Conference netcad::hub_mgnt

2329.0. "MOD-PMDs & DECconcentrators" by DELNI::PIEPER () Wed May 31 1995 15:05

    This note is being placed to point out that various DEChub 900 FDDI con-
    centrators which support MOD-PMDs come in many PREPACKAGED options.  
    Future FDDI concentrators will also come this way.  If the lead time on 
    a prepackaged option is very long, check the lead times on the basic con-
    centrator module and the various MOD-PMDs needed to complete the package.  
    If the lead time is small for them, then order the individual components 
    and assemble them in the field.

    The DEF6* product is an FDDI concentrator that has six MOD-PMD front panel
    ports and two backplane ports.  The DEF6X-MA is the basic unit that ships
    with NO MOD-PMDs installed.  The following prepackaged options are or
    were available (some options will retire by Q1):

	DEF6U-MA	6 port UTP concentrator 
			(DEF6X-MA + 6 x DEFXU-BA)

	DEF6A-MA	5 port concentrator (4 multimode + 1 singlemode)
			(DEF6X-MA + 4 x DEFXM-AA + 1 x DEFXS-AA in port #1)

	DEF6B-MA	5 port concentrator (4 multimode + 1 singlemode)
			(DEF6X-MA + 4 x DEFXM-AA + 1 x DEFXS-AA in port #6)

	DEF6M-AA	6 port multimode fiber concentrator
			(DEF6X-MA + 6 x DEFXM-AA)

    NOTE:  If you use the DEFXS-BA single mode MOD-PMD instead of the DEFXS-AA 
	   variant, you can fully populate ALL SIX DEF6X-MA ports instead of 
	   only five as the DEF6A-MA and DEF6B-MA did.

    The DEFHU product has 12 fixed UTP ports plus 2 MOD-PMD ports on the
    front panel (it also has two backplane ports which yield a total of 16
    ports).  The DEFHU-MX is the basic unit that has 12 fixed UTP ports with 
    NO MOD-PMDs installed.  The following prepackaged options are available:

    	DEFHU-MM	12 port UTP with 2 MMF MOD-PMDs 
			(DEFHU-MX + 2 x DEFXM-AA)

    	DEFHU-MS	12 port UTP with 2 SMF MOD-PMDs 
			(DEFHU-MX + 2 x DEFXS-BA)

    	DEFHU-MU	12 port UTP with 2 UTP MOD-PMDs 
			(DEFHU-MX + 2 x DEFXU-BA)
    
        

    Hi,
    
    1) I presume the difference between 
    
       DEF6A-MA        5 port concentrator (4 multimode + 1 singlemode)
                            (DEF6X-MA + 4 x DEFXM-AA + 1 x DEFXS-AA in port#1)
    
       DEF6B-MA        5 port concentrator (4 multimode + 1 singlemode)
                            (DEF6X-MA + 4 x DEFXM-AA + 1 x DEFXS-AA in port#6)
    
       is that you need to choose whether your A and B ports are SMF or
       not?
    
    2) >   NOTE:  If you use the DEFXS-BA single mode MOD-PMD instead of the
       >          DEFXS-AA variant, you can fully populate ALL SIX DEF6X-MA 
       >          ports instead of only five as the DEF6A-MA and DEF6B-MA did.
    
       Could you please explain why this is?  What is the difference
       between the DEFXS-AA & DEFXS-BA?
    
    3) Which packages are to retire?  What's the thinking behind their
       retirement?
    
    
    Thanks,
    
    Clinton

    The DEFXS-AA SMF modPMD used a laser device that was pigtailed --
    that is a single-mode optical fiber was permanently attached to the
    laser. This fiber pigtail was terminated with a connector, which 
    mated with a bulkhead coupler on the bezel. A fiber jumper cable was
    used for the receiver.
    	
    These short fiber cables had to be coiled, but not so tightly as to put
    strain on the optical fibers. These coils gave two problems: air flow
    and space restrictions.  These issues were dealt with by requiring that
    one adjacent PMD slot be unused if the DEFXS-AA were installed.
    
    The DEFXS-BA uses optics with no pigtails, and no jumper cables. It
    can be installed without the restrictions that applied to the DEFXS-AA.
    
    
    Dick Kirk
    Network Product Support