[j-nsp] j-series and clusterip / multicast mac addresses

[seph]

I'm playing with linux's ClusterIP behind a couple of j2320 routers. It
works by having several machines share an ip address using a multicast
mac address. However, my j2320's don't seem to like it.

tcpdump shows they as sending an arp request, and ignoring the arp
response. If I statically assign an arp entry, things do work, but I need
to dynamically learn them. I don't think I have multicast enabled, but
when I tried enabling it I saw the same behavior.

Currently running junos 9.0r2. 

Anyone have advice on how to do this?

seph