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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

1571.0. "question on lenght of MMF cable" by HERON::ERBES (Milan - Lala iz Juznog Banata!) Fri Feb 03 1995 03:20

I have a question that relates to length limitations to usage of repeaters on 
multi mode Fiber Cable installations.

As I understand it we are limited to 2000 meters (our standard) for multi mode 
cable.  If we were to exceed this length up to 3000 meters (using this cable) 
without placing ANY repeater in that span of fiber what product would we need
instead of a Digital DECREPEATER 90 or 900?

Customer needs to use fiber that will be placed on a cable tray which will 
run through a plant. The 3000 meter placement of the cable will be unaccessible 
to personnel and getting power to points where repeaters could be installed 
would be difficult and costly.

Are there any new Digital Repeaters that could be used? 

Cabletron has such repeater. (Formim-22 and FOT-F14/F24/F25)

Need for this information is relatively urgent. If anyone can help it will be 
greatly appreciated. 

Many thanks in advance,

Best Regards,

Milan Erbes
T.RTitleUserPersonal
Name		DateLines
1571.1Ethernet Bridge or FDDI SMFNPSS::KIRKFri Feb 03 1995 08:4914
    Is this for FDDI or Ethernet?  IF it is Ethernet, you may run into some
    timing restrictions, and a bridge would be recommended. We used to sell
    a bridge with an option that work allow up to 10 km fibe links. I don't
    know if it is still available - Product name was DEBAM, with a
    DECPI-AF interface.
    
    If your application is of the FDDI type, 3000 meters could be achieved
    with single-mode options.  Or if the cable loss and bandwidth
    characteristics are just right, you might be able to squeeze 3000
    meters.
    
    
    Dick Kirk
    Networks Product Support
1571.2yes, they use ethernetHERON::ERBESMilan - Lala iz Juznog Banata!Mon Feb 06 1995 03:376
Dick,

thanx for the clarifications! Yes they use ethernet, so they'll go with the
bridge!

Regards, Milan
1571.32 more centsSTOWOA::PERLMUTTERMon Feb 06 1995 14:4711
    hi milan
    
    the 2000 meters comes from the 10BaseFL spec. I don't beleive that you
    can violate this safely. Maybe cabletron is using some kind of
    proprietary signalling method and in my believe this approach would be 
    outside of the 802.3 specification.
    
    if you don't have single mode fibers I would source some fibre optic T1
    modems and use serial bridges on this link.
    
    if I had single mode optics I would use an FDDI.
1571.4HERON::ERBESMilan - Lala iz Juznog Banata!Tue Feb 07 1995 09:039
Salut Bruce!

Nice to hear from You!

Thanx for the info, I'll pass them to the customer!

All the best from old nice Cote D'Azur

Milan