Ideally yes. By default you'd see that the vproxy you have configured would have been set to use hotadd (13 sessions) and have NBD set to 0. So it will only be able to backup vm's that it has direct access to, so to its datastore(s) that the vm vmdk's are located on. We always deal with esxi clusters in which all nodes have access to the same datastores, so that one vproxy would be able to do the backups. However other esxi clusters would have access to other datastores and hence would require at least one vproxy to be located on that esxi cluster. We now changed our design so that we'd have even two vproxies on each multinode esxi cluster, to have a failover in case one vproxy is not working and also to be able to perform maintenance (for example an upgrade (or rather it is a redeploy using a newer ova nowadays completely integrated from nw19.3 or so onwards)) on a vproxy without affecting backup/restore. So you might wanna deploy more vproxies, one within each esxi cluster, to prevent too much backup data flowing between esxi nodes in one cluster to the vproxy on another when you'd use NBD. Would require 10Gb connections also according to Dell recommenations. But even regardless we don't use NBD and only use hotadd. I would have expected backups to fail in case it wouldn't be able to access the remotely located vm's as NBD would be set to 0? Possibly that vproxies might not even be required in the future as for example Dell PPDM already supports vproxyless vm backups by hooking directly a plugin into esxi hosts themselves (aka transparent snapshots).
I have set up Networker in our VMware demo environment using the Networker OVF and the vProxy OVF. It connects to a Data Domain using a boost account in an snmp community. The vProxy is running fine and accessing the individual VMs. I've configured a vProxy policy and workflow with a backup action to send one of the environments VMs to the DD system and all seems fine. When I run the workflow and check the only messages it reads is "starting workflow" and "workflow succeeded". In the policy_notifications.log file it says its duration was 0 hours/mins/seconds and when I try and run the same workflow from the vcenter plug-in it says "successfully started policy" and then nothing shows up in the tasks list. The policy_notifications.log file also reveals that the NVE backup which comes preconfigured on the system has been failing with 0 successful backups.  Any ideas why this might be happening? 
Networker vProxy to DD policy running successfully but nothing happens.