Q195170: SNA Server Sends an Incorrect Sequence Number in BIND Response
Article: Q195170
Product(s): Microsoft SNA Server
Version(s): 3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1
Operating System(s):
Keyword(s):
Last Modified: 25-OCT-2001
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The information in this article applies to:
- Microsoft SNA Server, versions 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 4.0, 4.0 SP1
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SYMPTOMS
========
A previously functioning logical unit (LU) may remain pending even if no one
else is using it at the moment. On the host, this LU is shown as active.
CAUSE
=====
If an SNA Server sends an OPEN PLU Request to an application, it may send a BIND
-RSP with an incorrect sequence number to the host if it receives a lost
locality from the dynamic address module (DMOD) indicating that the application
has unexpectedly terminated, or that the network connection to the client
running the application has been lost.
The host ignores this response and keeps the LU active, waiting for the correct
BIND response and thus preventing this LU from being used.
RESOLUTION
==========
SNA Server 3.0
--------------
To resolve this problem, obtain the latest service pack for SNA Server version
3.0. For additional information, please see the following article in the
Microsoft Knowledge Base:
Q184307 How to Obtain the Latest SNA Server Version 3.0 Service Pack
SNA Server 4.0
--------------
This problem was corrected in the latest SNA Server version 4.0 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
STATUS
======
Microsoft has confirmed this to be a problem in Microsoft SNA Server version
3.0, 3.0 Service Pack 1, 3.0 Service Pack 2, 3.0 Service Pack 3, 4.0, and 4.0
Service Pack 1. This problem was first corrected in SNA Server 3.0 Service Pack
4.
MORE INFORMATION
================
If SNA Server Data Link Control (DLC) and 3270 message tracing is enabled, the
resulting trace may appear as follows:
A BIND request arrives from the host:
DLC ------------------------------------------------------------------
---
DLC 04160080->01020401 DLC DATA
DLC DAF:02 OAF:01 ODAI:off Exp.
DLC BIND RQD SC FI BC EC DR1
DLC
DLC ---- Header at address 0145965C, 1 elements ----
DLC 04000004 10112D00 02019586 0100EB00 <......-...nf....>
DLC
DLC ---- Element at address 0197322C, start 10, end 58 ----
DLC 6B800031 010303B1 90308000 05858785 <k..1.....0...ege>
DLC 00028000 00000018 5018507F 000007C1 <........P.P<7F>...A>
DLC D5F6F3D5 D4E30000 08E3E4F6 F3C7F3F0 <N63NMT...TU63G30>
DLC F0 <0 >
The Node (SNA Server service) sends an OPEN PLU to the application:
FMI -------------------------------------------------------
FMI 01022E06->A9120000 OPEN PLU REQUEST
FMI FMI CredR:5 CredS:1
FMI
FMI ---- Header at address 0145FFC8, 2 elements ----
FMI 01020202 01000005 00010000 0100EB00 <................>
FMI
FMI ---- Element at address 0196206C, start 1, end 28 ----
FMI 0B001154 55363347 33304C55 412D5255 <...TU63G30LUA-RU>
FMI 49202020 00050100 04000000 <I ........ >
FMI
FMI ---- Element at address 0197322C, start 4, end 58 ----
FMI 2D000201 95866B80 00310103 03B19030 <-...nfk..1.....0>
FMI 80000585 87850002 80000000 00185018 <...ege........P.>
FMI 507F0000 07C1D5F6 F3D5D4E3 000008E3 <P<7F>...AN63NMT...T>
FMI E4F6F3C7 F3F0F0 <U63G300 >
In this situation, the application connection was broken, or the application
itself was ended for some reason. This results in a Lost Locality to the SNA
Server's Node.
Because SNA Server knows that a BIND RSP is outstanding, it must generate and
send a -VE BIND RSP to the host.
DLC ------------------------------------------------------------------
---
DLC 01020401->04160080 DLC DATA
DLC DAF:01 OAF:02 ODAI:off Exp.
DLC BIND -RSP SC FI SD BC EC DR1
DLC
DLC ---- Header at address 01460064, 1 elements ----
DLC 00000000 00002D00 010211FC 01000200 <......-.........>
DLC
DLC ---- Element at address 01958794, start 10, end 17 ----
DLC EF900008 45000031 <....E..1 >
DLC ------------------------------------------------------------------
---
But instead of sending the response with sequence number 9586 as seen in the
request's transmission header, SNA Server sends the response with an incorrectly
calculated sequence number of 11FC.
Because the host gets a bad sequence number on the BIND RSP, it ignores the
response, and continues to wait for a BIND RSP on that LU with the correct
sequence number, stopping everyone else from using this LU.
Additional query words: Lost locality Bind sequence
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Keywords :
Technology : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ400 kbSNAServ300SP3 kbSNAServ300SP1 kbSNAServ400SP1 kbSNAServ300SP2
Version : :3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1
Issue type : kbbug
Solution Type : kbfix
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