Subject: DLUR Architecture Change Proposals Now Available For Review

From: "Ed Tremblay (254-5515)" <[email-masked]>
Date: Fri, 21 Jul 95 13:45:35 EDT

Proposals to change the APPN DLUR Architecture Reference manual have
been placed on networking.raleigh.ibm.com for items 8296 and 8303.
The files can be found in directory /aiw/dlur:

     abs8296.txt
     abs8303.txt
     arch8296d.psbin
     arch8303d.psbin

The individual items are as follows:

8296) Clarify DLUR EN tail vector registration processing

      Questions from DLUR implementers concerning DLUR EN tail vector
      registration procedures have pointed out a need to specify in the
      DLUR architecture document the algorithm for DLUR to use to decide
      which session (CP-CP or CP-SVR) session to use to send TDUs.  The
      algorithm needs to take into account:

         * session outages
         * preferred sessions activating after not-so-preferred sessions
         * initial and subsequent TGV registration
         * adjacent and non-adjacent DLUR/DLUS pairs

      It turns out that VTAM handles the TDUs the same whether they are
      sent over the CP-CP session or the CP-SVR pipe.  Therefore, this
      item will also optionally allow the adjacent DLUR to not use the
      CP-CP session and only use the CP-SVR pipe for tail vector
      registration (an option that many implementers have requested).

      This clarification includes updating the "DLUR EN Tail Vector
      Registration" section of the DLUR Architecture Reference to
      include the following algorithm for DLUR to follow to determine
      which session (CP-CP or CP-SVR) to use to send TDUs:

         1) at initial TGV registration,

              a) if the DLUR and the DLUS are adjacent, and if the DLUS
                 supports receipt of TDUs (indicated in the CP
                 Capabilities X'12C1' GDS variable, then the DLUR may
                 optionally send the TDUs over the CP-CP session
                 between the two nodes

              b) otherwise the TDUs will be sent over the CP-SVR pipe
                 to the DLUS node

         2) if the CP-SVR pipe is selected for initial registration:

              a) continue to use it for subsequent TGV registration even
                 if a CP-CP session between adjacent DLUR and DLUS is
                 activated later

              b) if the CP-SVR pipe fails, once the pipe is reactivated
                 (to either the same or a different DLUS), return to
                 step 1) and send all tail vectors

         3) if the CP-CP session is selected for initial registration:

              a) continue to use it for subsequent TGV registration

              b) if the CP-CP session fails, return to step 1) and
                 send all tail vectors

              c) if the CP-SVR pipe fails, once the pipe is reactivated
                 (to either the same or a different DLUS), return to
                 step 1) and send all tail vectors

8303) Allow signaling information definition at DLUR

      DLUR signaling information is currently defined via DLCADDR
      at the DLUS.  While some users prefer centralized (at DLUS)
      signaling information definition, there are others who prefer
      distributed (at DLUR) definition.  The DLUS does not require
      DLCADDR to be defined, so some or all of the information
      currently defined via DLCADDR at the DLUS should be allowed to
      be optionally sysdefed at the DLUR instead.

        * DLUR-initiated SSCP-PU activation
          ---------------------------------
          It appears that the DLUR already has the signaling
          information it needs when it builds REQACTPU.  If this is
          true, it shouldn't be necessary to:

             - define the same signaling information at the DLUS
             - send the same signaling information with ACTPU

          DLUR can send the signaling information with REQACTPU; the
          DLUS uses it for:

             - network management
             - CSX user exit for connection verification and accounting
             - internal PU correlation

        * DLUS-initiated SSCP-PU activation
          ---------------------------------
          If the DLUS only has partial signaling information defined,
          it does not affect:

             - network management
             - CSX user exit for connection verification and accounting
             - PU correlation

          Some, if not all, of the signaling information defined
          at the DLUS via DLCADDR could be optionally defined at
          the DLUR.

      The proposed solution is to update the DLUR architecture
      reference as follows:

      Signaling Information - This parameter will identify the
      DLUR-to-PU connectivity.  This information must be coordinated
      between the DLUR and DLUS nodes:

        1) it can be defined completely at the DLUR - in this case some
           or all of the information can optionally be sent to the DLUS
           to be used for network management, input into the
           Configuration Services XID exit for connection verification
           and accounting, and PU correlation

        2) it can be defined completely at the DLUS - in this case
           all of the information will be sent to the DLUR on the ACTPU

        3) it can be defined partially at the DLUS and partially at the
           DLUR - in this case the DLUR can optionally send the
           DLUR-defined signaling information (for the reasons described
           above) while the DLUS-defined signaling information will be
           sent on the ACTPU

             - if upon receipt of the ACTPU, the DLUR determines it has
               incomplete signaling information, it can optionally
               proceed with the activation (using defaults) or it can
               fail the activation

             - if upon receipt of the ACTPU, the DLUR determines it has
               duplicate signaling information, it will use the values
               sent by the initiator of the activation

I'm requesting approval of these items at the next AIW in August during
the APPN Reference SIG session.

Ed Tremblay