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Q107192: Multiple Connections to the Same Host Over 802.2

Article: Q107192
Product(s): Microsoft SNA Server
Version(s): WINDOWS:2.0,2.1,2.11,3.0,4.0
Operating System(s): 
Keyword(s): kbnetwork 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, 4.0 
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SUMMARY
=======

SNA Server for Windows NT supports up to 250 connections (PUs) over a single SNA
Server 802.2 link service, where each connection is communicating to a different
IBM host, peer system (such as AS/400) or downstream (DSPU) device. However, to
communicate to the same SNA destination, two SNA Server 802.2 link services and
connections must be configured when using SNA Server 3.0 SP1 and earlier.

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

An SNA Server connection is equivalent to an IBM SNA Physical Unit Type 2.0 or
2.1. When communicating to different destinations (such as multiple 3745 and
AS/400 computers), SNA Server supports up to 250 simultaneous connections over
one 802.2 link service.

However, when communicating to the same destination (for example, to one 3745),
two SNA Server 802.2 link services must be defined (each with it's own SAP
address), and a separate 802.2 connection must be defined through the SNA Server
Admin/Manager program to use each 802.2 link service. Note that multiple SNA
Server 802.2 link services can operate over a single 802.2 adapter, though each
link service must be configured with a unique SAP address.

SNA Server 2.x
--------------

To define two SNA Server 802.2 link services in the SNA Server Setup program, do
the following:

1. From the Setup Option dialog box, Select Configure Link Services.

2. Select Add, then highlight SNA DLC 802.2 Link Service and choose Install.

3. Enter a title describing the link service (or leave the default title), then
  select the adapter the link service will use.

4. Leave the SAP default to 4

5. Repeat the previous steps to add the second 802.2 Link Service, except in
  step 4, set the SAP value to 8.

To exit Setup, choose Continue repeatedly until Setup displays an option to exit
or start SNA Admin.

SNA Server 3.0 and 3.0 SP1
--------------------------

To define two SNA Server 802.2 link services in the SNA Server Manager, do the
following:

1. From the Manager Menu Bar, Select Insert -> Link Service.

2. Highlight DLC 802.2 Link Service and choose Add.

3. Enter a title describing the link service (or leave the default title), then
  select the adapter the link service will use.

4. Leave the SAP default to 4

5. Repeat Steps 2 through 4 to add the second 802.2 Link Service, except in step
  4, set the SAP value to 8.

To exit the Insert Link Service dialog, choose Finish.

SNA Server 3.0 SP2 and Later
----------------------------

SNA Server 3.0 SP2 added a Multi-SAP capability to the DLC 802.2 Link Service.
This feature allows a single DLC 802.2 Link Service to use multiple Local SAP
addresses. This allows the Local and Remote SAPs to be configured on a per
connection basis. To add a DLC 802.2 Link Service using the Multi-SAP feature,
do the following:

1. From the Manager Menu Bar, Select Insert -> Link Service.

2. Highlight DLC 802.2 Link Service and choose Add.

3. Enter a title describing the link service (or leave the default title), then
  select the adapter the link service will use.

4. Uncheck the "Use Fixed SAP" option. Note that the "Local Service Access Point
  (SAP)" option is now greyed out.

To exit the Insert Link Service dialog, choose Finish. To define an SNA Server
802.2 link service in the SNA Server Admin/Manager program, do the following:

1. From the SNA Server Admin program, configure both connections with the
  appropriate Remote Network Address (which may be the same for both
  connections). Note that the Local Node ID will be unique for each connection,
  since each connection must refer to a unique PU at the host (where the Local
  Node ID must correspond with the IDBLK + IDNUM parameters on the PU
  definition in VTAM).

  NOTE: If you are using the Multi-SAP feature of SNA Server 3.0 SP2 and later,
  the SAPs are configured on the same property page as the Remote Network
  Address. Each connection should be configured with a unique "Local SAP
  Address."

  NOTE: VTAM also supports the configuration of a "CPNAME" (control point name)
  parameter in the PU definition. This control point name must match the local
  control point name in the "Server Properties" dialog in the SNA Admin
  program. SNA Server sends the local network name and control point name to
  the host in the XID Format 3 message during connection establishment.
  However, SNA Server 2.x only supports the configuration of a single local
  network name and control point name. If SNA Server is to support multiple
  connections (or PUs) to the same host system, and VTAM is configured with
  unique "CPNAME" parameters on each PU, the SNA Server local network name and
  control point name values in the server properties dialog must be left blank,
  and the Local Node ID configured on the connection dialog must be used to
  distinguish the PU to be used. So, in this configuration, VTAM must be
  configured with unique IDBLK and IDNUM parameters for each PU that SNA Server
  is to use.

2. Add the required LUs (and optionally, LU pools) and save the configuration
  before restarting the SNA Server service.

SNA Server user/group records can be added after the SNA Server service has been
started, though the configuration must be saved before these additions are
available to the SNA Server client machine(s).

Additional query words: prodsna DLC 802.2 snafaq

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Keywords          : kbnetwork sna4 
Technology        : kbAudDeveloper kbSNAServSearch kbSNAServ300 kbSNAServ200 kbSNAServ211 kbSNAServ400 kbSNAServ210
Version           : WINDOWS:2.0,2.1,2.11,3.0,4.0

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