A hack to allow multicast to work (to some extent) on FreeBSD -CURRENT:
add a route to 224.0.0.0/4 over our loopback interface. This seems
necessary to allow any multicast traffic to be transmitted out of the
machine / virtual nodes, and in particular allows RIP to work with
XORP. OTOH, for reasons beyond my willingless for further investigation,
quagga does not even properly open multicast sockets for RIP, regardless
whether using quagga built from the ports collection, or using a
package built for 6.2-RELEASE in compatibility mode :(