Direct connect between 5200 and 5220 -- possible??

So, we have a 5200 appliance and windows master in one domain, and a 5220 acting as its own master in another.

Using Storage Lifecycle Policies, we are replicating between the 5200 and 5220.  Seems to be working OK, but the data is travelling on our regular IP network.  And we'd like to move the 5220 to another building for added protection.

We were told you cannot directly connect the 5200 and 5220, say, through fibre or some such, so, how are other folks handling this?

Any hints or info would be appreciated!!