Conference 7.286::fddi

254.0. "Wellfleet Crash w/ VOID Frames" by ZPOVC::LESTERYUNG (T&N Mkt/Asia Region) Thu May 09 1991 06:21

    Just want to share an experience a customer had when connecting a
    Wellfleet router with a DEC concentrator on the same primary FDDI ring.
    
    On a ring of less then 2Km, the Wellfleet router shut down because it
    could not handle the number of VOID frames being produced by the DEC
    Ring Purger in our concentrator.
    
    When the ring was increased to 2Km, the Wellfleet router worked OK.
    
    Now the customer precieved the problem to be DEC's implementation of the
    Ring Purger which is not specified in the SMT 6.2 spec. and is in fact
    an added value feature of our FDDI products.
    
    Our FDDI engineers looked into this precieved problem and discovered it
    was not the issue of the DEC Ring Purger issuing VOID frames (which are
    valid frames defined in the MAC spec) but that the Wellfleet router
    could not handling the VOID frames correctly (should ignore and not filter
    the frames as per the FDDI spec) if it tried to process them at a fast
    rate.
    
    Wellfleet is working on a fix which hopefully will be tested soon with
    our engineers.
    
    The moral of this story is:  If your customer is using Wellfleet
    routers and DEC's FDDI components, make sure the FDDI ring is greater
    then 2Km, or wait until Wellfleet fixes their problem.
    
    Lester  

>    The moral of this story is:  If your customer is using Wellfleet
>    routers and DEC's FDDI components, make sure the FDDI ring is greater
>    then 2Km, or wait until Wellfleet fixes their problem.
    
Doesn't this voilate the FDDI spec, a link shall be less than or equal to 
2Km?

Kenji

    No.  An individual link may only be 2km (multi-mode) but the ring
    length may be 200km.