You should be able to create an I/O service domain depending on the T series HW where the service I/O has assigned one of the network interface sets and the primary has the other. Then you create a VSW for the primary and the secondary for those networks with the appropriate VLAN information. Then for the ldom guest your assigning one NIC for the same network from the primary and secondary domains. This should allow network connectivity if primary or secondary instances has troubles. This works as well with HBA's if your using fiber channel for Storage.
The OVM for Sparc documentation talks about these I/O, root and SRIOV types of domains and the Ops Center documentation covers configuring via Ops Center.
The other concept unique to Ops Center is the server pool where multiple cdom hosts all configured the same regarding the Storage Libraries and networks associated to them are made into a Server Pool a logical construct in Ops Center. If any single cdom host becomes unavailable the OC environment can recognize and try and auto-migrate a guest from the original host to an alternate cdom host if enough cpu and memory resources are available.
Main Ops Center 12.4.0 (current release) documentation URL
Enterprise Manager Ops Center Virtualization Reference
5 Oracle VM Server for SPARC
6 Server Pools
I hope this helps
That's a really good answer.