Conference 7.286::fddi

      Scott
    
      Please see my earlier note 561 re: some of the LAT problems we've seen on 
      a recent FDDI installation (for an MDF cluster).
    
      My understanding from UK Country/Product Support is that using LAT over 
      two controllers onto the same extended LAN is not supported due to the 
      way LAT works (or is written)....  We also discussed the idea of a LAT 
      failover situation and apparently it doesn't work. I think the first LAT 
      circuit address defined to the system is "remembered" so if it goes away 
      the second circuit can't/wont be seen anyway, or at least not properly. 
      (Steve Woodward may be able to expand here - he did the "research". I'll 
      give him a nudge to add his findings here).
    
      Our MDF customer tried running LAT over both adapters for a short while - 
      with no problems seen I might add. However, until I get an answer as to 
      whether this configuration is supported I have asked him to set the 
      system to use the FDDI device only. This latter configuration cleared up 
      the problems we were experiencing and described in note 561.
    
      Looking forward to seeing some other answers to your queries.
    
      Regards
    
      Rog

      Scott
    
      I've just spoken with a contact about the LAT over multiple adapters 
      issue...
    
      I'm told that a while ago LAT did have this functionality to failover  
      between multiple adapters which worked quite well. However, more recent 
      version(s) of LAT have somehow affected this capability so that it 
      doesn't work as well. You can run LAT over multiple adapters but there is 
      now no "hot failover" capability.
    
      Also, LAT running over multiple adapters on the same LAN is officially 
      NOT supported. (It is OK over separate LANs).
    
      However, it is not as serious as I initially understood to change the 
      LAT service between adapters. ie. Stop LAT, re-define the LAT$DEVICE to 
      the "new" adapter and restart LAT again - not a reboot as I had been led 
      to believe.
    
      A future release is intended to regain the functionality lost in the 
      recent versions - timescales/version numbers unknown at present.
    
      Hope this helps
    
      Rog

    
    	I have put in a note to my favorite LAT engineers to spell
    out for us exactly whats what right now... I have a couple
    suggestions:
    
    	1) This is probably better addressed in a LAT/LATMASTER note
    	   conference,.. but I don't have a pointer. (thats one of
    	   the things I asked for)
    
    	2) There is sufficient confusion given the information is
    	   LAT and possibly VMS version dependent. I think the
    	   answers to these questions really will take the form
    	   of a truth table,.. where certain combinations can support
    	   and others can not.
    
    	So,.. with all due respect, I'd like to get the straight scoop,..
    from product engineering. Unfortunately, the Engineer is on vacation
    	this week,.. but I hope to have something in here next week.
    	I know that doesn't help you now (sorry),.. and I'm not sure
    	how much experimentation you want to do, or are able to do.
    	If its a customer thats already hot,.. don't antagonize by 
    	experimenting too much until we get an idea of exactly which
    	combinations "ought" to work...
    
    
    	On the other hand, if this is pre-sales activity,...
    
    							/Bill
    

thanks for the response.  I have cross-posted in 
noted::lat  #4137.0

		... scott