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Determining Your ControlNet Media Requirements
D-19
Figure D.11
SEGMENT 1
trunk cable A =
terminators
terminators
trunk cable B =
repeater B
Node
Node
repeater A
Node
Node
trunk cable B =
trunk cable A =
terminators
terminators
SEGMENT 2
43630
To use redundant media, all nodes must support redundant media.
IMPORTANT
Make sure you do not mix A and B cable
connections in a redundant operations. A node
supporting redundant trunk-cable connections will
function even if trunk cable A is connected to the B
connector on the node and vice-versa. However, this
makes cable fault indications (on the hardware or in
software) difficult to interpret and makes locating a
bad cable segment extremely difficult.
When in redundant cable mode, each node
independently decides whether to use channel A or
channel B. This decision is based on error counters
internal to each node. Redundant cabling is only
valid if there is only one fault on the network. In
other words, if you have a proper redundant cabling
system and you remove node 3 on trunk A and node
4 on trunk B the system will not operate correctly
because a double failure has occurred.
Publication CNET-UM001A-EN-P - March 2004