Configuring SNA Server to Talk to AS/400 Over SDLC

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This article was previously published under Q112159

SUMMARY

This article describes how to configure SNA Server to communicate with an AS/400 over an Synchronous Data Link Control (SDLC) switched (dial-up) line, to support 5250 emulation.

NOTE: The end of this article includes sample AS/400 configuration screens.

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MORE INFORMATION

These instructions assume all of the following:

The SNA Server SDLC link service has been installed using the SNA Server setup program (and any interrupt conflicts have been resolved, per the SNA Server Readme.txt file).
The system has been restarted.
AS/400 APPC controller and device description has been configured off the AS/400 SDLC line to be used (see below for sample AS/400 APPC controller and device descriptions).

Configure the following entries using the SNA Server Admin program:

Zoom on the SNA Server service (which appears as the Windows NT computer name), located in the Servers and Connections window of Admin. Enter the following parameters:

   SNA Network Control Point 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. For simplicity, this should be set to
                          the local Windows NT computer name.

   Choose OK.

Add a new Local APPC LU off the server service by clicking Insert and entering the following parameters:

      LU 6.2 Type  = Independent
      LU Alias     = For simplicity, this should be the same as the
                     Local LU Name below.
      Network Name = APPN (or Remote Network ID, RMTNETID value on the
                     AS/400).
      LU Name      = This is the remote control point name in the AS/400
                     APPC controller description (RMTCPNAME).

      All other entries can remain at default values.

NOTE: It is most efficient for all SNA Server users to use the same Local APPC LU. However, it is possible to create a unique LU for each user if desired, where the LU alias and LU name above could be replaced with the actual user name (though this requires additional administration to maintain).

Select OK.

Configure the SNA Server SDLC connection by zooming on the connection name:

      Link Service = SnaSdlc1 (or name specified during SNA setup)
      Remote End   = Peer System
      Activation   = If set to "On Demand" (default), then the Switched
                     disconnect (SWTDSC) value on the AS/400 controller
                     definition should be set to YES. This causes the
                     underlying link to drop when there are no active
                     sessions. Otherwise, if SWTDSC is set to NO, then SNA
                     Server should be set to activate On Server Startup.

      Allowed Directions = Outgoing calls.

      Zoom on the Setup button:

      Dial data = Recommend to leave blank, and configure for modem-stored
                  number dialing (assuming this is a dial-up link).
      Local Node ID =  EXCHID value on the AS/400 controller description
      Remote Node Name:
      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)

      Zoom on Advanced options:

      XID Type = Format 3
      Encoding = (NRZ or NRZI). Must match the NRZI data encoding scheme
                 (NRZI) configured on the AS/400 line description.
      Duplex = Must match the DUPLEX setting configured in the AS/400
               line description.
      Poll Address = Must match the Station address (STNADR) setting on
                     the AS/400 controller definition

      The remaining options can be left at the default

      Choose OK.

Add a new Remote APPC LU off the connection by choosing the Insert button and entering the following parameters:

      LU Alias     = For simplicity, this should be the same as the
                     Remote APPC LU Name below.
      Network Name = APPN (or remote network id RMTNETID value on the
                     AS/400)

      LU Name      = Must be set to the AS/400 local control point name
                    (set in the AS/400 Display Network Attributes screen).
      Uninterpreted LU Name = Not used (leave at default).

      Select Supports Parallel Sessions (required).

      Zoom on the Partners button. The Remote APPC LU must be partnered
      with the Local APPC LU created above, using the QPCSUPP mode. Because
      Enable Automatic Partnering is enabled by default for APPC LUs, this
      pairing will already be added.

   Choose OK.

Save the SNA Server configuration file and restart the SNA Server service. Once the SNA Server service is Active, all connections configured to activate on server startup will go into a Pending state, then switch to Active. NOTE: If the connection stays in Pending mode and doesn't activate:
1. Check the Windows NT application event log (using Event Viewer) to see the reason why the connection isn't activating. If the SDLC link service isn't activating, check the system event log for any entries logged by the IBMSYNC driver (indicating possible hardware conflicts), or the Service Control Manager (indicating why the link service was unable to start).
2. Double check the configuration entries above with your AS/400 system administrator and make sure the AS/400 line is active. If all appears okay, check the SNA Server controller description on the AS/400.
3. Check if the AS/400 is logging any errors when SNA Server attempts to establish the connection.
4. If the connection activates but users are unable to open 5250 sessions, zoom on the Status button on the Local APPC LU, which should show the following (when working correctly):
```
     Partner LU      Mode      Connection     Sessions        Limit

     <remote LU>     SNASVCMG  <connection>    0               2
     <remote LU>     QPCSUPP   <connection>    0               64

     This means that up to 64 sessions are available for use, though
     no sessions are currently active.
								
```

