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VRRP (Virtual Router Redundancy Protocol) is an IETF standard for high availability networking. It is encumbered by Cisco patent, only available under RAND terms.

RAND licensing was deemed acceptable for IETF, but it was not acceptable for the free software operating system OpenBSD, so the OpenBSD team developed their own incompatible alternative, CARP (Common Address Redundancy Protocol). When OpenBSD requested official internet protocol number to IETF, IETF declined the request because CARP was not an IETF standard.

As a result, OpenBSD decided to use internet protocol number 112 for CARP, which is the same number used by VRRP. This clearly does not help the standard.

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