[rescue] Re: CDDI/FDDI from Cisco (old stuff--any good?)

[Dave McGuire]

On August 18, Robert Novak wrote:
> I asked a guru friend locally, and he said FDDI's better than FE if you're
> running half duplex FE, but you're stupid if you're running fast ethernet
> half duplex. 

  Breakdown and simplification:
    1) you're stupid if you're running fast ethernet half duplex
    2) full duplex assumes a guarantee of no collisions
    3) the only way to guarantee no collisions in ethernet is to
       switch every node
    4) running a fully switched ethernet network is modifying
       (defeating?) one of the basic design principles of ethernet

  Therefore:
    In order for one to run fast ethernet and not be stupid, one must
    modify one of the basic design principles of fast ethernet.

  Just something to think about.

> I suspect switched fast ethernet will be functionally equivalent to FDDI,
> maybe better if the FDDI is just concentrator'ed. But it's not as cool to

  *bzzzt*

  You're forgetting switch overhead (which admittedly is shrinking as
embedded CPUs get faster, so let's just forget about that), total lack
of any sort of redundancy features, and an MTU that's three times that
of ethernet's.  Real-world, these things translate to networks that run
faster and break less often.

> say you're running fast ethernet at home. And how many of us DON'T do a
> lot of what we do because of the coolness factor? :-)

  For some of us, it actually involves paying for food and rent.
Looking at your .sig, Rob, I know you know where I'm coming from. :-)

      -Dave

-- 
Dave McGuire
Laurel, MD