Conference netcad::hub_mgnt

    >> purchase 900MX's to get the FDDI into the hub (same waste of money).
    
    Why is a DEF6X the same waste of money??
    The DEF6X goes for a little over $4K, and a DEFBA goes for a little
    less then $8K. So for about half the price, you can move the DEFBA
    elswhere, buy a DEF6X (with more FDDI flexibility), and then use
    the DECswitch900FO to fan out your 10mb 10baseF fiber.
    The FO was intended to provide bridging capability for FDDI (backplane)
    to 10baseF fiber links where none existed before.
    The FO also provides some inovative configurations when used standalone
    in a DEF1H.
    
    
    Bob

    
    Yes, the DECswitch 900FO is really great in standalone configs since
    you can't use a PortSwitch 900FP + DECswitch 900EF to accomplish this
    in standalone mode.
    
    You won't have this problem with the VNswitch 900FO since this will
    have the optional front panel FDDI.

    re. .1
    
    The MX is ~$7K+ in Canada.  It means you still need 2 modules to
    accomplish what a 900EF and 900FP does.  My customers were sorta hoping 
    to reduce module count in the hub, not keep it the same.
    
    re. .2
    
    I agree you can run a 900FO standalone and get a useful working config
    for the odd customer.  However, with only 1 or 2 exceptions, all my 
    customers run everything in hub.  Only 900TM's with DEFLM's are in 
    standalone configs.
    
    As for a VN900FO, bring it on ASAP as the 900FO won't help any of my
    customers.
    
    Was the FDDI removed/not added to keep costs down??
    
    dave

	I agree that the FDDI out the front would have been more useful.

	Probably the #1 reason for limiting the 900FO to the FDDI BP:

		FDDI out the front would have increased the heat and required 
		more thermal analysis during design.  This would have 
		delayed time to market and the decision was made during 
		design to go with the FDDI BP.

	Bill 

    I hear ya Bill.
    
    Little bit of history... I've got a couple of fans from an old VAX 780,
    cooled the cpu cards, that could be used to keep the 900FO cool.  Mind
    you it's a little hard selling a 20 lb. fan to keep a 1 lb. module
    cool.  Besides it can blow SMD's right off the board.  8^)
    
    dave

    A *naked* MX (i.e. no PMDs) is about 3.5-5k  A POPULATED MX is about
    6k-30K (depending on PMD options, thos SMF PMDs are $$$).
    
    The problem is that if you have a DAS ring hub configuration, using the
    DECswitch 900 as "A" external across backplane to a DECconcentrator and
    out via "B" external - you have a nice failure scenario.  Either
    DECswitch or DECconcentrator can die and you still have connectivity to
    the hub for mission critical stuff.
    
    ANOTHER interesting point is that if you want a point-ta-point for
    DUPLEX FDDI - well you can't do that with an in-hub FO (so you get a
    performance hit).
    
    Those r the constraints about the 900 FO.
    
    However, on the upside, we do have some really nice and dense
    concentrators with the 900TH and 900FH (12 TP and 2 mod PMDS and 12
    fiber with 2 mod PMDs) for only about 7K and 10K respectively.
    
    Now....given that in the bad old days you'd need a:
    
      Portswitch 900FP at about 6k
      DECswitch 900EF at about 8K
    
    You can now do:
      DECconcentrator 900th at about 7K
      DECswitch 900FO at about 8K
    
    ANd for a measely 1K increase you can GIVE your customer (yes I said
    the "g" word - Give") a twelve-fold increase in 100MB connections...
    
    Such a deal...! 
    
    (grin)
    
    Of course, it all depends on the customer needs, configuration, etc.
    
    And, if you're REALLY desperate for some fiber connections, you can
    always do the following kludges:
    
      - DEFLM-AA on the 2 aui ports at about $360
      - Add a DEFMI in the hub for about 1K and put it off the thinwire
        and use switch port 3 for it
      - Add another DEFMI and put it off the first flexlan (which will
        migrate to the upper connector) and take switch port 4 to it.
    
    (all of the above giveyou 4 fiber connects at the expense of only 2
    slots and inner connections...)
    
    Hey, I never said it would be elegant...
    (grinz)
    j

>> FDDI out the front would have increased the heat and 
>> required more thermal analysis during design.

	Actually my early thermal analysis assumed FDDI out
	the front. It showed it could be cooled.

	I believe the choice to limit FDDI to the back was
	based on space (the Ethernet FO take more space than
	the UTP & AUI), or perhaps cost.

				John

    re. .6
    
    Jon,
    
    Glad you're keeping it simple. 8^)  Now if I can only remember suggestion
    number .....
    
    dave
    

    Well, if it were REALLY simple, plug and play, would they need us?
    
    (grin)
    j
    ^--who really does like the configuration options at McDonalds
    
    Would you like that with or without cheese, Dave?