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Q143354: PC Ext Gen: Questions Asked About X.25 and External [Part 1]

Article: Q143354
Product(s): Microsoft Mail For PC Networks
Version(s): WINDOWS:3.0a,3.2,3.2a,3.5; :3.2,3.5
Operating System(s): 
Keyword(s): 
Last Modified: 20-NOV-1999

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The information in this article applies to:

- Microsoft Mail for PC Networks, versions 3.0a, 3.2, 3.2a, 3.5 
- Microsoft Mail Multitasking MTA, version 3.2 
- Microsoft Mail Multitasking MTA for Windows NT, version 3.5 
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SUMMARY
=======

When you set up the Mail External program (EXTERNAL.EXE) computers so that they
can communicate via X.25, it may require a substantial amount of configuration.
The following section may answer some of the related questions.

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

The following are some of the frequently asked questions related to X.25:

1. Q. What X.25 boards are supported by the Microsoft Mail Gateway to X.400?

  A. The Eicon X.25 board is supported.


2. Q. Do I have to run a separate instance of the Mail External program to
  monitor or use each of the four channels of the Eicon card?

  A. Yes, an instance of External can handle only one X.25 virtual circuit (VC).
  If there must be two concurrent X.25 sessions, then two X.25 External
  instances must be configured with the following parameter:

  COMMTYPE=X25<card-type>

3. Q. What is the difference between these terms: virtual channels, virtual
  circuit (VC), physical channels, logical channels, ports, sessions, logical
  channel number (LCN), and logical session number (LSN)?

  A. The term virtual channel is confused with virtual circuit. Virtual channels
  do not exist; instead, it is a physical channel or port. Each Eicon board has
  one or four ports.

  A physical channel is the physical link provided by the X.25 vendor (for
  example, Infonet) to communicate with each port.

  A virtual circuit is the logical connection or session. A virtual circuit is
  the X.25 network layer term. The virtual circuit exists at the time of the
  communication only.

  The logical channel number (LCN) is the same as the virtual circuit number
  (VCN) but at the X.25 datalink layer. Each Eicon port can handle up to 99
  virtual circuits; each of them has its own VCN.

  The logical session number (LSN) is the term used by Eicon to lump the two
  terms LCN and VCN together; the sessions open over a physical port one at a
  time.

4. Q. Is the virtual channel number the same thing as X.25 port numbers?

  A. A port (physical channel) is not the same as a virtual circuit (VC). Each
  Eicon board can have up to four ports; each port can handle up to 99 VCs.
  Each Eicon card can handle up to 396 VCs through four ports.

5. Q. How can we specify the virtual circuits?

  A. Virtual circuits (VC) cannot be specified, which is the X.25 packet and
  logical channel number (X.25 datalink layer term). You can only specify the
  port number (physical channel) and a subaddress number.

  The Eicon card manages which VC and logical channel number (LCN) or logical
  session number (LSN) will be assigned to the X.25 session. The assigned LCN
  is transparent to the user and will be reassigned after the VC is dissolved.

6. Q. Do I have to specify the port number? If so, how is this done?

  A. If you have multiple X.25 ports supported on the Eicon card under OS/2,
  then specify each channel with the parameter:

  X25PortNumber=<n>

  where "n" is the port number, in one of the four External instances running
  under the OS/2 MMTA. If you do not specify a port number, the card may
  default to port 1.

  It is recommended that you use the parameter, X25PortNumber, for each
  instance. You will also need the parameter for the Eicon board:

  CommType=X25Eicon

  In addition, you will need the long X.121 address from the X.25 vendor. The
  two digit subaddress specifies the originating address of the External
  program. The two digit subaddress is required for the Eicon boards. For
  example,

  X25subaddress=<x25originatingaddress>.

7. Q. How do you use each of the virtual circuits (conversations) provided by
  the X.25 vendor for every port of the Eicon card?

  A. Run a separate instance of External for every virtual circuit. When the
  first channel is busy, all calls (in or out) will be routed to the second
  channel, etc. However, to achieve 99 concurrent X.25 connections (virtual
  circuits), you need 99 instances of the Mail External program. Each instance
  of the External handles one VC.

8. Q. How do you specify the X.25 destination address and X.25 listen address?

  A. Each physical connection (node or DCE) has an X.25 address associated with
  it. Specify the node listen address in the EXTERNAL.INI file by the
  parameter:

  X25subaddress=313023022

  (plus the optional two-digit subaddress), to the MTA computer ID on the local
  area network (LAN). Enter the listen address from the vendor for example:

  Port=<long X.25 Address>=<InfoNet DCE>

  Specify the destination MTA address in the External-Admin, Setup, and put the
  address (for example, 313023022) plus any optional two-digit subaddress in
  the local EXTERNAL.INI file.

For additional information regarding configuring X.25 and the Mail External
program, please reference the Microsoft Mail for PC Networks "Administrator's
Guide," Appendix F "X.25 Settings for Mail."

For additional information regarding the configuration of an X.400 gateway using
X.25, refer to the Microsoft Mail Gateway to X.400 "Administrator's Guide."

Additional query words: 3.00 faq

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Keywords          :  
Technology        : kbZNotKeyword2 kbMailSearch kbZNotKeyword3 kbMailPCN320 kbMailPCN320a kbMailPCN300a kbMailPCN350 kbMailMMTA320 kbMailMMTA350NT
Version           : WINDOWS:3.0a,3.2,3.2a,3.5; :3.2,3.5

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