Free stuff (UK) again

From: Paul Koning <pkoning_at_equallogic.com>
Date: Fri Jul 9 15:26:22 2004

>>>>> "Jochen" == Jochen Kunz <jkunz_at_unixag-kl.fh-kl.de> writes:

 Jochen> On Fri, 9 Jul 2004 14:00:57 -0400 Paul Koning
 Jochen> <pkoning_at_equallogic.com> wrote:

>> Sure, neat if you can find it.
 Jochen> There is plenty of FDDI stuff on ePay for cheap.

>> But FDDI is dead, dead, dead.
 Jochen> ??? Isn't all the stuff we use and talk about here "dead,
 Jochen> dead, dead"? Even 10 MBit/s Ethernet is "dead, dead,
 Jochen> dead". (At least in its 10Base5 and 10Base2 incarnations.)
 Jochen> FDDI is the "proper" and in most cases only available 100
 Jochen> MBit/s network technology for older machines like a SGI
 Jochen> Indigo or DEC 3000.

Sure, fair enough. I thought the discussion was about good fast
networks to use around the shop.

>> And Ethernet doesn't have any collisions either if you run it full
>> duplex.
 Jochen> And when two machines are pushing 8 MBit/s each to a third
 Jochen> machine? The target machine surely can't handle 16 MBit/s
 Jochen> with its 10 MBit/s physical link. So you loose bandwith due
 Jochen> to collisions in case of high load - the case where you don't
 Jochen> want to loose any bandwith.

No, that's congestion, not collisions. Collisions has a specific
meaning that applies ONLY to half duplex Ethernet. Congestion happens
in any network when there's more input than the bandwidth of the
output.

If you have more than 10 Mb/s worth of traffic, you need a link with
more than 10 Mb/s capacity -- FDDI is one, and so is 100BaseT. The
two are roughly the same in capacity, though the worst case latency of
FDDI is much higher than that of Ethernet. (Not that it matters in
practice.)

           paul
Received on Fri Jul 09 2004 - 15:26:22 BST

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