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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

1198.0. "Thinwire/UTP Balun?" by DPDMAI::DAVIES (Mark, SCA Area Network Consultant) Sat Jan 08 1994 11:56

    I have a very large ethernet customer who took Digital's advice and
    wired their building with thinwire as opposed to UTP.  They are now
    going to begin upgrading many desktops from ethernet to FDDI.  Many of
    their desktop systems are NOT made by Digital.  They are having trouble
    finding vendors besides Digital that makes thinwire FDDI adapters.
    
    They need a resolution within 90 days.  resolution means one of the
    following:
    
    	1. Find Thinwire adapters for SUN, HP, RS6000.
    
    	2. Find a thinwire-to-UTP balun for FDDI use.
    
    	3. Begin the task of replacing their Digital recommeded cableplant.
    
    It appears that #3 is the answer.  Does anyone have any information
    which could help us not have to do damage control here?
    
    Thanks,
    
    Mark
T.RTitleUserPersonal
Name		DateLines
1198.1rewire w/ cat 5LEVERS::MELARAGNISat Jan 08 1994 14:3627
    Well, you've hit a sore spot with that one. Thinwire FDDI sales have
    been less than stelar over these last 3 years and because of this we
    have stopped development of new Thinwire devices. DEFZAs and DEFCNs
    are the only two products that i know about that actually implement the
    Thinwire solution. I don't think DEFTA implments Thinwire, but it
    might.
    
    You have a real problem on your hands. The balun idea is nice, but it
    won't work for UTP cable lengths over 30 of 40 meters. Thinwire cable
    is actually a VERY good cable in that its bandwidth is quite high. Much
    higher than the same length Cat 5 UTP. Since the bw of Thinwire is so
    high, no special TX encoding or RX equalization was put into the
    thinwire adapters. UTP cable put into the place of Thinwire will
    perform miserably unless the RX performs adaptive equalization --
    something that is unique to TP-PMD. A balun is not the solution. 
    
    At last check, our Thinwire solution was proprietary -- no other
    vendors supported it. Chances of you finding adapters for
    non-turbochannel busses are low.
    
    The only real solution is to rewire w/ Cat 5 cable. I know your
    customer will bitch up a storm, but there really isn't any other
    workable option.
    
    Sorry for the bad news.
    
    bill
1198.2FYILEVERS::B_CRONINMon Jan 10 1994 11:0314
    
    Mark,
    
    Just as an FYI - Digital offered to license the Thinwire FDDI
    technology. I personally conatcted many people - NO ONE wanted
    to even discuss terms. The lack of products isn't because 
    we didn't try to make it happen. 
    
    Bill
1198.3EMESOH::SCHULTZLittleton Bound !!!!Mon Jan 10 1994 19:047
    
    Had we told them to use UTP, they probably would have installed Level 3
    cable anyway and would still need to upgrade to level 5.
    
    Sometimes you just can't win.....
    
    MTS
1198.4Thanks for the help.DPDMAI::DAVIESMark, SCA Area Network ConsultantTue Jan 11 1994 12:3923
    Thanks for the responses.  For many years Digital pushed Thinwire over
    UTP.  For many years this was an excellent decision.  When UTP came, in
    most cases, Digital folks were instructed to continue to push Thinwire.  
    
    Thinwire has the same problem that Digital MMJs have/had:  They are
    closed solutions.  MMJs are obviously closed and Thinwire doesn't
    support token ring, which means the customer is locked into ethernet.
    
    RJ45s and UTP and Fiber are open.  For many years customers looked at
    Digital and some of our solutions and just laughed.  Not all, but those
    who wanted to leave themselves with many options in the future.
    
    Anyways, industry standards sell well, the rest of them are still up to
    the market place (ie, OSI).
    
    Lots of opportunities for our products now that we recognize the above
    and TCP/IP, SNMP and other open solutions.  Now we just need to spend a
    few years rebuilding our credibility.
    
    Regards,
    
    Mark