npf: Redundancy and load balancing

[Sunil Nimmagadda <sunil%nimmagadda.net@localhost>]

One of the items from npf task list[0] mentions...
"Redundancy and load balancing: initially, add state replication
and replace in-kernel CARP/VRRP with an userlevel daemon. Note: we
probably want to eliminate proplib in NPF before doing this."

I am interested in this feature and would like to explore and
seek guidance for an implementation. It would be great to know...

1. If someone already attempted implementing it. AFAICS, nothing in
-current, most likely a branch somewhere in hg?

2. If the approach is still the preferred way to go. The last
update to this document is from a few years ago.

3. If the proposed userlevel daemon should implement VRRP or
CARP?

4. If npfd(8) should be extended to broadcast/listen for state
changes. (manpage mentions state synchronization)

[0] https://www.netbsd.org/~rmind/npf/__tasklist.html