(Item 8343) DLUR redriving SSCP-PU activation after receiving DACTPU            
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There is a problem with DLUR connected devices, where the                       
attaching device is also a type 2.1 node with independent sessions.             
                                                                                
The scenario is a CM/2 attached via a single link to a 950 DLUR. The            
device is connected into the 950. No CONNOUT from VTAM was permitted.           
                                                                                
When VTAM DACTPUed the device PU, the 950 DLUR also inactivated the             
connection between the DLUR and the CM/2, killing CP-CP sessions and            
LU-LU sessions.  The reasoning was that there was no other means to             
cause the CM/2 to re-enable its SSCP-PU session, since no "connout"             
capability was coded in VTAM.                                                   
                                                                                
There is agreement that the 950 should NOT deactivate the                       
connection.  Instead, when a DACTPU is received at the DLUR for a               
downstream PU, if the DACTPU is not the result of a previous REQDACTPU,         
and the original connection was established via REQACTPU, then the DLUR         
will immediately send a REQACTPU back to the DLUS. This will redrive            
the connection and reestablish the SSCP-PU session while not impacting          
other sessions.                                                                 
                                                                                
The current proposal is as follows:                                             
                                                                                
                 ------------------------                                       
                 ! DLUR receives DACTPU !                                       
                 ------------------------                                       
                            !                                                   
              --------------------------------                                  
             ! result of previous REQDACTPU ? !                                 
              --------------------------------                                  
                   ! N                   ! Y                                    
      ---------------------         -----------------                           
     ! original connection !        ! Link Outage ? |                           
     ! sent by REQACTPU ?  !        -----------------                           
      ---------------------            !Y         !N                            
         ! Y            ! N        Clean up    --------------                   
 ---------------------  !-------!  everything  ! PU outage? !                   
 ! DACTPU(giveback)? !        -----            --------------                   
 ---------------------        ! A !             !Y       !N                     
     ! Y        ! N           -----   Clean up PU/LU   Discontact PU            
     !     -----------------            sessions       Clean up PU/LU           
     !     ! send REQACTPU !          Keep link up       sessions               
     !     ! to same DLUS  !            unless ...     Keep link up             
     !     -----------------            (see A)          unless...              
     !                                                   (see A)                
 --------------------------                                                     
 ! Active LU-LU sessions? !                                                     
 --------------------------                                                     
    ! Y               ! N                                                       
-----------------   -----                                                       
! Send REQACTPU !   ! A !==> Clean up SSCP-PU/LU sessions                       
! to other DLUS !   -----    Retain LU-LU sessions if DACTPU type and           
-----------------            ANS allow it                                       
                             Keep link up unless link type requires it          
                             (e.g., short hold mode                             
                                    limited resources                           
                                    maybe switched with all link                
                                    stations inactive)