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Q139594: Meaning of "DLCST UPSN" in a SNA Server Data Link Control Trace

Article: Q139594
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11,3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1
Operating System(s): 
Keyword(s): kbinterop kbnetwork kbsetup kbsna300sp1 kbsna300sp2 kbsna300sp3 sna4
Last Modified: 12-JUN-2001

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The information in this article applies to:

- Microsoft SNA Server, versions 2.0, 2.1, 2.11, 3.0, 3.0 SP1, 3.0 SP2, 3.0 SP3, 4.0, 4.0 SP1 
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SUMMARY
=======

A special mechanism is used to track SDLC statistics in the SDLC link service.
The generation of statistics is controlled by byte dataru[s+27] in the
Open(LINK) request messages. An Open (LINK) request message flows between the
SNA Server service and each link service whenever the SNA Server service
initializes. Its basic purpose it to set the link characteristics. The
dataru[s+27] byte is defined by the SNA Device Interface Specification (SNADIS)
as "reserved", and causes the Microsoft written SDLC link services to generate
statistic messages when set to x01. Link services written by IHVs will ignore
this byte, and therefor, not log these link statistics in a trace.

The following trace excerpt may appear in an SNA Server Data Link Control trace.
This trace represents messages that flow between the SNA Server service and the
underlying link services:

  ...
  DLC    04161000->01110101 DLCST UPSN
  DLC                       UPTYPE:3 UPCNTR:7 COUNT:0
  ...

The definitions of the UPTYPE and UPCNTR fields are as follows. The COUNT field
is not used.

UPTYPE              UPCNTR
==========================

Type 1
            1 Number of Test cmds rcvd
                 2 Number of Test rsps sent

Type 3
                 1 Non productive receive timeout
                 2 Idle Timeout
                 3 Write retry
                 4 Receiver character overrun
                 5 Transmitter underrun
                 6 Connection problem
                 7 FCS error
                 8 Primary station abort received
                 9 SDLC Command reject
                10 DCE error
                11 Write timeout
                12 Not used
                13 I-frame received out of sequence
                14 I-frame discarded (primary)
                15 No response timeout (primary)
                16 Remote busy timeout (primary)

Because the trace excerpt has UPTYPE = 3 and UPCNTR = 7, the observer of the
trace could conclude that this is an FCS (Frame Check Sequence) error detected
by the link service.

NOTE: For earlier versions of SNA Server, theThe SNADIS guide can be found on the
SNA Server cd in Help file format. To find the Open(Link) Request format, do the
following:

1. Run SNA.HLP.

2. Select SNA Device Interface Specification.

3. Select "Chapter 4 SNA Device Interface Specification Message formats."

4. Select 4.1 Open(Link).

5. Select 4.1.1 Open(Link) Request.

For SNA Server versions 3.0 and 4.0, the SNADIS Guide is located in the SDK
Documentation, which is a component that may be installed during SNA Server
setup. To find the Open(Link) Request format, do the following:

1. Run the SDK Documentation from the Start menu in Windows NT.

2. Expand SNA Device Interface Specification.

3. Expand Reference.

4. Expand Message Formats.

5. Expand Open(LINK), and then select Open(LINK) Request.

Additional query words: prodsna

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Keywords          : kbinterop kbnetwork kbsetup kbsna300sp1 kbsna300sp2 kbsna300sp3 sna4 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ200 kbSNAServ211 kbSNAServ400 kbSNAServ210 kbSNAServ300SP3 kbSNAServ300SP1 kbSNAServ400SP1 kbSNAServ300SP2
Version           : WINDOWS:2.0,2.1,2.11,3.0,3.0 SP1,3.0 SP2,3.0 SP3,4.0,4.0 SP1

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