On Linux platforms under IPv4 addresses, JGroups binds to the multicast address to avoid the promiscuous traffic problem.
This arrangement no longer works with IPv6 addreses and a Java SocketException is generated and a WARN message written to the AS logs.
However, JGroups recovers from this exception and and then joins all the necessary multicast groups it needs without directly binding to the socket (i.e. it joins multicast groups in the standard way).

This, the only negative impact is the generation of an error emssage which might confuse the user. The error message which is generated when we try to bind to IPv6 multicast address is:

16:35:19,970 INFO [DefaultPartition] Initializing partition DefaultPartition
16:35:20,231 WARN [UDP] could not bind to /ff02:0:0:0:0:1:2:3 (IPv6 address); make sure your mcast_addr is of the same type as the IP stack (IPv4 or IPv6).
Will ignore mcast_addr, but this may lead to cross talking (see http://www.jboss.com/wiki/Edit.jsp?page=CrossTalking for details).
Exception was: java.net.SocketException: Invalid argument
16:35:20,289 INFO [STDOUT]
---------------------------------------------------------
GMS: address is fe80:0:0:0:215:17ff:fe2d:6821:44270 (cluster=DefaultPartition)
---------------------------------------------------------

This error message should longer appear once the related issue in JGroups is fixed.