00000 0206F100    <..............1.> The ATTACH is sent out against the CNOS TP 0x'06F1', as follows: --- 06:57:04.0151 01020201->0C160000 DLC DATA DAF:7D OAF:04 ODAI:on Normal RQE FMD EC DR1 CD

Header at address 01393B18, 1 elements 07058C00 10112E00 7D040003 0100CB00    <........}.......>

Element at address 01DC2FB8, start 10, end 37 01902000 19121002 02000000 00340032    <.. ..........4.2>               ^^ ^^ 00020008 D4F6F2D7 F0F0F240              <....M62P002@    > A CNOS is sent to the host using the correct mode name, as follows: --- 06:57:04.0245 0C160000->01020201 DLC DATA DAF:04 OAF:7D ODAI:on Normal RQE FMD BC EC DR1 PI CEB

Header at address 01397F8C, 1 elements 07058C00 10112E00 047D0001 01006601    <.........}....f.>

Element at address 01D9C7C8, start 10, end 37 03910100 19121008 02000000 00340032    <.j...........4.2> ^^ ^^ 00020008 D4F6F2D7 F0F0F240             <....M62P002@    > but is failing with 0802 (indicated above with ^^^^).

However, when you look at the CNOS request in the previous frame, you can see that the reply modifier field is set to X'02' (indicated by ^^^^), or &quot;abnormal--mode name not recognized&quot;, showing that a previous CNOS request failed.

According to the IBM SNA Formats (GA27-3136) guide, reserved fields such as the reply modifier should be set to 0x'00'.

Future levels of the protocol may use reserved fields and will depend on back-level implementations. It is important for the sender to set reserved fields to zero.

Additional query words: CNOS reply modifier HIS 2000

Keywords: kbbug kbfix kbhostintegserv2000presp1fix kbhostintegserv2000sp1fix KB308927

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