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Appendix E: Microsoft SNA Server v3.0


Note: Screen snapshots are copyright Microsoft Corporation


This document provides sample views of an 802.2 DLC connection for Microsoft SNA Server Verion 3.0 for 95/NT. We have validated the CCIAPPC component against Microsoft SNA Server version 3.0. This document is arranged in a logical sequence for a new installation of the SNA Server product.

E.1 Installing DLC for Windows NT or '95

Microsoft SNA Server requires the Microsoft 32-Bit DLC protocol to provide support for a connection over 802.2. You should already have installed the 32-bit DLC driver for Windows '95 or Windows NT. If you have not yet done this, please follow the instructions for installing this driver in Configuring DLC over 802.2 on Windows 95 or Configuring DLC over 802.2 on Windows NT.

E.2 Installing Microsoft SNA Server

This documentation assumes that you have already installed Microsoft SNA Server. In addition you should have specified the MS DLC in the SNA Server Setup program.

E.3 Configuring Microsoft SNA Server

After succesfully installing the SNA Server product, you can start to configure your APPC connection. You should have a VTAM definition of the connection you are attempting to configure available to you during the configuration.

From the Microsoft SNA Server(Common) program folder, start the Manager program.

E.4 Step 1: Configuring The Local Server

During the SNA Server 3.0 installation (assuming that you are performing a new installation and not an upgrade) you will be prompted for information about the Local Server.

  1. Enter the Network Name for this SNA network. This should be obtained from the network administrator of the host system.
  2. Enter the Control Point (CP) name assigned to this machine. This should be obtained from the network administrator of the host system. The CP Name should match the Physical Unit (PU) name assigned to this machine as specified in the PU definition in VTAM for this machine.

E.5 Step 2: Configuring The Link Service

Now configure the Link Service by selecting the Insert menu item then Link Service. This will display the Insert Link Service dialog box.

  1. Select DLC 802.2 Link Service which is the Microsoft 32 Bit DLC installed previously.
  2. Select Add... to add the Link Service.

This will display the DLC 802.2 Link Service Properties dialog box.

  1. Select the correct LAN adapter over which the Link Service will be used.
  2. Leave the Local Service Access Point (SAP) to default to 0x4.
  3. Leave the Allow Link Service To Be Distributed option un-selected.
  4. Hit the OK button to complete the configuration of the Link Service.

E.6 Step 3: Configuring The Connection

  1. Under the SNA Servers folder select the local Server which you have just configured in Steps 1 and 2 above.
  2. In the Insert menu choose Connection and then the connection type 802.2, at which point the Connection Properties dialog box will appear.
  3. Fill in the Connection Name with a name up to 8 characters long which will describe the connection, e.g. the destination of the connection.
  4. Select the Link Service SnaDlc1, this is the protocol which will be used to access the network adapter.
  5. For the Remote End select Host System.
  6. Set the Allowed Directions to both Incoming and Outgoing.
  7. Set the Activation to By Administrator initially. This can be changed to On Demand or At Server Startup later when we are sure that the connection is configured correctly.

E.7 Step 4: Configuring The Connection Address

Now display the Address dialog box by clicking on the Address tag in the Connection Properties dialog box.

E.8 Step 5: Configuring The System Identification

Now display the System Identification dialog box by clicking on the System Identification tag in the Connection Properties dialog box.

  1. Enter the 8 digit hexadecimal Local Node ID which is used to identify this local system on the SNA network. The first 3 digits is the block (IDBLK) number followed by the last 5 digits of the node (IDNUM) number. These numbers must correspond with the IDBLK and IDNUM fields of the PU definition for this machine as defined in VTAM on the host system.

The XID Type should reflect the type used by the host system. At this point you must check with the network administrator of the host system to see whether the host system uses Format 3 type XIDs. Format 0 only sends the local Node ID and is used only when hosts do not support the default Format 3 XID. Format 3 sends up to 100 bytes of identification data which includes the local Node ID and the Control Point name. Independent APPC LUs must use format 3 XIDs. The default is Format 3.

