[HECnet] FDDI and DECNET, clustering

"Sampsa" == Sampsa Laine <sampsa at mac.com> writes: Sampsa> Guys, I've just received a DEFPA-DB PCI-FDDI adapter from Sampsa> ebay, my plan is to install it in CHIMPY and then connect Sampsa> CHIMPY to CHIMP via this for clustering. Sampsa> Anybody know how I would go about cabling such a beast, there Sampsa> are four fibre optic ports on these things? Wow, that takes me back a bunch of years... There are two basic FDDI cabling approches: dual ring, and tree of concentrators. The DEFPA can be hooked up either way because it has the two ports (type A and B ports). 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. It has single-fault tolerance, but it doesn't support hierarchical wiring (wiring closets). The single-fault tolerance means you can make a chain instead of closing the ring, that's equivalent to the ring with a single cable busted. If you have a concentrator (a box with either A/B ports or S port, plus a number of M ports) plug either A or B into an M port and leave the other unused. Finally, if you have another device with an S port (a "single attached station") you can plug that into either the A or the B port, leaving the other port available for another S port, or another A/B port. I don't think you should have S to A and B to M, but I don't remember for sure. If you have concentrators, the rule is that any single attached devices plug into M ports, while dual attached devices plug either into an M port or into the root dual ring. paul