(Item 008459) Update EN DLUR Tail Vector Registration processing                
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During the review of item 8445 (update DLUS processing for setting              
receipt of TDUs support) at AIW13, a consensus was reached recommending         
the EN DLUR tail vector registration section be updated.  The change is         
to direct the EN DLUR to register or not register its tail vectors with         
a DLUS in its subnet depending on the DLUS's setting in the DLUR/S              
Capabilities control vector of the indicator for support of the                 
RECEIVE_TDU_TP (X'22F0F0F4') service transaction program.                       
                                                                                
Since the AIW, there has been a question about how the DLUR decides             
whether or not the DLUS and DLUR are in the same subnet.  NETIDs cannot         
be compared since more than one subnet can have the same NETID, and             
casually connected ENs can have a different NETID than the rest of the          
nodes in the same subnet.  The mechanism to determine same or different         
subnet should also be included in the EN DLUR tail vector registration          
section.                                                                        
                                                                                
The proposed solution is to update the DLUR/S architecture (section             
8.2, "DLUR EN Tail Vector Registration"), adding:                               
                                                                                
   The EN DLUR can determine whether or not it is in the same subnet            
   with the DLUS by examining the Locates it receives during CP-SVR             
   pipe activation, either:                                                     
                                                                                
     - the Locate sent by the DLUS to activate its conwinner CPSVRMGR           
       session, or                                                              
                                                                                
     - the Locate reply sent by the DLUS in response to the Locate              
       sent by the DLUR to activate its conwinner CPSVRMGR session              
                                                                                
   In the Intersubnetwork Search (X'82') Locate control vector there is         
   an intersubnetwork TGs crossed count:                                        
                                                                                
     - if the count is zero, the DLUS and DLUR are in the same subnet           
                                                                                
     - if the count is nonzero, the DLUS and DLUR are not in the                
       same subnet                                                              
                                                                                
   An EN DLUR in the same subnet as the DLUS will register or                   
   not register its tail vectors dependent on the DLUS's setting in             
   the DLUR/S Capabilities control vector of the indicator for support          
   of the RECEIVE_TDU_TP (X'22F0F0F4') service transaction program              
   (see section 8.2.1 for more information about when the DLUS will             
   set the indicator):                                                          
                                                                                
     - if the indicator is off, the EN DLUR will not register its               
       tail vectors                                                             
                                                                                
     - if the indicator is on, the EN DLUR will register its tail               
       vectors