vMotion across Clusters

Hello,

We are designing a datacentre and the networking team have suggested creating a VLAN and network subnet for each vMotion network per VMware Cluster.

I guess this will mean we cannot vMotion VMs between Clusters?

What a better idea be to create one network/VLAN to be used between all clusters?

What about security of data on these vMotion network(s).

ANy thoughts would be greatly appreciated!

Thanks,

Peter.