an open source daemon that implements the VRRP standard.
The keepalived project is an open source implementation of the VRRP protocol as well as a configuration interface to the Linux ipvs framework. VRRP is based on Cisco's proprietary Hot Standby Router Protocol (HSRP) concepts. When these two portions of the application are used in concert, a pair of linux servers can be a stable, low-cost alternative to commercial load balancers.
Cisco has claimed that VRRP is protected under HSRP patents, so using keepalived is legally questionable.