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Conference netcad::hub_mgnt

Title:DEChub/HUBwatch/PROBEwatch CONFERENCE
Notice:Firmware -2, Doc -3, Power -4, HW kits -5, firm load -6&7
Moderator:NETCAD::COLELLADT
Created:Wed Nov 13 1991
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:4455
Total number of notes:16761

2066.0. "SMF MOD PMD (DEFXS) problems" by BRIEIS::BARKER_E (test dummy) Thu Mar 02 1995 15:36

    Hi,
    
    I'm looking for some advice. A customer has ordered a DEF6X-MA
    (DECconcentrator 900MX with no PMD's) and then ordered a number of MMF
    PMD's and one SMF PMD to be fitted. I turned up on site to configure an
    FDDI ring , got presented with this so had to go ahead and fitted
    them...
    and the SMF module didn't operate correctly. I was incredibly careful
    with the fibre loops etc, honest ! We tried another DEFXS-AA today and
    that gives the same problems. Is there any testing that can be done on
    the concentrator and DEFXS-AA or is the next stage to a/ try DEFXS in
    another concentrator and b/ swap the concentrator ?  Seriously, I
    didn't exceed any bend radius' not already in the packaging and tried
    to ease out the cable to as large a radius as possible, one problem was
    that the way they are packed the fibre seems to get a memory for being
    bent one way in the packaging and although we had two free slots next
    to the SMF PMD this still made life awkward.
    
    	Thanks for any pointers and advice,
    
    		Euan
T.RTitleUserPersonal
Name		DateLines
2066.1NETCAD::B_CRONINThu Mar 02 1995 16:497
    
    Can you connect a single mode fiber as a loopback connection on 
    that one SMF port? If the module is good, the loopback connection should 
    result in a blinking yellow light, indicating that the connection is 
    being rejected (because of a topology reject). That will tell you if
    the module is dead.
2066.2BRIEIS::BARKER_Etest dummyFri Mar 03 1995 06:3217
    Hi,
    
    	Thanks for the reply, I can try that but I will have an issue with
    the minimum length for the loopback due to the inline loss on a short
    cable, the customer has no inline loss elements as far as I'm aware.
    I'll patch around the full length of the ring on one core which will
    total 22km.
    
    	I have a suspicion the customer may have tried the above with 10m
    SMF patch cables directly between two concentrators. What would this
    do, destroy the DEFXS MOD PMD ?
    	
    	Thanks,
    
    		Euan
2066.3Could be a general db loss issue ?BRIEIS::BARKER_Etest dummyFri Mar 03 1995 07:3921
    Hi,
    
    	MMmmm, this is leading somewhere, the loss adjuster issue in .2 got
    me thinking, phoned the customer and guess what, the db loss on the
    circuits is 4.2 on one (plus whatever 2 patch cables introduce) and 6.8
    on the other (plus whatever 5 patches inroduce).  The 6.8 plus 5
    patches route is the one that is working, the 4.2 one isn't.  What is
    likely to happen to the DEFXS-AA in this situation ?
    
    	This could get sticky, we (as a project team) specified the ring
    must be available and operative before we got on site, and once there
    assumed it matched our required spec. It is running in
    parallel with a Cisco network on the same fibres and having talked to
    the Network Manager they didn't check the db loss we require. It is
    about to be tested. Anyone know of the Cisco kit would specify a db
    loss range different to ours of 12-22 db or is 12-22 a standard spec. ?
    
    	Thanks again,
    
    
    	Euan
2066.4You need those attenuators!NPSS::KIRKFri Mar 03 1995 08:2718
    If the cable plant has less than the required 12 dB loss, the FDDI link
    will not come up. The DEFXS-AA will not be damaged.  When you get an
    in line loss element (3m makes a good attenuator -- costs about $30)
    in place, the same DEFXS-AA module should work just fine.
    
    I think that the CISCO SMF module is designed with a different loss 
    budget. If they designed to meet the Category 1 levels of the ANSI
    SMF PMD, then they will not need any minimum loss in the cable plant.
    If that is the case, then their maximum distance is likely to be less
    than that of the DEFXS-AA.
    
    Please let me know if you have trouble locating attenuators. I will
    forward you a partial list of vendors.
    
    
    Dick Kirk
    Network Products Support
    (Fiber Optics a specialty)
2066.5Sussed !BRIEIS::BARKER_Etest dummyFri Mar 10 1995 04:497
    Dick,
    
    	Yep, some testing by looping the ring through one site and back to
    the other proved the kit was all OK. One attenuator later and we have a
    fully working ring. Many thanks for all the help,
    
    	Euan
2066.6Great job!NPSS::KIRKFri Mar 10 1995 08:423
    I'm glad you have succeeded. 
    
    Dick