Also check with the network administrator of the host system whether the Node Id of the host system should be configured.

E.9 Step 6: Configuring 802.2 DLC Properties

Now display the 802.2 DLC dialog box by clicking on the 802.2 DLC tag in the Connection Properties dialog box.

The 802.2 DLC settings contain parameters which in most cases can be left to their default values. Two which may need modification are the BTU Length and the Connection Retry Limits.

  1. Specify a value for the maximum BTU Length based on the following formula. BTU = MAXDATA - 9, where MAXDATA is the value of the MAXDATA parameter of the PU definition for this machine. NOTE: For a 4 Mbs Token Ring specify a BTU value of 4195 or less. For a 16 Mbs Token Ring specify a value of 16393 or less. For an Ethernet LAN specify a BTU value of 1493 or less.
  2. Set a value for the Maximum Retries which the SNA Server will make when attempting to establish the connection with the host system. The possible values range from 1 to Unlimited. We suggest a value of 2.
  3. Set a value for the Delay After Failure. This is a value in seconds between each attempt. The range is from 5 to 255 seconds, with a default of 10.

To complete the configuration of the connection click on the OK button.

Before attempting to communicate using CCIAPPC you must define the local and remote LUs which will be used to communicate over the SNA connection you have configured. In this section we will describe the configuration of Independent LUs to be used to communicate over the host connection. When communicating with Host systems running VTAM (or NCP) the Remote LU is known as the APPLID (pronounced 'apple-eye-dee').

E.10 Step 7: Configuring Local LUs

  1. Under the SNA Servers folder select the local Server which you have just configured in Steps 1 and 2 above.
  2. In the Insert menu select APPC and then Local LU at which point the Local APPC LU Properties dialog box should appear.
  3. For the LU Alias specify the LU name as defined in the list of LUs defined for this PU in VTAM on the host system. This name is automatically duplicated for the LU Name.
  4. Select the Network Name field, this will cause the Network Name to be automatically set to the Network Name of the Local Server. The Network Name and LU Name together form the Fully Qualified LU Name.
  5. Leave the APPC SyncPoint Support box un-selected.

Now select the Advanced tab in the Local APPC LU Properties dialog box.

  1. Select the check box marked Member of Default Outgoing Local APPC LU Pool.
  2. Select an LU 6.2 Type of Independent.

To complete the configuration of the Local LU click on the OK button.

E.11 Step 8: Configuring Remote LUs

Unlike Local LUs, Remote LUs are assigned to a connection which will be used to communicate with it.

  1. Under the SNA Servers folder select the local Server which you have just configured in Steps 1 and 2 above.
  2. In the Insert menu select APPC and then Remote LU at which point the Remote APPC LU Properties dialog box should appear.
  3. Select the Connection over which this Remote LU will be used. This will be the Connection configured in Step 3.
  4. Enter the LU Alias, this name is automatically duplicated for the LU Name and Uninterpreted Name. This LU Name should match the definition of the LU as it exists on the remote system, in this case in the form of a VTAM APPL definition on the host system.
  5. Select the Network Name field, this will cause the Network Name to be automatically set to the Network Name of the Remote Node Name.

Now select the Options tab in the Remote APPC LU Properties dialog box.

To complete the configuration of the Remote LU click on the OK button.

E.12 Configuring Session Limits: Defining a Mode

A Mode is used to define the attributes of sessions used between a Local LU and a Remote LU.

If the default mode #INTER is not appropriate (because its settings are incompatible with the modes defined on the host system for the Remote LU, or perhaps because a larger number of sessions is required) then a new mode can be defined.

CCIAPPC uses a single APPC session for each CCI session between the client and the server (e.g. between the MFA client and Fileshare running on a mainframe). When CCIAPPC establishes a connection between the client and server the attributes of the Mode determine, amongst other things, the number of CCI sessions available between the Local LU and the Remote LU (APPLID in VTAM). Hence the Mode determines how many client sessions can be established using the same Local LU - Remote LU pairing.

