IP multipathing is a configuration that allows an IP address to automatically failover between two or more physical network interfaces. Prior versions of Solaris did already have IPMP support, but it was a bit hacky. It involved using ifconfig to assign two or more interfaces to a group, and then basically hoping the kernel did a good job from there. It was then up to the kernel to plumb and unplumb a secondary IP address (such as bge0:1) from one physical interface or another.

IPMP support in Solaris 11 is much more refined. The floating IP is given its own persistent, virtual object, at the same level as any other IP object at the ipadm layer. This then allows you to apply persistent tuning options to it.

There is also a new tool specifically written to monitor IPMP; predictably, it is called ipmpstat.