It is a question about "Multi-site constitution of three sites"

It is a question about “Multi-site constitution of three sites”

SwitchesName:Switches_A DN:2000(RoutingPoint),2001(RoutingPoint) SwitchesName:Switches_B DN:2000(RoutingPoint),2001(RoutingPoint) SwitchesName:Switches_C DN:2000(RoutingPoint),2001(RoutingPoint)

I show “A flow of call” as follows.

[Usually]
When I received a telegram in “site1(Switches_A)”

→ 2000(Switches_A) → 2001(Switches_B)

[An obstacle of “site2(Switches_B)”]
When I received a telegram in “site1(Switches_A)”

→ 2000(Switches_A) → 2001(Switches_C)

As above usually “Switch_A → SwitchesB”.
I become “Switch_A ⇒ SwitchesC” only in the case of “An obstacle of “site2(Switches_B)””.

On a strategy, you must acquire a switch name of a forwarding address.
In a strategy, it is usually acquired SwitchesName of “Switches_B”.
In a strategy, I acquire “SwitchesName of Switches_C” at the time of an obstacle of Switches_B.
Do you know a method?
Thanking you in advance.

Is there a method to confirm that "Switches_B
" does not fall?