Conference netcad::hub_mgnt

2237.0. "FDDI conf and dual home in BP FDDI tree?" by WARABI::CHIUANDREW () Sun Apr 30 1995 23:32

    Hi,
    
    With WAVE 3 DEChub 900 multi-switch new firmware that supports FDDI
    tree in backplane, are the following configurations supported?
    
    Customer would like to build TWO dual FDDI rings within their campus
    because of geographical limitations they have to form TWO dual FDDI
    rings (#1/#2) but would like to interconnect two rings via DEChub900, we
    come up with two alternatives I and II, could someone help to verify
    whether they are 'valid' FDDI configurations? If they are, what are the
    advantages/disadvantages of these two alternatives, if any?
    
    
    Alternative I - using FDDI tree on backplane M-S-M-S
        
    DEChub900 BACKPLANE FDDI tree
    
           !--------------      !-----------------!
         M !             !      !                 ! 
           !             !S     !M                !S
      !--------!    !-------------!    !-----------------!
      !        !    !             !    !                 !
   A -! DC900MX!    ! DC900MX     !    !   DS900MX       !--- 6 Ethernets
      !        !    !             !    !                 !
      !        !    !-------------!    !-----------------! 
      !        !      !       !
    B-!        !     A!       !B
      ---------- 
    
    A/B ports         A/B ports connected 
    connected to      to external dual
    External dual     FDDI ring #2
    FDDI ring #1      (using SMF)
    (using SMF)
    
       At remote DEChub900s, there will be DC900MX and DS900MX to allow 
    SMF FDDI dual ring connections and bridging Ethernets to FDDI rings
    (ring #1 and ring #2) via central hub.
    
    
    
    Alternative II - FDDI tree on BP but dual home at DECswitch900MX
    
    
               !-------------------------------------!
             M !                                     !
               !                                     !S
          !--------!    !-------------!    !-----------------!
          !        !    !             !    !                 !
       A -! DC900MX!    ! DC900MX     !    !   DS900MX       !-- 6Ethernets
          !        !    !             !    !                 !
          !        !    !-------------!    !-----------------!
          !        !      !       !  !M           !S
        B-!        !     A!       !B !            !
          ----------                 !-------------
    
        A/B ports         A/B ports connected
        connected to      to external dual
        External dual     FDDI ring #2
        FDDI ring #1      (using SMF)
       (using SMF)	
    
    
    
    	With these configurations, could devices on ethernets of DECswitch
    900MX access to either FDDI rings via the DS900MX/DC900MXs?
    Customer wants SMF between sites so we have to use DC900MXs and use it
    to interconnect two FDDI rings.
    
    
    thanks for any comment/idea.
    Andrew Chiu - Network Services Sydney

    I am confused by your drawing.   You indicate a CONCENTRATOR with "S"
    ports, which I have not seen before.
    
    Do you really need TWO FDDI rings, or are you just trying to cover a
    large distance, and wish to use SMF in part of your campus ring?
    
    Digital does not have an FDDI/FDDI bridge or router.  So you CANNOT
    join two separate rings using the existing HUB-based products, without
    using some external product such as the Gigaswitch, or DECNIS.
    
    If you just wish to use SMF, and cover large distances, just use a
    modPMD with SMF in the Hub module A or B port which needs only ONE FDDI
    RING, but different types of fiber between some stations.
    
    Example:
    
    Left campus
    
    conc with SMF pmd in "B" port             conc, with SMF in "A" port
    [AMMMMMMB]					  [AMMMMMMB]  Hub Conc
     \      \                                     /       +
      \___   \=====single Mode===================/        +
          \                                              +backplane
    conc   \                                            +
    [AMMMMMMB]                                         [AB] Hub Bridge
     \                                                   +
      \                                                   +
    [AB] bridge  (with SMF modPMD in "A" port            [AMMMMMMB]
     \======single mode==========================================/
    
    
    I would attach the long haul SMF sites to AB ports on your main hubs,
    using a SMF modPMD in the "A" of one module, and "B" of the exit module
    and dual-home your short-haul sites (A+B to M of different
    concentrators) to the top level hubs.   You don't need two rings,
    unless the traffic level will be really high, or they wish to have
    isolation between them.  Sounds like a big site.  Good luck
    
    
    JR

    
    I agree with most of what John offered in .1, but there is 
    a mistake in the drawing, if the bridge in the lower left 
    of his drawing is a 900EF in a hub. If the bridge is a DECBridge 
    600 series, or, a 900EF in a docking station, it will be OK. The 
    900EF only has multimode ports when in a hub. 
    
    Also, the alternatives that Andrew sketched cannot be built with
    the hub modules. If John's suggestions aren't suitable for the
    customer, put a note here, and I'll try to answer it. The total
    distance, when the ring is wrapped can be as high as 200km, in 
    case that helps with solving your SMF proble. 
    
    We will very shortly be upgrading note 1597 to include the 
    rules for trees in the hub. Stay tuned......