We have requirement where we have to manually switch between active and DR vpn. so few questions
1. How to connect to multiple vpns?
2. 2. how to identify the vpn is down ?
The answer depends a little bit on which protocol/API you want to use.
The easiest answer: Use Solace Enterprise APIs (= SMF as protocol) - all these client APIs have the concept of a hostlist implemented.
The application will try to connect to all hosts in that hostlist one after the other until there is a successful connection.
And because you can't connect to a shutdowned VPN (that's the answer to the question "How to identify the VPN is down ?". Answer: If you can connect, the VPN is NOT shutdowned), that does work automatically.
Often, such setups have a hostlist with 4 members: 2 hosts for the members of an HA cluster, and 2 hosts for the members of the DR-HA cluster.
Does that answer your questions ?