You do have more then one t5-2 machine ?

If you have only one root complex on each (only primary domain) and take care you don't over commit resources (cpu / mem), you should be able to live migrate a ldom from one machine to another.
All you have to watch is that the names are the same for all the virtual devices and the backend devices are the same (naturally)
I am not sure if you can have 2 root complexes (primary / secondary) and do a live migrate of guest ldom inside the same machine.

That is not a use case at all, but i could be wrong (i have never made such setup).

Use case for root complexes is two have complete hardware separation of, for instance, production and test and it is used on machines with more sockets, more cards etc.

Take this example - sneezy is a production ldom and sloppy is a test ldom.
We are using only primary domain only one root complex logically separated production and test

Both t5-2 have same names and configuration

FC (2 FC 2 PORT cards)

1 port from each FC card is for production usage (zoned on switch, production host group on storage)
1 port from each FC card is for test usage (zoned on switch, test host group on storage)

This way if one FC cards dies, production and test will continue to operate.

You just prefix when create a VDS (virtual disk services) with prod or test depending.

So you have sneezy-prodvds and sloppy-testvds on both sparcs in primary domains, with disks added to them according to layout above (test and prod host groups and paths).

Remember you have freedom here to add both to any ldom (test or production disk), only naming policy is telling you to which VDS you will add each disk.

NETWORK (2 LAN 4 PORT cards, 8 ports total, dladm show-phys)

Now you make a choice, will you use aggregation, ipmp or dlmp

Example here is with aggregation (aggr0,aggr1).

You take 2 ports from one card and 2 ports from other card which lead to the same LAN switch and create an aggr0 interface,then create a production-vsw from that interface (with production vlan tags configured pvid/vid)
You add vnet to sneezy ldom from production-vsw (or any other production ldom)

From other network ports (2 from each card remains), you create an aggr1 interface, then create a test-vsw from that interface (with test vlan tags configured on vsw pvid/vid)
You add vnet to sloppy ldom from test-vsw (or any other test ldom).

This way if one card dies, you will loose 2 production and 2 test paths, but both test and production will continue to operate on lower bandwidth (2 x instead of 4 x)

VSW and VDS are named the same on both sparc machines primary domain (this is a requirement for migration (live or cold).

Now you have sneezy production ldom, with production-vsw --> vnet for networking and disk added via proper FC path and added to sneezy-prodvds and sneezy ldom.

Also you have sloppy test ldom, with test-vsw --> vnet for networking and disk added via proper FC path and added to sloppy-testvds and sloppy ldom.

PRIMARY DOMAIN network with tagging on both sparcs :

I recommend using a separate vlan for primary domain IP addressing (control domain can be isolated on vlan layer on network for security reasons)

Since you have tagging on switch and aggr0/1 interfaces, you will have to create a tagged interface for primary domain.
dladm create-vlan -l aggr1 -v <your vlanid> vlan-link
If you don't provide the vlan-link it will create a aggr1<yourvlanid> interface.

This is the interface you will use to create ip address for primary domain on both machines. We are using aggr1 here (test network) for live migration of all ldoms (both production and test), but you are free to choose any (0 or 1) depending on the network topology and bandwidth required.

Now you can issue a test live migration from host1 to host2 with command
ldm migrate -n sloppy host2 # -n switch is just to check if migration will work and it is a great way to check if configuration on both physical machines are the same.

Final result that you can migrate any production or test guest LDOM to any sparc t5-2 machine without of interrupting the service (live migrate) or cold migrate (with ldom down), while having LAN and FC resources seperated for production and test and having more or less "keep it simple" configuration

Be sure firmware levels are the same on all your sparc t5-2 machines for live migrate to work (cold migrate will not have this limit).

Hope that helps.

Regards
Peasant.