Conference netcad::hub_mgnt

I do not understand your picture.  It appears that your customer is trying 
to make two SAS connections (possibly dual-homing?) as opposed to a dual ring
connection.  Why is the customer not using a dual ring configuration?

Also we need more detail than just the following:

                    DECHUB		    DECHUB
                    M-  -A                 A -   -M
                       -   -              -    -
    			 A-  M- DECHUB -M   -A


Is there only one DB 900MX per hub or are there multiples.  EXACTLY what 
FDDI devices in the hubs are the FDDI M and A ports on?

The following configurations (assuming only ONE DECbridge per DEChub) would 
work:


	DUAL RING SOLUTION:

		+-----------+			+-----------+
		| DEChub #1 |			| DEChub #2 |
		|	    |			|	    |
		|  DB900MX  |			|  DB900MX  |
		+-+-------+-+			+-+-------+-+
		 A|	  |B			 A|	  |B
		  |	  +-----------------------+  	  |
		  |					  |
		  +---------------+       +---------------+
				 B|	  |A
				+-+-------+-+		
				|  DB900MX  |	
				|	    |	
				| DEChub #3 |	
				+-----------+



	DUAL HOMING SOLUTION:

		Note that this solution REQUIRES a DECconcentrator 900MX
		in DEChub #3 and ALL connections (including the DECbridge
		to DECconcentrator in DEChub #3) MUST be made across the 
		FRONT panel ports (in other words NO backplane connections
		since "tree" connections in the DEChub backplane are NOT 
		yet supported by the firmware)

		+-----------+			+-----------+
		| DEChub #1 |			| DEChub #2 |
		|	    |			|	    |
		|  DB900MX  |			|  DB900MX  |
		+-+-------+-+			+-+-------+-+
		 A|	  |B			 A|	  |B
		  |	  +-----------+ +---------+  	  |
		  |		      |	|		  |
		  +-----------------+ | | +---------------+
				    | | | |
			    +-----+ | |	| | +------+
			    |     | | | | | |
			    |	+-+-+-+-+-+-+-+	   |	
			    |	|   DC900MX   |    |
			    |	|	      |    |
			    |	|	      |    |
			    +---+   DB900MX   +----+
			       A|	      |B	
				|  DEChub #3  |	
				+-------------+


Remember that DUAL RING connections are the ONLY connections that are currently
supported across the DEChub 900 backplane.  This means that any attempt to 
support a "tree-type" configuration (including dual homing) CANNOT be done
across the DEChub backplane.  Dual homing and treeing can be accomplished via
the FRONT PANEL ports ONLY (ie B-port connecting to M-port, A-port connecting
to M-port).  Today the DECconcentrator is the only device that supports M-ports
so any attempt to tree REQUIRES EXTERNAL CONNECTIONS to a concentrator.

    
    My customer at Pratt Whitney is trying to do this ... will HUBwatch
    v3.0 support this ... if so ... can someone explain how ... the doc is
    not straight forward 
    
    any help 
    
    -Charlie 

	Your configuration doesn't make sense for a 2 reasons:

	1-) It looks like you have 2 concentrator modules in a hub with their
            B ports on the back.  You can't connect them together.  B-B doesn't
	    work.

	2-) You have A-M,M-A in one concentrator and A-M,M-A in the other.  That
	    is a master-slave loop.  THAT IS BAD!  FDDI can't prevent that, the
            user has to prevent that (the proof of why this is bad is complicated.
            Let's just say you can end up with more then 2 rings...)

	Luc
            

    Thanks for the replies, sorry the picture is so vague.  It sounds like
    dual SAS cannot work.  The customer was looking for redundancy, if the
    SAS connection failed then the second would be available.  The
    configuration that I am going to recommend is the DAS in a ring.  I will 
    tell the customer that if they wish to use a star (point to point) 
    configuration then only one SAS connection to the remote hub can be used 
    (DC900 M port to remote DB900 A or B port).
    
    Thanks,
    	Ted  
    
     

    
    You can do front panel dual-home connections, just not the way you were
    trying to do them.  You need to connect the A and B ports on the bridge
    to M ports on Concentrators - the B will be active, and the A wiil be a
    standby.  For better redundancy the M ports should be different hubs,
    connected via A-B connections in a dual ring.
    
    You can't do dual-home connections on the backplane yet.
    

    Thanks,
    This is what the customer has accepted and will work well.  
    
    Ted