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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

277.0. "SMF VERSUS MMF - Way to go??!!" by SIOG::ODRISCOLL (Step to the Music ye Hear) Tue Jun 11 1991 15:17

    Folks,
    
    I'm confused. My customer would like to run 10mb Ethernet over Fibre
    between two buildings about 6km apart. He wants to achieve unattended
    operations in the second site. Later he plans to utilise FDDI when things 
    start appearing within VMS to support it. He would like to preserve his 
    investment in fibre.
    
    I'm told that the LANbridge 200s will only support Multi-mode fibre and
    that to get that type of distance in FDDI would require single mode
    fibre which means he will not get any investment protection in
    fibre!!??!
    
    Is this correct? Any other suggestions?
    
    Thanks,
T.RTitleUserPersonal
Name		DateLines
277.1Pull both!OTOO01::WATKISSThe BLeading Edge of Technology!Tue Jun 11 1991 17:1511
    Yes.
    
    However, when you look at the individual fiber cost versus the cost of
    installing the cable plant he will still be ahead pulling in a cable
    that has both multimode and single mode fibers. Terminate the multimode
    today and leave the single mode dark until he needs it. This will incur
    a relatively small incremental cost for the migration capability.
    
    Regards,
    
    Terry
277.2Another optionLARVAE::HARVEYBaldly going into the unknown...Wed Jun 12 1991 10:2725
   
   	 Not knowing the current (if any) investment in Fibre Ethernet 
         components - like Chipcom etc. - this may be wide of the mark !
   
   	 To save buying (say) Chipcom fibre products now and FDDI later why 
         not consider/propose the use of FDDI as a backbone between the 2 
         sites Ethernets.....
   
   	 ie. Ethernet -> 10/100 Bridge -> Concentrator -> 6 Km Single Mode 
         Fibre  -> Concentrator -> 10/100 Bridge -> Ethernet
   
   	 This XLAN would support the mode of (Ethernet) operation the 
         customer wants to maintain for a while and provide a ready-made path 
         for full FDDI usage later with little or no wastage of 
         kit/investment.
   
   	 It just occurred to me that the Ethernet/FDDI Bridges recently 
         announced capability to act as Dual Attach Stations may allow for 
         the Concentrators to be deferred to a later date - saving yet more !
   
   	 I'd better stop now before I kill the sale altogether huh ?! ;-}
   
   	 Hope this helps
   
   	 Rog
277.3ODS MMF-SMF converter boxes.MADMXX::C_OUIMETTEWampeters and FomaWed Jun 19 1991 10:0510
    	One more possibility... I've got a customer using a MMF to SMF
    converter box from ODS to connect 2 F.O. DEBAMs over SMF. Not supported
    by DEC (I don't believe that ODS products are listed in the VES book,
    but I could be wrong), but it works. I believe there's been some
    discussion of this in the LB100 conference, take a peek in there for
    more info on ODS. You would need to price it out & compare it against
    pulling dual fibers, as suggested in .1...
    
    					chuck