I have been heads down on an Exadata Poc , and only now, got a chance to browse through the new features in 11.2.0.2. The out of place upgrade feature looks interesting.

This new feature in grid infrastructure installation had me really overjoyed (Anyone who has had the pleasure of configuring IPMP, Auto Port Aggregation, Etherchannel etc (based on the o/s) and setting it up correctly to work with Rac, will understand my Joy) . Starting with 11.2.0.2 you do not have to bond the interfaces (If you have redundant GigE nics you are going to use for your private interconnect) you are going to use as the private interconnect. If you have two different interface names to be used for the private interconnect you can provide both the interface names to the oracle grid infrastructure installer and oracle clusterware will create a Highly Available IP Address (HAIP).

Oracle Clusterware, Rac and ASM uses these  load balanced highly available interfaces for communication.

Details can be read at http://download.oracle.com/docs/cd/E11882_01/install.112/e17212/prelinux.htm#BABJHGBE for Linux.

HAIP info can also be found in the 11R2 Clusterware white paper.

Julian Dyke has a blog post that says that MULTICAST has to be enabled for the Network interfaces to enable this to work.

Enabling multicast on the interconnect network is a requirement with 11.2.0.2 Rac.My Oracle Support Notes 1228471.1,1212703.1 details how Multicast can be enabled and checked.