High Quality Content by WIKIPEDIA articles! The Common Address Redundancy Protocol or CARP is a protocol which allows multiple hosts on the same local network to share a set of IP addresses. Its primary purpose is to provide failover redundancy, especially when used with firewalls and routers. In some configurations CARP can also provide load balancing functionality. It is a free, non patent-encumbered alternative to Cisco`s HSRP. CARP is mostly implemented in BSD operating systems.