At this point, a 5250 user can then open any valid APPC LU/LU pair supported by any SNA Server in the domain. However, to simplify 5250 user access through SNA Server, there are various options available to an SNA Server administrator and the 5250 user, including the following:

Default AS/400 session for a user: On the SNA Server user/group record, the administrator can define default local and remote APPC LUs. If defaults are configured, and the 5250 applet is used, this is the LU/LU pair the 5250 user opens when the 5250 applet local and partner APPC LU names are left blank.
If default APPC LUs are not preassigned to a user/group, here is how to configure pools of Local APPC LUs and Remote (partner) APPC LUs to simplify 5250 user access to one or more AS/400's supported by SNA Server:

Local APPC LU pool: Define the Local APPC LU as a "Member of Default Outgoing Local APPC LU Pool". If a 5250 user does not enter a Local APPC LU when opening a session, the user accesses one of the available Local LUs in this pool.

Remote APPC LU pool: The Remote APPC LU pool is determined by the Remote LUs which are partnered with the Local APPC LU and the QPCSUPP mode. So if a Local APPC LU is specified, but the Remote APPC LU is left blank, a 5250 session is allocated from an available Remote APPC LU that it is partnered with.

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SAMPLE CONFIGURATION SETTINGS

The following AS/400 configuration screens are shown below, along with their corresponding configuration setting for SNA Server (see comments which are preceded with "****" below). This includes the AS/400 network attributes screen, SDLC (switched) line description, APPC controller, and virtual device description. Many of the configuration settings are not relevant for communications to function, though are shown here for completeness.

AS/400: Display Network Attributes

                             System:   OLYMPIA
 Current system name  . . . . . . . . . . . . . . :   OLYMPIA
   Pending system name  . . . . . . . . . . . . . :
 Local network ID . . . . . . . . . . . . . . . . :   APPN

**** Must match the remote network name on the SNA Server connection.

 Local control point name . . . . . . . . . . . . :   OLYMPIA

**** Must match the remote control point name on the SNA Server connection.

 Default local location . . . . . . . . . . . . . :   OLYMPIA
 Default mode . . . . . . . . . . . . . . . . . . :   BLANK
 APPN node type . . . . . . . . . . . . . . . . . :   *ENDNODE
 Maximum number of intermediate sessions  . . . . :   200
 Route addition resistance  . . . . . . . . . . . :   128
 Server network ID/control point name . . . . . . :   APPN        REDHOOK
 Alert status . . . . . . . . . . . . . . . . . . :   *OFF
 Alert logging status . . . . . . . . . . . . . . :   *NONE
 Alert primary focal point  . . . . . . . . . . . :   *NO
 Alert default focal point  . . . . . . . . . . . :   *NO
 Alert backup focal point . . . . . . . . . . . . :
   Network ID . . . . . . . . . . . . . . . . . . :     *NONE
 Alert focal point to request . . . . . . . . . . :
   Network ID . . . . . . . . . . . . . . . . . . :     *NONE
 Alert controller description . . . . . . . . . . :   *NONE
 Alert hold count . . . . . . . . . . . . . . . . :   0
 Alert filter . . . . . . . . . . . . . . . . . . :   *NONE
   Library  . . . . . . . . . . . . . . . . . . . :
 Message queue  . . . . . . . . . . . . . . . . . :   QSYSOPR
   Library  . . . . . . . . . . . . . . . . . . . :     QSYS
 Output queue . . . . . . . . . . . . . . . . . . :   QPRINT
   Library  . . . . . . . . . . . . . . . . . . . :     QGPL
 Job action . . . . . . . . . . . . . . . . . . . :   *FILE
 Maximum hop count  . . . . . . . . . . . . . . . :   16
 DDM request access . . . . . . . . . . . . . . . :   *OBJAUT
 PC Support request access  . . . . . . . . . . . :   *OBJAUT
 Default ISDN network type  . . . . . . . . . . . :
 Default ISDN connection list . . . . . . . . . . :   QDCCNNLANY

AS/400: Change Line Desc (SDLC) (CHGLINSDLC)

