Hi Mike,
You wrote to Greg MacLellan:
MB> GM> just a couple questions about ArcNet..
MB>Keep in mind that the answers for ARCnet are very different than for 
Etherne
Too true!

MB> GM> Also, is it possible to use two passive hubs, or do i need
MB> GM> to get an active hub? (in which case i'll switch to a
MB> GM> bus-topology as its cheaper just to buy t's than it is to
MB> GM> buy an active hub).
MB>Yes, you can have multiple hubs.  Signal loss is the
MB>limiting factor.  The only advantage to using hubs in
MB>ARCnet is that it makes it easier to run the wires.  If the
MB>physical arrangement of your nodes allows it, a bus is fine.
But the specs I have all say that the signal loss through passive hubs
means that two cannot be connected directly together. The Datapoint
Cabling Guide goes as far as suggesting that passive hubs are not
installed in wiring cabinets to minimise the risk of this happening.
They specify that an active hub is required between two passive hubs.
MB> GM> is that possible to do? will two work together like that?
MB> GM> will it degrade preformance?
MB>The physical topology has no effect on ARCnet performance,
MB>because ARCnet uses a token bus time slot allocation scheme.
The Arcnet Standard makes interesting reading on the timings and state
machines required. I wonder if it ever got approved? (the copy I have is
an unapproved draft of version 1.4)
George
 * SLMR 2.1a * KEYBOARD - Used to enter errors int a computer.
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