[HECnet] FDDI and DECNET, clustering

[Paul Koning]

"Sampsa" == Sampsa Laine <sampsa at mac.com> writes:

If you have other FDDI devices that also have A or B ports, just
plug A to B in a circular fashion, and you have a dual ring.   This
is the topology that FDDI originally started with early in its
development.

Sampsa> So if I have two dual port PCI cards, one in machine 1, one
Sampsa> in machine 2, I wire them:

Sampsa> 1.A.   -> 2.B 2.A -> 1.B

Sampsa> To create a circle? Do I HAVE to do this, i.e. can I just
Sampsa> wire one cable between machine 1 and 2 (the cables are
Sampsa> EXPENSIVE, like 3x what the adapter cost me)?

One connection is fine.

As I mentioned, the standard topology for A/B stations (Dual Attached
stations) is A to B in a circular fashion.   That creates a pair of
rings.   And that topology can handle single faults: the loss of a
single port or single cable.

If you just connect the two stations with a single cable, what you
created is a dual ring with a single fault -- one of the two cables is
missing.   That will work just fine.

	  paul