KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q114124: PC MMTA: External Configured for CommType=X25Eicon May Hang

Article: Q114124
Product(s): Microsoft Mail For PC Networks
Version(s): WINDOWS:3.2
Operating System(s): 
Keyword(s): 
Last Modified: 11-NOV-1999

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

- Microsoft Mail for PC Networks, version 3.2 
-------------------------------------------------------------------------------

SYMPTOMS
========

An MS-DOS message transfer agent (MTA) or OS/2 multitasking MTA (MMTA) session
started with the Commtype=X25Eicon switch stops responding (hangs). No X.25
Call-Requests go out and all incoming calls in that session or other instances,
if any, are rejected. Following the hang, the MMTA session typically will not
respond to the ESC key to terminate.

CAUSE
=====

An Eicon adapter tracks network control blocks (NCBs) by putting them in queues
labeled Free, Active, Completed, and Unknown. On one Eicon adapter there can be
a maximum of 245 NCBs allocated simultaneously. The NCBs are released to the
Free queue when an X.25 application calls the Eicon application programming
interface (API) routine X25DONE.

When initiating a transfer, the MMTA session issues a Call-Request to the Eicon
adapter. The Eicon adapter allocates two NCBs per Call-Request, regardless of
whether or not an X.25 virtual circuit (VC) has actually been established with a
remote MMTA. Although the MMTA does issue an X25HANGUP call when a message
transfer is complete, it does not call X25DONE.

This causes NCBs to accumulate in the Completed queue, never to return to the
Free queue. When an MMTA session sends the 126th NCB (roughly), given two NCBs
per Call-Request, the adapter hangs and does not process any more incoming or
outgoing calls. Following this, the MMTA session that sent the last Call-Request
hangs.

WORKAROUND
==========

Currently, two workarounds are available:

- Use the -BR (break relative) switch on the MMTA command line to periodically
  terminate X.25 MMTA sessions.

- Restart the computer containing the Eicon adapter. This will re-initialize
  the adapter. If you are running OS/2, any additional X.25 MMTA instances will
  be disabled until this is done.

STATUS
======

Microsoft has confirmed this to be a problem in the MTA for version 3.2 of
Microsoft Mail for PC Networks and in the MMTA for OS/2. This was fixed with
External version 3.2.6 for both MS-DOS and OS/2.


Additional query words: 3.20 breakrelative

======================================================================
Keywords          :  
Technology        : kbMailSearch kbZNotKeyword3 kbMailPCN320
Version           : WINDOWS:3.2

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

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.