correct me if I am wrong, but link aggregation is used mostly for bandwith improvement and all aggregated ports have to be connected to the same LACP-aware switch ?
regarding the Oracle documentation (Oracle VM Server for SPARC 3.1 Administration Guide, Chapter 8 / Configuring and Using IPMP in the Service Domain), it should be possible to define and IPMP group...
Using VM server 3.1, I would like to configure a vswitch based on IPMP of 2 physical port so that IPMP is only configured on the primary domain and no more on guest domains.