Cannot start cluster on AIX/WebSphere6.1 2.9.0.GA

I've tried setting this system property:
java.net.preferIPv4Stack

I've also tried modifying Util.java:
    public static StackType getIpStackType() {
       return StackType.IPv4;
    }

I've tried supplying an IPv6 multicast address.

Here are my jgroups options(via ehcache):
UDP(
                    mcast_addr=239.0.0.20;
                    mcast_port=45566;
                    ip_ttl=1;
                                mcast_send_buf_size=150000;
                                mcast_recv_buf_size=80000),
                        PING(timeout=2000;num_initial_members=6),
                        MERGE2(min_interval=5000;max_interval=10000),
                        FD_SOCK,
                        VERIFY_SUSPECT(timeout=1500),
                        pbcast.NAKACK(gc_lag=10;retransmit_timeout=3000),
                        UNICAST(timeout=5000),
                        pbcast.STABLE(desired_avg_gossip=20000),
                        FRAG,
                        pbcast.GMS(join_timeout=5000;join_retry_timeout=2000;
                                shun=false;print_local_addr=true)

I always end up with an exception similar to this:
Caused by: java.lang.Exception: problem creating sockets (bind_addr=/10.117.248.196, mcast_addr=239.0.0.20:45566)
        at org.jgroups.protocols.UDP.start(UDP.java:224)
        at org.jgroups.stack.ProtocolStack.startStack(ProtocolStack.java:745)
        at org.jgroups.JChannel.startStack(JChannel.java:1760)
        ... 100 more
Caused by: java.net.SocketException: The socket name is not available on this system.
        at java.net.PlainDatagramSocketImpl.setOption(PlainDatagramSocketImpl.java:442)
        at java.net.MulticastSocket.setInterface(MulticastSocket.java:443)
        at org.jgroups.protocols.UDP.createSockets(UDP.java:385)
        at org.jgroups.protocols.UDP.start(UDP.java:220)
        ... 102 more