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Conference 7.286::fddi

Title:FDDI - The Next Generation
Moderator:NETCAD::STEFANI
Created:Thu Apr 27 1989
Last Modified:Thu Jun 05 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2259
Total number of notes:8590

708.0. "Receptacle keying" by BAGELS::LEVY () Wed Sep 16 1992 16:18

    Looking for feedback from Field people:
    
    What problems would be caused if all ANSI MIC _receptacles_ in Digital
    FDDI products were keyed S-type?
    
    Clearly, only S-type plugs could be plugged into these receptacles.
    However, since most (all?) FDDI plugs have user-installable keys, it's
    very easy to make a plug S-type (if it isn't already.)
    
    Would your customer(s) have a problem with A, B, and M ports that
    _required_ an S-type plug? Most are probably using S plugs today,
    because they didn't bother installing A, B, or M keys into the plugs.
    The issue raised here is the restriction from using the correct plug
    type. For example, a plug keyed M would not work in a future
    concentrator's M port. Counter-intuitive, yes. However, since plug
    keying is optional, is the whole question moot?
    
    Comments?
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708.1CSC32::B_GOODWINTime is an illusion...Thu Sep 17 1992 09:367
Jon,

I haven't seen any customer use the keying, all the people I have talked
with didn't even know that you could key the MIC connector with the
key provided on the f/o cable.

Brad
708.2One Opinion. DONT DO all S-Ports !!MSDOA::REEDJohn Reed @CBO - DTN: 367-6463 = DNISThu Sep 17 1992 11:5218
    I think that if you are going to key something, then Key the
    concentrator ports  as A,B, and M.  If you suggest keying all of the
    ports the same, (which is what we have already) then what is the use of
    keying them ???  We are trying to avoid A-A, or B-B, or M-M type ring
    misconfigurations right ?  
    
    During installation time, it would be nice to be able to physically set
    up the device ports to only accept properly keyed cables.  But forcing
    all ports to be some random similar keying defeats the idea of keying.
    
    I would vote for user (or installer) configurable keying on the ports
    of controller cards, concentrators, and bridges and routers.  Then when
    we set these things up, it would be less likely for a user to build an
    invalid ring.  Perhaps one version of card could be ordered with
    prekeyed jacks?    Right now, we don't use the keying.  
    
    JR
      
708.3CSC32::B_GOODWINTime is an illusion...Thu Sep 17 1992 12:153
If you should connect a port b-b or a-a, etc, you should get a port
config error led indication so you would know that it is invalid. 
Keying would just make it a little easier to config, if they were used.
708.4installer-configurable keys are comingBAGELS::LEVYThu Sep 17 1992 13:2611
    re: .2
    
    Your input is appreciated. However, based on your comments, I think the
    current situation needs clarification:
    
    Today all Digital products' FDDI receptacles are correctly keyed. (Try
    plugging a B-keyed plug into an M port. It won't work.)
    
    Your request for installer-configurable keying is about to come true.
    The modular PMDs used on NEWPORT, PYTHON, SONOMA, and ONEHUB have
    pop-out keys.
708.5KONING::KONINGPaul Koning, A-13683Fri Sep 18 1992 18:4615
    Well, this isn't a field input.  But it may be something to consider:
    
    The FDDI standard explicitly says that keying of receptacles is
    required.  Of course, there are plenty of products that use ST
    connectors, which aren't keyed.  My impression is that MIC (duplex)
    receptacles are generally keyed currently.
    
    Even if keying has no practical value (which most people agree is true)
    we would expose ourselves to accusations of non-compliance if we don't
    have keys.  It may well be that customers would have the good sense to
    ignore such accusations -- one would hope they would when they realize
    that the keying doesn't actually do anything useful.  But it is a risk,
    though perhaps not a great one.
    
    	paul
708.6Digital's MIC has been supported by customers.TKTVFS::IDONaoki Ido, CSC/TOKYO, EWB, DTN 680-2456Tue Sep 22 1992 02:2510
Jon,

Our customer always use the keys according with the standard. As far as I 
know, most of our local competetors use the mic with solid(fixed) key. 
Customers like DEC's mic style because easy to change the key. Only problem
I've heard the comments from customer is that some keys are loose and easy to
lost away. I think we need the key because it's standard. If we supply the 
mic with only s-type, most of customers think about DEC breaks the standard.

Naoki