Description:

Failover and monitoring daemon for LVS clusters
keepalived is used for monitoring real servers within a Linux
Virtual Server (LVS) cluster. keepalived can be configured to
remove real servers from the cluster pool if it stops responding,
as well as send a notification email to make the admin aware of
the service failure.

In addition, keepalived implements an independent Virtual Router
Redundancy Protocol (VRRPv2; see rfc2338 for additional info)
framework for director failover.

You need a kernel >= 2.4.28 or >= 2.6.11 for keepalived.