Our network engineer was able to solve this.  It had to do with how VLAN tagging is handled on physical vs. virtual environments.  Here is his explanation: "On the physical Unity boxes, we present a trunk port so that you can create interfaces in whatever VLAN you want. The catch is that you must specify which VLAN an interface is in. If you don't, then it defaults to VLAN 1. Since both physical Unity boxes are on the same switch, they can talk to each other over VLAN 1 but not to any other part of the network on VLAN 1. On the VSA, we cannot present a trunk port to the VM. The VLAN must be specified in VCenter. If the VM tries to specify a VLAN in the same way that the physical Unity does, VMWare throws the packet away as being invalid. So, on the physical Unity boxes, you MUST specify the VLAN. On the VSA, you MUST NOT specify the VLAN."
I have installed the UnityVSA Community Edition.  I'm trying to set up an Asynchronous File replication from my physical Unity 450F to the UnityVSA.  The connection fails in the 4th of 5 steps - "Refresh local system connections on remote system".  The error description says, "Although the remote system is registered, the connectivity validation has failed. Check for any network connectivity issues, and also ensure that the time skew between the systems is less than 10 minutes. Once fixed, run the verify operation on the remote system to resolve this issue. View alerts related to the remote system connections for more information. (Error Code:0x6500128)" The times are identical, and as far as I can tell, network communication is good. (I tried a connection between my 450F and a 550F and that worked fine.) The 450F has 2 SPs, of course, and therefore has 2 interfaces.  The VSA only has only one SP and one interface.  Is that my issue?
UnityVSA failed replication connection from physical Unity