| There is a manual which used to be shipped with a DEChub 90
called "DEChub 90 Ethernet Backplane Owners Manual EK-DECHUB-OM-001
In chapter 2 under the heading Configuration Rules, there are
a number of configuration rules on how to connect the the DEChub90
with regard to number of repeaters, segment length, and location of
bridges.
In terms of segment length, they appear to have maybe violated
configuration rules for the DEChub90.
Some basic rules referenced in above manual.
ThinWire segment: maximum length of 185 meters
maximum of 30 stations
ThickWire segment: maximum length of 500 meters
maximum of 200 stations or nodes.
Repeaters: There can be no more than two repeaters between any two
stations on a network segment.
Bridges: Maximum of seven bridges between any two stations on a LAN.
Other critical rules to remember....
The DEChub90 backplane must always be at one end of the ThinWire
segment.
For cable length planning, the DEChub90 backplane is the equivalent of
65 meters of ThinWire cable. so when the DEChub90 is installed at one
end of a ThinWire segment, the segment is limited to a max length
of 120 meters.
The DEChub90 backplane, with or without work group units installed,
is to be considered equivalent to 15 nodes on a ThinWire segment.
These are the primary rules to be applied when using DEChub90's.
So they may have violated rules depending on the length of those
pieces of ThinWire cables connected to the ThickWire segment.
Also, they may not have physically placed the DEChub90 at one
end of the ThinWire segment, even though your description appears
to suggest that they have. Check this to be sure.
That's the jist of the rules needed to be adhered to.
Bob
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