I rad some article. Keepalived over GRE tunnel for failover on VPS environment http://blog.killtheradio.net/how-tos/keepalived-haproxy-and-failover-on-the-cloud-or-any-vps-without-multicast/ but, I don't know how to configuration? and How to call this architecture? only I Know that How to config Master/Backup configuration at keepalived. What I want to know that How does work keepalived? I want to design this.... XMPP Server(EC2) | ------------------------------------------------- keepalived Master(EC2) - keepalived Backup(EC2) HAProxy #1 HAProxy#2 ------------------------------------------------- | Casandra#1 Casandra#2 Casandra#3 Casandra#4 Thanks! but What I want to know how to work on keepalived with unicast patche modul. ELB is expansive. and this is first totaly design. [Flow] ELB -- XMPP Server -- ELB -- Casandra ELB | XMPP#1 XMPP#2 XMPP#3 XMPP#4 | ELB | Casandra#1 Casandra#2 Casandra#3 Casandra#4 and change first design. [Flow] ELB -- XMPP Server -- HAProxy Master(Casandra Farm) -- Casandra ELB | XMPP#1 XMPP#2 XMPP#3 XMPP#4 | ------------------------------------------------- keepalived Master(EC2) - keepalived Backup(EC2) HAProxy#1 HAProxy#2 ------------------------------------------------- | Casandra#1 Casandra#2 Casandra#3 Casandra#4 this is second. [Flow] ELB -- HAProxy(XMPP Farm) -- XMPP Server -- HAProxy(Casandra Farm) -- Casanda It's OK? ELB | HAProxy#1 HAProxy#2 HAProxy#3 HAProxy#4 XMPP#1 XMPP#2 XMPP#3 XMPP#4 | Casandra#1 Casandra#2 Casandra#3 Casandra#4