I came up with idea to set up stand with two kamailio and one b2bua server (for routing).

The idea consists of failover for dialogs, transactions.

So if one of kamailio nodes is down, another one is able to catch up the dialog and let users to properly end up the session.

For better realizing of it, I will try to describe the idea step by step:

1. UAC invites UAS, they've done three-way-handshake, media stream is up.

2. Kamailio that processed this dialog is down.

3. Users decided to end the session with BYE method, but proxy that processed their three-way-handshake recently is down, so one of ua sends BYE to the destination route that contains domain name (that both kamailio serve), BYE achieves the second kamailio to let him properly end the dialog.

 But, there is a big but, this second kamailio hasn't ever known about this dialog, he doesn't support any transactions for it and furthermore he doesn't know anything about this call-id.

So the solution for it, as I think, is hidden in db mode for user location (columns that contain call-ids, branches etc.

But I need to be sure, if I'm on the right way.

For purpose, where one ip is served by two nodes, I have two solutions:

-First one. I want to create heartbeat cluster with two kamailio nodes, they will have one shared ip address, so when one node gets down, another one brings up shared ip interface and implements the same actions that master does.

-Another method is to assign a few ip addresses to one domain name (ip addresses of different kamailio proxies).

So the goal looks simple, if someone has ever done something like that, I will be glad to read the ideas.

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