Conference 7.286::fddi

869.0. "Copper FDDI Standards Update" by LEVERS::B_CRONIN () Mon Feb 22 1993 15:01

    The FDDI standards committee met last week, and here is an update on
    the TP-PMD work. 
    
    The committee chose 2.0 V p-p as the UTP transmit voltage. Testing 
    shows that this should give Class B radiated emissions performance 
    and 3 V/m susceptibility performance when the cables are properly 
    terminated. STP work is continuing.
    
    The committee also chose to place the crossover in the cabling, rather
    than in the MIC. This was done because FDDI supports 4 connection 
    types (A,B,M,S). No matter how hard you try, you always need two kinds
    of patch cables if you try to eliminate the need for crossovers in the 
    cabling. There had been proposals for A, B, and S connectors to have 
    one pinout, and M connectors to have a different pinout. This would 
    have allowed ALL straight through cabling for M-S connections, but not
    for A to B, S to S etc. 
    
    NOTE: The above means that one patch cord has a crossover in it, but 
    the other patch cord, and the cabling in the wall will be staright through. 
    It DOES NOT mean that FDDI requires you to change the way that EIA/TIA 568 
    says to wire the connection from the office wallplate to the patch panel 
    in the wiring closet. Which patch cord gets the crossover can be left
    to the local network administrator. From the simplest point of view, if
    the crossover cable is given to the user, then any connection the user
    makes will work correctly. 
    
    I'll spare you the additional details of committee life, but, progress
    was also made on a couple of other details. 
    
    I will not hazard a guess on a completion date, but I think I can see
    faint light at the end of the tunnel (and it isn't a train).