Downstream PU to DEC Server May Fail with Event 56: XID Reject

ID: Q149444

The information in this article applies to:

Microsoft SNA Server, versions 2.0, 2.1, 2.11, 3.0
on the following platforms: NT

SYMPTOMS

When you try to configure Microsoft SNA server as a Downstream Physical Unit (DSPU) to an DEC SNA Peer Server, you may get an XID exchange failure resulting in the link entering a pending state and failing to activate.

The Microsoft Windows NT application event log may contain an EventID 56 with the following description referencing xxxxx as the failing connection:

Connection xxxxx failed: XID rejected by remote computer.

Further investigation using the SNA tracing utility may demonstrate an XID exchange failure in CONNECTx.TRC with the following sense code:

086F0000:- Length Error: A length field within an MS major vector is invalid, or two or more length fields are incompatible.

CAUSE

There is an error in the XID3 transmitted by SNA Server version 2.11 that prevents it communicating over 802.2 DLC with some SNA PU 2.1 products that specifically validate the control vector in the XID.

The Control Vector part of the XID (byte 29 onwards for SDLC) is incorrectly formatted. The first part of the Product Set ID (X'10') Control Vector is a Product Identifier (X'11') MS Common Subvector of Product classification X'0C'. This subvector has an indicated length field of X'27'; however, it is only X'23' bytes long.

Attached is an extract from a trace (connect1.trc) of an XID exchange with a Digital SNA Peer Server. The Control Vectors start at byte 29 with '10370=3D0'(Product Set Id). The next three bytes '27110C' indicate a 0x27hex length (39 decimal) byte Product Identifier Subvector. In fact this subvector is only 0x23 hex (35 decimal) byte length:

3 byte header, X'27110C'
8 byte Software Product Common Level '021000',
15 byte Software Common Product Name 'MS SNA SERVER'
9 byte Software Product Program Number '0000000'

The trace continues with an XID rejection from the DEC Peer Server with the following sense data:

'086F0000' "Length Error: A length field within an MS major vector is invalid, or two or more length fields are incompatible.

The significant portion of Connect1.trc obtained by enabling Level 2 tracing on the link service follows:


---------------------------------------------- 15:07:24.61
 TR     XMIT XID CMD       REQUEST
 TR     ---- DLC API control block at address 73618----
 TR     000E0000 00000000 00000000 34360700      <............46..>
 TR     70000000 00000000 00001C00                     <p...........    >
 TR
 TR     00043004 00000000 00000000 0E006100      <..0...........a.>
 TR     CBE32201 6AE32201 00000000                   <.T".jT".....    >
 TR     ---- Message data ----
 TR     00005500 2000192C 00000000 0000             <..U...,......  >
 TR     ---- Message data ----
 TR     326105D0 00010000 B0841000 00000000      <2a.......d......>
 TR     00010B70 00040400 0000007F 00103700      <...p.......=7F..7.>
 TR     27110C08 04F0F2F1 F0F0F00F 06D4E240    <'....021000..MS@>
 TR     E2D5C140 E2C5D9E5 C5D90908 F0F0F0F0  <SNA@SERVER..0000>
 TR     F0F0F013 11031000 10F0F0F0 F0F0F0F0    <000......0000000>
 TR     F0F0F0F0 F0F00E09 F4C1D7D7 D54BC3D7 <000000..4APPNKCP>
 TR     F1                                                              <1
>
 TR    ---------------------------------------------- 15:07:24.61
 TR     DIR  TIMER SET     REQUEST
 TR     ---- DLC API control block at address 73698----
 TR     00220000 00000000 00000000 1E000000     <."..............>
 TR     70000000 00000000 00000000                     <p...........    >
 TR    ---------------------------------------------- 15:07:24.62
 TR     DIR  TIMER SET     ERROR - Command canceled by user
 TR     ---- DLC API control block at address 73598----
 TR     00220A00 00000000 00000000 1E000000     <."..............>
 TR     70000000 00000000 00000000                     <p...........    >

RESOLUTION

The SNA server component, Snacfg.dll, was incorrectly generating the data for the node to send and has been hotfixed to correct the problem. To implement the fix, the Snacfg.dll file must be applied and the SNA Server configuration file must be resaved using the SNA Admin program. Once saved, the SNA Server service must be stopped and started to enable the change.

STATUS

Microsoft has confirmed this to be a problem in Microsoft SNA Server versions 2.0, 2.1, 2.11, and 3.0. This problem was corrected in the latest Microsoft SNA Server 2.11 U.S. Service Pack. For information on obtaining the service pack, query on the following word in the Microsoft Knowledge Base (without the spaces):

S E R V P A C K

Additional query words: prodsna 2.00 2.10 2.11 3.50 3.51

Keywords : ntprotocol
Version : WINDOWS:2.0,2.1,2.11,3.0
Platform : WINDOWS
Issue type :