[rescue] FDDI questions

George Adkins george at webbastard.org
Mon Feb 18 20:01:05 CST 2002


> 1) If the MIC connector is also known as the FDDI connector, then why do
> most FDDI cards have SC connectors instead? 

Newer equipment.  Lots of EISA and older S-Bus cards have MIC connectors,  
the newer PCI and S-Bus cards have SC connectors because the format takes up 
less space and you can get a DAS in one slot.

> And why are MIC-SC cables
> so rare? It's easy to find MIC-MIC and MIC-ST, but only perhaps one place
> in four that carries those also has MIC-SC. I've been scoring 1 to 8 meter 
MIC/SC for around $5-$10 each shipped.

>
> 2) Grumping aside, I'm looking forward to setting up an FDDI/CDDI ring.
> I have a Cisco WS-C1100 workgroup stack with eight FDDI SAS MIC, eight
> CDDI, and even a single DAS MIC option installed. Question: since FDDI is a
> loop which passes into and out of each device it's attached to, it seems
> like it should be possible to link two concentrators simply by connecting
> an arbitrary port on one to an arbitrary port on the other -- the loop
> should simply flow through both without any special effort, right? 

Right.  Dual attach provided a redundant double ring, Single attach just 
loops a single path through the station

>    (Actually, that raises a third question: why the heck did MDI/MDIX come
> about, anyway? Wouldn't it make a lot more sense to simply have one pinout
> and all cables be crossover, so that anything could be connected to
> anything else with any cable one happened to have sitting around? Or was it
> intended to be a safety measure to keep idiots from connecting a hub to
> itself?)
>
IMHO, I would guess it's a hold-over from the telco-style wiring system.

George



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