George White wrote in a message to Mike Bilow:
MB>Yes, you can have multiple hubs.  Signal loss is the limiting 
MB>factor.  The only advantage to using hubs in ARCnet is that it 
MB>makes it easier to run the wires.  If the physical arrangement 
MB>of your nodes allows it, a bus is fine.
 GW> But the specs I have all say that the signal loss through 
 GW> passive hubs means that two cannot be connected directly 
 GW> together. The Datapoint Cabling Guide goes as far as suggesting 
 GW> that passive hubs are not installed in wiring cabinets to 
 GW> minimise the risk of this happening. They specify that an 
 GW> active hub is required between two passive hubs. 
In reality, the loss through passive hubs is less than through a long cable 
run.  You can trade off cable length for a passive hub, and this will work 
reliably.  The issue is how much effort you want to put into an ARCnet LAN.
 GW> The Arcnet Standard makes interesting reading on the timings 
 GW> and state machines required. I wonder if it ever got approved? 
 GW> (the copy I have is an unapproved draft of version 1.4)
I think so.  ARCnet was a proprietary system from Datapoint, and it did not 
last long enough to warrant formal international standardization.  The 
Datapoint documentation is authoritative.
 
-- Mike
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