The Parallel Session Limit and the Minimum Contention Winner Limit together determine how many sessions can be established by the Local LU (see below).

For example: if 10 client sessions are required, all using the same Local LU then the Mode session attributes might be:

Parallel Session Limit = 20
Minimum Contention Winner Limit = 15
Partner Minimum Contention Winner Limit = 0

Alternatively the same number of client sessions could be attained by using multiple Local LUs with the client sessions divided between these LUs.


IMPORTANT NOTE: When a connection is established between a Local LU and a Remote LU the Mode characteristics are negotiated. This means that it is possible that the partner system (e.g. mainframe) will reduce the session limits to values which it can support. This may mean that fewer client sessions than expected will be supported. Hence it is important that the Mode characteristics, as defined for both the Local and Remote LUs, are compatible.


E.12.1 To define a new Mode:

  1. In the Insert menu select APPC then Mode Definition at which point the APPC Mode Properties dialog box should appear.
  2. Enter Mode Name, this should match the Mode Name as defined on the Host system in VTAM. This can be the default log mode specified by the DLOGMOD parameter of the VTAM Applid (APPL) definition.

Now select the Limits tab in the APPC Mode Properties dialog box.

  1. Enter the Parallel Session Limit. This is the maximum number of sessions that can be established between the two LUs.
  2. Enter the Minimum Contention Winner Limit. This is the number of sessions that the Local LU can establish without needing the permission of the Remote LU.
  3. Enter the Partner Min Contention Winner Limit. This is the number of sessions that the Remote LU can establish without needing the permission of the Local LU. Note that the sum of the Minimum and Partner Min Contention Winner Limits must be less than or equal to the Parallel Session Limit.
  4. Enter the Automatic Activation Limit. This is the number of contention winner sessions to activate when the connection using this mode is started.

If you are in doubt over these values check with the network administrator of the host system.

Now select the Characteristics tab in the APPC Mode Properties dialog box.

  1. Enter the Pacing Send Count and Pacing Receive Count. These values should be obtained from the system administrator of the host system.
  2. Enter the Max Send RU size and Max Receive RU size. These values should be obtained from the system administrator of the host system.
  3. Select High Priority Mode.

Select OK to complete the Mode definition. The new Mode should appear in the APPC Modes folder.

Repeat this section until all required Modes have been added.

E.13 Step 9: Enabling CCIAPPC To Find The Local LU

It is very important that the CCIAPPC module be able to determine the Local LU to use for communication with the Host application. You may have configured everything else correctly and all of your other APPC applications may work, but if you miss this final step you will fail to establish a CCI session with the host application. If the CCI-INITCLIENT call returns CCI error 9 and CCI_GETERROR returns the message "CCIAPPC failed to allocate an APPC session, ensure that Local LU is defined" it is likely that you have failed to complete this final step. When CCIAPPC attempts to allocate an LU 6.2 session with the remote system it must specify the Remote LU name which it requires a session with. This is the Remote LU name specified in the CCI Servername parameter (e.g. the /S parameter in FHREDIR.CFG). However, APPC needs to know the Local LU name as well as the Remote LU name when attempting to establish a session between the LUs.

The manner in which it determines the Local LU name in SNA Server is by one of two mechanisms as described below:

  1. Configure the Local LU to be a member of the Default Outgoing Pool.

    When we configured the Local LU above, we selected the check box marked Member of Default Outgoing Local APPC LU Pool in the APPC LU Properties dialog box. This means that when CCIAPPC attempts to allocate a session with the Remote LU it will select a Local LU which is a member of the Default Outgoing Pool. However, if there are multiple Local LUs which are members of the Default Outgoing Pool then any of these Local LUs could be selected. If this side-effect is undesirable then implement the following method.

