SNA Server 3.0 Supports Multiple Connections to Same AS/400

MORE INFORMATION

For SNA Server to connect to an AS/400, an APPC controller definition must exist for SNA Server's local control point name. The APPC controller may be autocreated by the AS/400 or manually created by the AS/400 administrator.

The AS/400 allows only a single APPC controller, with a given control point name, over any line it supports. Previous versions of SNA Server can only be configured with one local control point name. SNA Server versions 3.0 and later allow the local control point name to be overridden for each connection defined for a particular SNA Server. This allows multiple APPC controllers to be created for a single SNA Server.

The following is an example of two 802.2 connections to the same AS/400:

1. Install two DLC 802.2 Link Services via SNA Server Manager and configure each to use a different Local Service Access Point (SAP). The first DLC 802.2 Link Service can be setup to use the default local SAP of 0x4 and the second can be setup to use a local SAP of 0x8. For this example, we will call them SnaDlc1 and SnaDlc2.
   
   Note: SNA Server 3.0 Service Pack 2 (SP2) added a new Multi-SAP DLC Link Service feature. This feature allows a single DLC 802.2 Link Service to use multiple Local SAPs without requiring a new link service to be installed to use additional Local SAPs for DLC connecting to the same remote network address. If a DLC 802.2 Link Service is installed and configured for Multi-SAP support, there is no need to install additional DLC 802.2 link services to support multiple connections to the same AS/400. The link service is configured for Multi-SAP support by unchecking the "Use Fixed SAP" option in the DLC 802.2 Link Service Properties page. If this option is unchecked, the Local SAP for each connection is configured in the Connection Properties under the Address tab. Please refer to the SNA Server Online help for more information on the Multi-SAP DLC Link Service feature if using SNA Server 3.0 SP2 or later.
2. Create and configure an 802.2 connection for the first connection to the AS/400 by selecting Insert -> Connection -> 802.2 from the Menu Bar in Manager. The AS/400 Wizard can also be used to create and configure the connection.
   
   Note: SNA Server versions 3.0 and later do not create connections for installed link services by default like the previous versions of SNA Server did. SNA Server Manager can be configured to automatically create connections when link services are installed by checking the Automatically Create Connections for New Link Services checkbox under View -> Options.
   
   Name = Enter a 1 to 8 character connection name.
   Link Service = SnaDlc1 (or the name of one of the link
   services added in Step 1)
   Remote End = Peer System
   Allowed Directions = Outgoing Calls. Check Incoming Calls if
   you want the AS/400 to activate the link.
   Activation = If set to "On Server Startup" (default), then the
   Switched disconnect (SWTDSC) value on the AS/400
   controller definition should be set to NO. This
   causes the underlying link to stay active even if
   there are no active sessions. Otherwise, if
   SWTDSC is YES, then SNA Server should be set to
   "On Demand" activation.
   
   Select the Address tab:
   
   Remote Network Address = The Ethernet or Token Ring MAC address of the AS/400.
   
   Remote SAP Address = 0x4
   
   Note: If using the Multi-SAP DLC feature available with SNA Server 3.0 SP2 and later, set the Local SAP Address to 0x4.
   
   Select the System Identification tab:
   
   Local Node Name:
   
   Network Name = APPN (or Remote Network ID, RMTNETID value on the
   AS/400).
   Control Point Name = This is the remote control point name (RMTCPNAME)
   value in the AS/400 APPC controller definition.
   This is set to the local Windows NT machine name
   by default for all connections that are created.
   For this connection use the default value, which
   will be SNASERV1 for this example.
   Local Node ID = EXCHID value on the AS/400 controller description (if
   not specified on the AS/400, leave at default - 05D
   FFFFF).
   
   Remote Node Name:
   
   Note: The parameters in the Remote Node Name do not need to be
   specified for 802.2 connections.
   
   Network Name = APPN (or remote network ID RMTNETID value on the
   AS/400).
   Control Point Name = AS/400 local control point name, configured in the
   AS/400 Display Network Attributes screen.
   Remote Node ID = Not used (leave blank).
   
   Settings in the 802.2 DLC tab can be left at their default settings.
3. Create and configure the second 802.2 connection that will be used to communicate with the AS/400.
   
   Name = Enter a 1 to 8 character connection name. The name must
   be different from all other connections names on this
   SNA Server.
   Link Service = SnaDlc2 (The other link service that was
   installed in Step 1).
   Remote End = Peer System
   Allowed Directions = Outgoing Calls. Check Incoming Calls if
   you want the AS/400 to activate the link.
   Activation = If set to "On Server Startup" (default), then the
   Switched disconnect (SWTDSC) value on the AS/400
   controller definition should be set to NO. This
   causes the underlying link to stay active even if
   there are no active sessions. Otherwise, if
   SWTDSC is YES, then SNA Server should be set to
   "On Demand" activation.
   
   Select the Address tab:
   
   Remote Network Address = The Ethernet or Token Ring MAC address of the
   AS/400.
   Remote SAP Address = 0x4
   
   Note: If using the Multi-SAP DLC feature available with SNA Server 3.0 SP2 and later, set the Local SAP Address to 0x8.
   
   Select the System Identification tab:
   
   Local Node Name:
   
   Network Name = APPN (or Remote Network ID, RMTNETID value on the
   AS/400).
   Control Point Name = SNASERV2 (Specify a value different than the one
   used for the previous connection. Note: *** This
   is the key parameter for allowing multiple APPN-
   capable connections from a SNA Server to the same
   AS/400. *** )
   
   Local Node ID = EXCHID value on the AS/400 controller description (if
   not specified on the AS/400, leave at default - 05D
   FFFFF).
   
   Remote Node Name:
   
   Note: The parameters in the Remote Node Name do not need to be
   specified for 802.2 connections.
   
   Network Name = APPN (or remote network ID RMTNETID value on the
   AS/400).
   Control Point Name = AS/400 local control point name, configured in the
   AS/400 Display Network Attributes screen.
   Remote Node ID = Not used (leave blank).
   
   Settings in the 802.2 DLC tab can be left at their default settings.
4. Create two Local APPC LUs for the SNA Server by selecting Insert -> APPC -> Local LU from the SNA Server Manager menu bar.
   
   Note: If only one Local APPC LU is created, there will be device conflicts when users try to get sessions over each Remote APPC LU if the APPC Device Name is left blank in the 5250 Emulator configuration. This occurs because the default Device Names are generated from the Local APPC LU Name (in other words, LOCALS1, LOCALS2, and so on). If every 5250 Emulator is configured to use a unique device name, this conflict will not occur.
5. Create a Remote APPC LU for each connection to the AS/400 by selecting Insert -> APPC -> Remote LU from the SNA Server Manager menu bar. The Remote LU Alias will be different for each Remote LU, but the Remote LU Name will be the same for both Remote LUs.

For additional information on configuring an SNA Server to communicate with an AS/400 over 802.2, please see the following article in the Microsoft Knowledge Base: For additional information on configuring an SNA Server to communicate with an AS/400 over SDLC, please see the following article in the Microsoft Knowledge Base: