You have a computer that is running Microsoft Host Integration Server 2004.
This computer uses the IP-DLC link service to communicate with an IBM mainframe.
In this scenario, the IP-DLC link service may send a NOTIFY Request Unit (NOTIFY RU) to an IBM mainframe before it sends the ACTLU +RSP Response Unit (ACTLU +RSP RU) to the mainframe. This action is a violation of the IBM SNA protocol that is used when dependent logical units (LUs) such as 3270 LUs are available to be used.
Note This issue also applies to Microsoft Host Integration Server 2006.
Host Integration Server 2006
To resolve this problem, obtain the latest service pack for Host Integration Server 2006. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
979497 How to obtain the latest Host Integration Server 2006 service pack
Host Integration Server 2004
A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.
If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.
Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft Web site:
Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.
You must have Microsoft Host Integration Server 2004 installed to apply this hotfix.
You must restart the Host Integration Server computer after you install this hotfix.
Hotfix replacement information
This hotfix does not replace any other hotfixes.
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 hotfix that contains these files may also contain additional files.
Microsoft Host Integration Server 2004 SP1
A hotfix is currently not available for Microsoft Host Integration Server 2004 SP1.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
After you apply this update, the IP-DLC link service correctly sends the ACTLU +RSP RU before it sends the NOTIFY RU to the IBM mainframe.
The following excerpt from an IP-DLC link service message trace shows the NOTIFY RU being sent to the IBM mainframe before the ACTLU +RSP RU. The traces were captured by using the SNA Trace utility (Snatrace.exe) to enable the Data Link Control and Level 2 Messages trace options for the SNAIP1 link service on a Host Integration Server computer.
The Data Link Control message trace shows the ACTLU +RSP RU and the NOTIFY RU in the following order:
DLC 03020101->01160001 DLC DATA DLC DAF:00 OAF:02 ODAI:off Exp. DLC ACTLU +RSP SC FI BC EC DR1 DLC DLC ---- Header at address 010142E0, 1 elements ----DLC 04010007 10002D00 00028E4B 0100041D <......-....K....>DLC DLC ---- Element at address 01A026D0, start 10, end 28 ----DLC EB80000D 02010085 8000000C 06010001 <.......e........>DLC 000000 <... >DLC 03020101->01160001 DLC DATA DLC DAF:00 OAF:02 ODAI:off Normal DLC NOTIFY RQD FMD FI BC EC DR1 DLC DLC ---- Header at address 01014244, 1 elements ----DLC 02020000 00002C00 00020000 0100041D <......,.........>DLC DLC ---- Element at address 01A04230, start 10, end 23 ----DLC 0B800081 06200C06 01000100 0000 <...a. ........ >
The Level 2 Messages section of the traces has the ACTLU +RSP RU and the NOTIFY RU in the following order. This is the order in which they are sent to the IBM mainframe. The following data includes the NOTIFY RU:
You can use a network trace utility such as Network Monitor to capture the data that is sent between the Host Integration Server computer and the IBM mainframe to confirm that the order of the ACTLU +RSP RU and the NOTIFY RU is as shown in this trace data.
The following table shows the expected SNA data flow that occurs when a dependent LU, such as a 3270 display LU, is available to be used.
Host Integration Server
Direction of SNA Data Flow
When a user tries to make a 3270 session available to be used, the data flow continues as follows.
At this point, the 3270 session is available to be used, and the user typically receives a VTAM USSMSG 10 sign-on screen or another application screen.
For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base:
824684Description of the standard terminology that is used to describe Microsoft software updates