links on the blink (fwd)
Paul A Vixie
paul at vix.com
Mon Nov 6 08:21:09 UTC 1995
> > hence this fddi is at 90%: why not add another onte? It is bridged anyways.
> > Mike
> Maybe because they want people to pay the difference to upgrade...
Maybe because inside a DEC GIGAswitch, there's an 800Mb/s crossbar switch
such that while the peak b/w between any pair of ports is limited by FDDI's
spec (100Mb/s, or 200Mb/s full duplex), the peak b/w between all pairs of
ports is limited to a much higher number (800Mb/s.) Thus Andrew's comment
earlier about the MAE-East GIGAswitch humming along nicely at 190Mb/s peak
load. The shared FDDI can't do that, and a bridge between two shared
FDDI's couldn't do that.
DEC did something wonderful with that GIGAswitch, it would behoove you both
to understand what it was in case you need similar technology inside your
own hubs. Not to mention the importance of choosing the right way to connect
at a MAE or NAP, and especially not to mention the importance of knowing
which side of the MAE-W T3 you want to be on.
(As long as I'm singing the GIGAswitch's praises, I'd like to add that DEC
is planning a GIGAswitch-to-GIGAswitch interconnect product but it will only
run at a few hundred megabits, not the full b/w of the crossbar; and further,
they now sell an ATM version of the GIGAswitch in case you don't want FDDI
but you need an ATM with working congestion control.)
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