KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q162594: SNARAS Receives 651 RAS Error After Failed Connection Attempt

Article: Q162594
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11,2.11 SP1,3.0,4.0
Operating System(s): 
Keyword(s): kbnetwork
Last Modified: 12-JUN-2001

-------------------------------------------------------------------------------
The information in this article applies to:

- Microsoft SNA Server, versions 2.0, 2.1, 2.11, 2.11 SP1, 3.0, 4.0 
-------------------------------------------------------------------------------


SYMPTOMS
========

You may want to use the NETBIOS interface made available in SNARAS to employ
Microsoft networking over your existing SNA network, which consists mainly of
9600 SDLC multidrop links. This would allow you to use Systems Management Server
remote control facilities and manage your computers running Windows NT Server
through the Windows NT Administrative Utilities and the SNA Administrator UI.

However, implementing SNARAS over slow SDLC links on WAN networks can result in
the following errors. When the SNARAS connection is dialed using the remote
access client phonebook, after 10 seconds or so the following error message
appears:

  Error 629
  Port was disconnected by remote machine.

At this point, you have the option to cancel or retry. If you click Retry, after
about 5 seconds the following error message may appear:

  Error 651
  Your modem or other connecting device has reported an error.

CAUSE
=====

The very low network bandwidth being used is insufficient to host the complex
protocols employed to achieve Microsoft networking. The low bandwidth is further
eroded as peer entities in all the protocol stacks being used time out request
and initiate their retransmission routines.

The problem ultimately is the low bandwidth of the end-to-end connection, which
can be as low as 120 KBps as a result of a mixture of low speed SDLC links
between FEPs and other SNA traffic over the same links. SNARAS provides a
guaranteed delivery, but RAS "believes" that it is not guaranteed and this level
of bandwidth is too low for RAS to use.

RESOLUTION
==========

Upgrade slow links to links that can adequately handle NetBIOS/Server Message
Block (SMB) traffic.

MORE INFORMATION
================

Within the SNARAS components connection timeouts can be seen by employing the
checked versions of Snaras.dll and Rassna.dll to produce internal tracing, as
demonstrated below:

RASSNA.DLL internal tracing
---------------------------

66:d5 RasSna1 SriBindOutgoingComplete: issue connect
66:d5 RasSna1 SriConnect: sent OK
66:d5 SriCallback - message 0x14B378 type 259 rc 9
66:d5 RasSna1 SriConnectComplete: rc=9
66:d5 RasSna1 SriConnectComplete: failed, rc=9
66:d5 RasSna1 SriConnectComplete: setting event 000001A4
66:b6 RasSna1 DeviceWork: Entered
66:b6 RasSna1 DeviceWork: resetting event 000001A4
66:b6 RasSna1 DeviceWork: LastError = 651
66:b6 RasSna1 DeviceWork: Exit rc=651

SNARAS.DLL internal tracing
---------------------------

66:d5 ProcessAPPCWork - Outstanding verbs on conv 0
66:d5 RAS_LINE_CONNECTING
66:d5 RECEIVEANDWAIT complete on AAR, rc1 0, rc2 0
66:d5 RAWComplete - connect error so terminate line
66:d5 TermLine - start terminate on line AA
66:d5 Client, Send TP id=03000000A03A1700
66:d5 IssueTPEnded - issue TP Ended type 1 on AAS

However, these failures occur as a result of an underlying network failure which
can be seen if RAS PPP logging is enabled. The logs will show PPP packets get
received a very long time after they are sent, causing PPP LCP to come down and
re-negotiate. So LCP goes up and down for a long time until it disconnects. This
is called a cross connection.


Although there are Microsoft Knowledge Base articles that describe how to tune
timing parameters in the network protocols right up to SMB layer, Microsoft
network architecture is not designed to work over networks offering such low
bandwidth.


STATUS
======


Additional query words: prodsna

======================================================================
Keywords          : kbnetwork 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ200 kbSNAServ211 kbSNAServ400 kbSNAServ210 kbSNAServ211SP1
Version           : WINDOWS:2.0,2.1,2.11,2.11 SP1,3.0,4.0

=============================================================================

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.