carp: document the new VRRPv3 support

Sponsored by:	Rubicon Communications, LLC ("Netgate")
Differential Revision:	https://reviews.freebsd.org/D44776

sbin/ifconfig/ifconfig.8

@@ -25,7 +25,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd November 08, 2023
+.Dd May 1, 2024
 .Dt IFCONFIG 8
 .Os
 .Sh NAME
@@ -3151,6 +3151,20 @@ announcements to.
 Restore the default destination address for (IPv4)
 .Xr carp 4
 announcements, which is ff02::12.
+.It Cm carpver
+Set the protocol version.
+Valid choices are 2 (for
+.Xr carp 4)
+and 3 (for VRRPv3).
+This can only be set when
+.Xr carp 4
+is initiated.
+.It Cm vrrpprio
+Set the VRRPv3 priority.
+Valid values are 1-255.
+.It Cm vrrpinterval
+Set the VRRPv3 Master Advertisement Interval.
+Values are in centiseconds.
 .El
 .Sh ENVIRONMENT
 The following environment variables affect the execution of

share/man/man4/carp.4

@@ -24,7 +24,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd March 6, 2023
+.Dd April 12, 2024
 .Dt CARP 4
 .Os
 .Sh NAME
@@ -93,6 +93,17 @@ or through the
 .Dv SIOCSPEER
 .Xr ioctl 2 .
 .Pp
+.Xr carp 4
+can be configured to use either the non-standard CARP protocol, or VRRPv3 (RFC 5798).
+Use the
+.Cm carpver
+parameter to select either 2 (CARP) or 3 (VRRPv3).
+VRRPv3 specific parameters can be configured using the
+.Cm vrrpprio
+and
+.Cm vrrpinterval
+parameters.
+.Pp
 CARP virtual hosts can be configured on multicast-capable interfaces: Ethernet,
 layer 2 VLAN, FDDI and Token Ring.
 An arbitrary number of virtual host IDs can be configured on an interface.