[rescue] u2 drive trays

Dave McGuire mcguire at neurotica.com
Tue Aug 19 00:45:10 CDT 2003

On Tuesday, August 19, 2003, at 01:32 AM, Curtis H. Wilbar Jr. wrote:
> Exactly how does 100Mbps FDDI compare to 100Mbps 100baseTX ?

   In general, it's faster and more reliable.  It's a more recent design 
than Ethernet, and it was better thought-out.

   Specifically, it has an MTU of about 4500 bytes...three times 
Ethernet's MTU, which makes for much more efficient transmission of 
large packets.

   It also does media arbitration in a sane way...via token passing, not 
by Ethernet's INCREDIBLY dumb "there was noise on the line, I guess 
there was a collision, I'll wait a while and try again!" approach.  
This means you can push an *unswitched* FDDI ring to 95Mbps or more 
without degraded performance.  Try THAT with ethernet.

   To get any reasonable performance out of ethernet, you have to modify 
one of the basic points of its design...by making it fully switched.  
Otherwise, good luck getting more than 50-55Mbps out of it with more 
than a few active nodes.  I like to get 100Mbps out of my 100Mbps 
networking technology, thank you. ;)

   It's also much "smarter" than ethernet...A FDDI ring "knows" which 
nodes are inserted, and there's a graceful node insertion/removal 

> I've never used FDDI... but enough of the discussions on here have
> me interested....

   That's good to hear.  FDDI is the way networking is *supposed* to be 
done...as compared to the cheap-ass, poorly-designed kludge that is 

> Is it pretty cheap to get some FDDI gear these days ?

   Yes.  eBay is your friend.  People who think FDDI is older than 
ethernet (which it isn't) and then assume that that means it's somehow 
"bad" frequently dump high-end FDDI stuff on eBay all the time.  I've 
picked up *current model* SysKonnect many-hundred-dollar-pricetag 64bit 
66MHz PCI FDDI interfaces (for big Suns) on eBay for $15.

> I have PCs, sbus Suns, PCI suns, and a mix of other machines (Mac
> (NuBus, and soon a PCI Mac, and possibly an iMac, VAXstation 2000,
> DECstation 5000, a couple of PCI based Alphas (one DEC, one of the
> old NoName based systems, and two Aspen Alpine 275XS), etc.

   You should be able to get FDDI on all of those except for the iMac, 
and very cheaply.  There's no FDDI support in MacOS X yet, though.

> My file server is currently a Solaris 8 Intel box.

   Dunno about that...I've never run Solaris/x86 but SysKonnect probably 
has drivers for it.

> What is the best way (and alternately what is the cheapest way) to
> link FDDI and 100baseTX efficiently ?

   The best way is to blow a few bucks and pick up a Cisco Catalyst 5000 
on eBay.  Those are *really nice* switches, faster than all hell, and 
built like tanks.  They do all the fancy vlan stuff you'd ever want to 
do.  You can pick one up with 10/100Mbit ethernet interfaces and a FDDI 
interface for about $300.  That's about the only thing that'd be 
expensive about getting into FDDI and "doing it right".

   Email me privately for more info if you're interested...I typed up a 
long introduction for a friend a few days ago, detailing makes & models 
of cards and what's-supported-by-what information...perhaps I can dig 
it out of my sent-mail for you.


Dave McGuire                 "You don't have Vaseline in Canada?"
St. Petersburg, FL                     -Bill Bradford

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