High Availability Theoretical Basics - Schneider Electric

High Availability with Collaborative Control System
The following diagram illustrates these four occurrences:
1
2
To protect the network architecture from these events, several communication
protocols are proposed and described in the following section.
A solution able to enhance networking availability while preserving budget
considerations consists of reducing both limitations of an Ethernet network:
distributed as a bus, but built as a ring. At least one specific active component is
necessary: this is a network switch usually named Redundancy Manager (RM).
Consider an Ethernet loop designed with such a RM switch. In normal conditions, this
RM switch will open the loop: which prevents Ethernet frames from circulating
endlessly in a loop.
3
4
If a break occurs, the
Redundancy Manager
switch reacts immediately,
and closes the Ethernet
loop, bringing the network
back to full operating
condition.
Note that the term Self
Healing Ring concerns the
ring management only;
once cut, the cable is not
able to repair itself.
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