KB166875 - 5250 Emulator Won't Connect Even Though Sessions Are Available

Article ID: 166875

Article Last Modified on 2/20/2004

Microsoft SNA Server 3.0
Microsoft SNA Server 3.0 Service Pack 4

This article was previously published under Q166875

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SYMPTOMS

When connecting to an AS/400, the 5250 applet shows Not Connected in the lower left corner. SNA Server shows that there are sessions available for the LU-LU pair the 5250 applet is attempting to use. However, some of these LUs on the AS/400 are in an Active - Detached state, thereby preventing the request for conversation from succeeding. The same thing will happen with other 5250 emulators. However, the message displayed in the emulator may be different.

NOTE: There are various situations in which you might see a Not Connected 5250 status. This article documents one possible situation. For other possible situations, see the following Microsoft Knowledge Base article:

150796 5250 Emulator Displays a BlackScreen Then Disconnects

CAUSE

The exact cause of why the AS/400 sometimes shows sessions in an Active - Detached state is unknown.

WORKAROUND

To work around this problem, apply the fix referenced below, and then edit the registry as follows.

NOTE: You must first apply the fix referenced below before editing the registry.

WARNING: Using Registry Editor incorrectly can cause serious, system-wide problems that may require you to reinstall Windows NT to correct them. Microsoft cannot guarantee that any problems resulting from the use of Registry Editor can be solved. Use this tool at your own risk.

Start Registry Editor (Regedt32.exe or Regedit.exe, as appropriate for your version of Windows NT).

Go to the following key in the registry:

HKEY_LOCAL_ MACHINE\SYSTEM\CurrentControlSet\Services\SnaServr\ 
   Parameters

On the Edit menu, click Add Value and use the following entry:
Value Name: SessionLimitMargin Data Type: REG_SZ
This registry entry artificially lowers the number of post cnos negotiation by the value specified. Therefore, if the negotiated session limit for an LU-LU-MODE triplet is 8 and SessionLimitMargin is 2, the SNA Server service node will only start 6 sessions on the triplet.
Exit Registry Editor.

This will work around the problem where SNA Server thinks it has sessions available and the AS/400 does not.

STATUS

Microsoft has confirmed this to be a problem in SNA Server versions 2.11 and 3.0. This problem was corrected in the latest SNA Server version 3.0 U.S. Service Pack. For information on obtaining this Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K

MORE INFORMATION

The following will be seen in an SNA Server DLC trace:

The SNA Server service, thinking it has sessions available for a conversation request, sends an Attach (02ff) for conversation to the AS/400:

   DLC    ---------------------------------------------- 22:00:54.97
   DLC    01020601->04160005 DLC DATA
   DLC                       DAF:36 OAF:01 ODAI:off Normal
   DLC                       RQE FMD FI BC EC DR1 PI CD
   DLC
   DLC    ---- Header  at address 00CC45EC, 1 elements ----
   DLC    0B05537E 324F2C00 36010001 01001121     <..S~2O,.6......!>
   DLC
   DLC    ---- Element at address 011C68C8, start 10, end 233 ----
   DLC    0B91203F 0502FF18 03D00040 0430F0F0     <.j ?.......@.000>
   DLC    F50F0402 D7C3E209 014AB1D6 5ACABB72     <5...PCS..J.OZ..r>
   DLC    8A160DC1 D7D7D54B D4E2E2D5 C1E2F1F6     <...APPNKMSSNAS16>
   DLC    54310016 0A040001 00080000 00000000     <T1..............>
   DLC    0001009E 12F5009A 12E20096 12A02000     <.....5...S.o.. .>
   DLC    05100100 000023D9 E8C1D5C1 D7D7C1F1     <......#RYANAPPA1>
   DLC    40F3F1F9 F74040C3 F2404040 40000000     <@3197@@C2@@@@...>
   DLC    00000000 00000000 000026C4 E4E2C200     <..........&DUSB.>
   DLC    F6F9F740 F0F3F740 40404040 40404040     <697@037@@@@@@@@@>
   DLC    40404040 40404040 40E7F900 00000000     <@@@@@@@@@X9.....>
   DLC    41C10000 00004040 40404040 4040D7C3     <AA....@@@@@@@@PC>
   DLC    E2404040 40404040 D7C3E240 40404040     <S@@@@@@@PCS@@@@@>
   DLC    40402040 40404040 40404040 40404040     <@@ @@@@@@@@@@@@@>
   DLC    40404040 40404040 40404040 40404040     <@@@@@@@@@@@@@@@@>

The AS/400 rejects the Attach with a 0846 0000 sense code promising the SNA Server the real error in a following message:

   DLC    ---------------------------------------------- 22:00:56.66
   DLC    04160005->01020601 DLC DATA
   DLC                       DAF:01 OAF:36 ODAI:off Normal
   DLC                       -RSP FMD SD BC EC DR1
   DLC
   DLC    ---- Header  at address 00CC6AE4, 1 elements ----
   DLC    0B05537E 324F2C00 01368000 0100BB00     <..S~2O,..6......>
   DLC
   DLC    ---- Element at address 011C68C8, start 10, end 16 ----
   DLC    87900008 460000                         <g...F..         >

Here is the actual error from the AS/400:

   DLC    ---------------------------------------------- 22:00:56.87
   DLC    04160005->01020601 DLC DATA
   DLC                       DAF:01 OAF:36 ODAI:off Normal
   DLC                       RQE FMD FI BC EC DR1 PI CEB
   DLC
   DLC    ---- Header  at address 00CC5FEC, 1 elements ----
   DLC    0B05537E 324F2C00 01360001 0100BB00     <..S~2O,..6......>
   DLC
   DLC    ---- Element at address 011C5440, start 10, end 19 ----
   DLC    0B910107 07084B60 3100                  <.j....K`1.      >

   Primary Sense:   084B - Requested Resources Not Available
   Secondary Sense: 6031 - Transaction Program Not Available - Retry
   Available.

See SNA Formats Guide for the full text message.

The third-party products discussed here are manufactured by vendors independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability.

Keywords: kbbug kbfix kbnetwork KB166875