 Line description . . . . . . . . LIND         > NEWLINE
 Resource names . . . . . . . . . RSRCNAME     > LIN011
                  + for more values
 Online at IPL  . . . . . . . . . ONLINE       > *NO
 Data link role . . . . . . . . . ROLE         > *NEG
 Physical interface . . . . . . . INTERFACE    > *RS232V24
 Connection type  . . . . . . . . CNN          > *SWTPP
 Vary on wait . . . . . . . . . . VRYWAIT      > *NOWAIT
 Autocall unit  . . . . . . . . . AUTOCALL     > *NO
 Exchange identifier  . . . . . . EXCHID       > 05600001

 NRZI data encoding . . . . . . . NRZI         > *YES

**** Must match the encoding setting configured in the SNA Server
connection (located under the Advanced settings).

 Maximum controllers  . . . . . . MAXCTL       > 1
 Clocking . . . . . . . . . . . . CLOCK        > *MODEM
 Line speed . . . . . . . . . . . LINESPEED    > 9600
 Modem type supported . . . . . . MODEM        > *NORMAL
 Switched connection type . . . . SWTCNN       > *BOTH
 Autoanswer . . . . . . . . . . . AUTOANS      > *YES

**** With Autoanswer=YES, the AS/400 is answering the phone, so the SNA
Server connection should be set to "Allowed directions = Outgoing." Also,
SNA Server should be configured as "Remote end = Peer."

 Autodial . . . . . . . . . . . . AUTODIAL     > *NO
 Calling number . . . . . . . . . CALLNBR      > *NONE
 Station address  . . . . . . . . STNADR       > C1
 Connect poll retry . . . . . . . CNNPOLLRTY   > 10
 Maximum frame size . . . . . . . MAXFRAME     > 521
 Duplex . . . . . . . . . . . . . DUPLEX       > *HALF

**** Matches the SNA Server SDLC connection duplex setting (located under
the advanced settings).

 Inactivity timer . . . . . . . . INACTTMR     > 300
 Poll response delay  . . . . . . POLLRSPDLY   > 0
 Nonproductive receive timer  . . NPRDRCVTMR   > 320
 Idle timer . . . . . . . . . . . IDLTMR       > 30
 Connect poll timer . . . . . . . CNNPOLLTMR   > 30
 Poll cycle pause . . . . . . . . POLLPAUSE    > 0
 Frame retry  . . . . . . . . . . FRAMERTY     > 7
 Data Set Ready drop timer  . . . DSRDRPTMR    > 20

**** During our testing, the AS/400 default was too short. This may have to
be set to 20 or more, depending on the modem used.

 Autoanswer type  . . . . . . . . AUTOANSTYP   > *DTR
 Remote answer timer  . . . . . . RMTANSTMR    > 60
 Text 'description' . . . . . . . TEXT         > 'SHOW DEMO LINE -
DIAL IN LINE'

                   Additional Parameters

 Modem data rate select . . . . . MODEMRATE    > *FULL
 Error threshold level  . . . . . THRESHOLD    > *OFF
 Modulus  . . . . . . . . . . . . MODULUS      > 8
 Maximum outstanding frames . . . MAXOUT       > 7
 Clear To Send timer  . . . . . . CTSTMR       > 25
 Link speed . . . . . . . . . . . LINKSPEED    > 9600
 Cost/connect time  . . . . . . . COSTCNN      > 128
 Cost/byte  . . . . . . . . . . . COSTBYTE     > 128
 Security for line  . . . . . . . SECURITY     > *NONSECURE
 Propagation delay  . . . . . . . PRPDLY       > *TELEPHONE
 User-defined 1 . . . . . . . . . USRDFN1      > 128
 User-defined 2 . . . . . . . . . USRDFN2      > 128
 User-defined 3 . . . . . . . . . USRDFN3      > 128
 Recovery limits:                 CMNRCYLMT
   Count limit  . . . . . . . . .              > 2
   Time interval  . . . . . . . .              > 5

AS/400: Change Ctl Desc (APPC) (CHGCTLAPPC)

 Controller description . . . . . CTLD         > TRUTH
 Online at IPL  . . . . . . . . . ONLINE         *NO
 APPN-capable . . . . . . . . . . APPN           *YES
 Switched line list . . . . . . . SWTLINLST      SHOW
                  + for more values
 Character code . . . . . . . . . CODE           *EBCDIC
 Maximum frame size . . . . . . . MAXFRAME       521

**** Inherited from the SDLC line definition. For best performance, this
setting should match the Max BTU Length setting on the SNA Server SDLC
connection (located under the Advanced settings).

Remote network identifier  . . . RMTNETID       APPN

**** Must match the network name configured on SNA Server (set using Admin
when zooming on the server name), as well as the network name configured on
the Local APPC LU.

