We have a QNX4 dual network with 50 nodes in a plant.
We discovered an interesting behavior of the network,
when one of the two networks - say logical 1 - is down.
The network manager tries to transfer through the bad
network in every 40 seconds (this is the default value
of Net -t option). It couses a 3 second delay in
data transfer (the default value of Net.* -t and -n
options is 20 - 1 second - and 3).
You can say, that this is a documented behavior of the
network manager. The big surprise is, that the network
manager tests the bad network with the real message instead
of a test message. If I were the software designer of Net,
I should use a test message for testing the link whitout
disturbing the high level communication.
Of course I have the possibility to decrease the -t and -n
options of Net.* driver, but in some circumtancies it can
couse other problems.
So my quiestions are: Is it true, that the feature of a dual
network is worse than a single network, when one of the
networks is down? Has anybody faced this problem before?
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