PPDM with dedicated network backup

on vmware we have vswitch for management and production network and one vcswitch for backup because backup network is not routed

do you actually want/need a proxy with PPDM or do you intend to use TSDM (transparent snapshots)? The latter is more limited, as it doesn't offer quiescing, so proxy based backup is indeed what you are after?

https://www.dell.com/support/kbdoc/en-us/000205869/how-to-setup-ppdm-multi-vlan-network shows an example (the video is more extensive) that the proxy (or as PPDM calls them "protection engine") has two nics, where besides the management interface there is a 2nd interface in the same subnet that the DD is located into, however when having a routed network, you would not want or even need the DD to have an interface itself in the same network that the assets to protected are in or that the proxy itself is in?

So might need some manual fiddling, by deploying a protection engine and maybe do some manual editing of the required routing after the fact? For NW the same was required as one could add a 2nd interface (the 1st nic of a vproxy always needs to be the one that the NW server connects to to manage the NW vproxy), but if that "backup" interface was not in the same subnet as the DD's were located in, then it required creating an additional route for that 2nd nic.

But if you proxy would be (also) located in the same subnet as the DD, it might just be enough to add a 2nd nic, besides the management nic.

https://www.dell.com/support/manuals/en-us/powerprotect-software/pp-dm_19.17_virtual_machines_ug/add-a-vm-direct-engine-for-virtual-machine-kubernetes-cluster-or-nas-protection?guid=guid-74c13079-cc2a-47dd-9360-7ce7fdca8a9c&lang=en-us