What is CARP and how does it work?
CARP is a tool to help achieve system redundancy, by having multiple computers creating a single, virtual network interface between them, so that if any machine fails, another can respond instead, and/or allowing a degree of load sharing between systems. CARP is an improvement over the Virtual Router Redundancy Protocol (VRRP) standard. It was developed after VRRP was deemed to be not free enough because of a possibly-overlapping Cisco patent. For more information on CARP’s origins and the legal issues surrounding VRRP, please visit this page. To avoid legal conflicts, Ryan McBride (with help from Michael Shalayeff, Marco Pfatschbacher and Markus Friedl) designed CARP to be fundamentally different. The inclusion of cryptography is the most prominent change, but still only one of many. How it works: CARP is a multicast protocol. It groups several physical computers together under one or more virtual addresses. Of these, one system is the master and responds to all packets destined for t
