One of our Clients designed the system with double redundancy. Short overview of such type of system
Pros:
- No single point of failure
- Client’s PBX has additional layer of redundancy with 3rd Asterisk in a case if main cluster under Virtual IP gets down
Cons:
- Not usable with end-devices like softphones/phones which can only register to one server (can only be used with main cluster)
Notes:
- 3rd Asterisk server should not be used when main cluster is operational (it should have lower priority in the routing table)