Hi Genhart,
Very interesting design. Where did you get this idea from?
I played with it for a while and I was able to make it work on firefly 12.1X47-D35.2 after I added proxy-arp statement under logical interface level. After adding proxy-arp under logical interfaces and not security nat it started to work.
set interfaces reth0 vlan-tagging
set interfaces reth0 redundant-ether-options redundancy-group 1
set interfaces reth0 unit 10 proxy-arp
set interfaces reth0 unit 10 vlan-id 10
set interfaces reth0 unit 10 family inet unnumbered-address lo0.0
set interfaces reth0 unit 20 proxy-arp
set interfaces reth0 unit 20 vlan-id 20
set interfaces reth0 unit 20 family inet unnumbered-address lo0.0
Session ID: 47, Policy name: default-policy-00/2, State: Active, Timeout: 1792, Valid
In: 172.31.15.20/40204 --> 172.31.15.10/22;tcp, If: reth0.20, Pkts: 23, Bytes: 3541
Out: 172.31.15.10/22 --> 172.31.15.20/40204;tcp, If: reth0.10, Pkts: 26, Bytes: 4624
Regards, Wojtek