Communication Redundancy - Moxa Technologies EtherDevice User Manual

Featured Functions

Communication Redundancy

The Communication Redundancy function allows the user to set up redundant loops in the
network to provide a backup data transmission route in the event that a cable is
inadvertently disconnected or damaged. This is a particularly important feature for
industrial applications, since it could take several minutes to locate the disconnected or
severed cable. For example, if MOXA EtherDevice Server is used as a key communications
component of a production line, several minutes of downtime could cause a big loss in
production and revenue.
The Communication Redundancy function uses Spanning Tree protocol to identify one
switch as the "root" of the network, and then automatically blocks packets from traveling
through any of the network's redundant loops. In the event that one branch of this tree
becomes disconnected from the rest of the network, the Spanning Tree protocol
automatically readjusts the tree (if possible) so that the part of the network that was
disconnected can reestablish contact with the rest of the network.
Perhaps the main advantage to using Spanning Tree protocol (IEEE802.1D) to manage
redundant loops is that it is an open protocol, and consequently is compatible with products
from other manufacturers (Cisco, for example) that use Spanning Tree protocol.
Initial Setup
MOXA EtherDevice Server User's Manual 6-23