  2. Configure a default Local APPC LU Alias on per user or group basis.
    1. If the user or group has already been configured in SNA Server then skip to step number 6, otherwise perform steps 2 to 5 first.
    2. In the Insert menu select User at which point the Add Users and Groups dialog box should appear.
    3. Select the domain from which to add the users or groups or select the local server name.
    4. Select the user or group from the list in the Names list box (select the Members... button to list the users in a group) and then select Add.
    5. Click the OK button.
    6. In the Configured Users folder double-click on the user or group with which you want to associate a default Local APPC LU.
    7. In the users' properties dialog box select the APPC Defaults tag.
    8. Select the the required Local LU from the Local APPC LU popdown list.
    9. Click the OK button.

Now go to the File menu and select Save. It is not necessary to restart the SNA Server service to activate a new User configuration.

E.14 Step 10: Configuring a 3270 LU for the 3270 Applet

In order to use the SNA Server 3270 Applet for 3270 terminal access to the host system a 3270 LU must be configured for use by each terminal session.

  1. In the Connections folder select the connection over which the 3270 session will be used.
  2. In the Insert menu select 3270 and then Display LU at which point the 3270 LU Properties dialog box should appear.
  3. Set the LU Number for this dependent LU. This must match the LOCADDR number as specified on the Dependent LU definition configured for use as a 3270 terminal. This is found under the PU definition for the SNA Server machine in VTAM.
  4. Enter the LU Name for the 3270 LU. This should match the name of the Dependent LU definition configured for use as a 3270 terminal. This is found under the PU definition for the SNA Server machine in VTAM.

Now select the Display Model tab in the 3270 LU Properties dialog box.

Click the OK button to complete the 3270 LU configuration

Repeat Step 10 until you have configured all the 3270 LUs which you require for 3270 terminal sessions.

E.15 Step 11: Associating a 3270 LU with a User

When a user runs the SNA Server 3270 Applet a 3270 LU is required in order to establish a session with the host system. This 3270 LU may come from a pool of 3270 LUs or may be associated with the user. We will describe the latter case, associating a 3270 LU with a user.

  1. If the user has not yet been configured in SNA Server then see the second part of Step 9 above.
  2. In the Connections folder select the connection and then the 3270 LU which you wish to assign to a configured user.
  3. Whilst selecting the 3270 LU with the mouse pointer, click the right mouse button and select Assign To followed by User and then select the required user.
  4. In the Configured Users folder select the same user. The newly assigned 3270 LU should appear .

Now go to the File menu and select Save Configuration. It is not necessary to restart the SNA Server service to activate a new User configuration.

When the specified user starts the SNA Server 3270 Applet a session will be established using the 3270 LU associated with the user.

E.16 Step 12: Activating the Configuration

Once the settings described above have been made the configuration must be saved before stopping and restarting the SNA Server service.

  1. In the File menu select Save to save the configuration.
  2. In the SNA Servers folder select the server and in the Service menu select Stop.
  3. Once the server status has gone to Inactive, in the Service menu select Start, the service should then go to Active status.

Once the service is active the underlying connections will activate if the Activation type was defined as On Server Startup or On Demand.

Connections configured for Incoming and Outgoing calls go to On Demand/Incoming status when successfully activated. The connection will go to active status when the first session is established or if activated manually by the administrator.

E.17 Step 13: Error Reporting and Diagnostics

E.18 Known Problems

  1. Running Microsoft SNA Server 3.0 with Novell Netware 32 Bit Client

    There is a problem running Microsoft SNA Server v3.0 on Windows NT Servers which are also running the Novell Netware 32 Bit Client. The SNA Server service can cause Windows NT to crash or the service itself may trap. Microsoft are aware of this problem and plan to address this with SNA Server v3.0 Service Pack 2 (SP2). This problem does not exist with the Microsoft Netware Client.

  2. Attempting to install Microsoft SNA Server 3.0 on an NT Server configured in a WorkGroup

    Microsoft SNA Server 3.0 MUST be installed on an NT Server which is EITHER a Domain Controller OR is configured in a Domain (where another Server is the Domain Controller). The NT Server must NOT be configured in a WorkGroup.


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