The main goal of the keepalived project is to add a strong & robust
keepalive facility to the Linux Virtual Server project. This project
is written in C with multilayer TCP/IP stack checks.

Keepalived implements a framework based on three family checks: Layer3,
Layer4 & Layer5. This framework gives the daemon the ability of checking
a LVS server pool states. When one of the server of the LVS server pool
is down, keepalived informs the linux kernel via a setsockopt call to
remove this server entrie from the LVS topology.

In addition keepalived implements a VRRPv2 stack to handle director
failover. So in short keepalived is a userspace daemon for LVS cluster
nodes healthchecks and LVS directors failover.