 Remote control point . . . . . . RMTCPNAME      TRUTH

**** Must match the local control point name configured on SNA Server (set
using Admin when zooming on the server name), as well as the LU name of the
Local APPC LU.

 Exchange Identifier . . . . . . EXCHID  00000000-FFFFFFFF

**** Must match the Local Node ID on the SNA Server.

 SSCP identifier  . . . . . . . . SSCPID         *SAME
 Initial connection . . . . . . . INLCNN         *ANS
 Dial initiation  . . . . . . . . DIALINIT       *SAME
 Connection number  . . . . . . . CNNNBR         *SAME

 Predial delay  . . . . . . . . . PREDIALDLY     6
 Redial delay . . . . . . . . . . REDIALDLY      120
 Dial retry . . . . . . . . . . . DIALRTY        2
 Switched disconnect  . . . . . . SWTDSC         *YES

**** If this is YES, then the AS/400 will drop the link when there are no
active APPC sessions, so the SNA Server connection should be configured to
activate On Demand. Otherwise, if SWTDSC is set to NO, the SNA Server
connection should be configured to activate On Server Startup.

   Disconnect timer:              DSCTMR
   Minimum connect timer  . . . .                600

**** AS/400 default is 170 sec. AS/400 drops the connection after this time-out when there are no active APPC sessions.

 Disconnection delay timer  . .                  0
 Station address  . . . . . . . . STNADR         C1

**** Inherited from the line description. Must match the poll address
configured in the SNA Server connection (located in the Advanced dialog).

 SDLC poll priority . . . . . . . POLLPTY        *NO
 SDLC poll limit  . . . . . . . . POLLLMT        0
 SDLC out limit . . . . . . . . . OUTLMT         *POLLLMT
 SDLC connect poll retry  . . . . CNNPOLLRTY     7
 SDLC NDM poll timer  . . . . . . NDMPOLLTMR     *CALC
 APPN CP session support  . . . . CPSSN          *YES
 APPN node type . . . . . . . . . NODETYPE       *ENDNODE
 APPN transmission group number   TMSGRPNBR      1
 APPN minimum switched status . . MINSWTSTS      *VRYONPND
 Autodelete device  . . . . . . . AUTODLTDEV     1440
 User-defined 1 . . . . . . . . . USRDFN1        *LIND
 User-defined 2 . . . . . . . . . USRDFN2        *LIND
 User-defined 3 . . . . . . . . . USRDFN3        *LIND
 Recovery limits:                 CMNRCYLMT
   Count limit  . . . . . . . . .                2
   Time interval  . . . . . . . .                5
 Text 'description' . . . . . . . TEXT           'Show controller for Demo
                                                 dial-in.'

AS/400: Change Device Desc (APPC) (CHGDEVAPPC)

Device description . . . . . . . DEVD         > TRUTH03

**** This device name corresponds with the SNA Server Local APPC LU name
(in this case, TRUTH), plus a two-digit device number, generated by the
AS/400 (but not configured in SNA Server).

 Online at IPL  . . . . . . . . . ONLINE         *NO
 Mode . . . . . . . . . . . . . . MODE           *NETATR
                  + for more values
 Message queue  . . . . . . . . . MSGQ           QSYSOPR
   Library  . . . . . . . . . . .                  *LIBL
 Local location address . . . . . LOCADR         00
 Single session:                  SNGSSN
   Single session capable . . . .                *NO
   Number of conversations  . . .
 Locally controlled session . . . LCLCTLSSN      *SAME
 Pre-established session  . . . . PREESTSSN      *SAME
 Text 'description' . . . . . . . TEXT           'AUTOMATICALLY CREATED
                                                 BY QLUS'
 Mode description . . . . . . . . MODD         > QPCSUPP

**** This should not be changed; this is the default mode name for IBM PC
Support clients (and SNA Server).

 Class-of-service . . . . . . . . COS            #CONNECT
 Maximum sessions . . . . . . . . MAXSSN         64

**** This is the number of sessions supported by the QPCSUPP mode, and
should match the SNA Server session limit configured on the QPCSUPP mode
entry, configured using the SNA Server setup program (zoom on Local or
Remote LU, zoom on Partners button, then select the Modes button).

 Maximum conversations  . . . . . MAXCNV         64

**** This should match the MAXSSN setting above.

 Locally controlled sessions  . . LCLCTLSSN      16
 Pre-established sessions . . . . PREESTSSN      0
 Inbound pacing value . . . . . . INPACING       7
 Outbound pacing value  . . . . . OUTPACING      7
 Maximum length of request unit   MAXLENRU       *CALC
 Text 'description' . . . . . . . TEXT           'created by <name>'

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