DHCP Relay through a GRE bridge

Diagram

Network Topology Diagram

Configuration

DHCP Server

set interfaces ethernet eth0 address '10.0.2.1/24'
set interfaces loopback lo address '192.168.3.3/24'
set interfaces tunnel tun100 address '172.16.0.2/30'
set interfaces tunnel tun100 encapsulation 'gretap'
set interfaces tunnel tun100 source-address '10.0.2.1'
set interfaces tunnel tun100 remote '192.168.0.1'
set protocols ospf area 0 network '192.168.3.0/24'
set protocols ospf area 0 network '10.0.2.0/24'
set protocols ospf parameters router-id '192.168.3.3'
set protocols static route 10.0.1.2/32 interface tun100
set service dhcp-server shared-network-name asdf authoritative
set service dhcp-server shared-network-name asdf subnet 192.168.3.0/24 range 0 start '192.168.3.30'
set service dhcp-server shared-network-name asdf subnet 192.168.3.0/24 range 0 stop '192.168.3.40'
set service dhcp-server shared-network-name asdf subnet 10.0.1.0/24 default-router '10.0.1.2'
set service dhcp-server shared-network-name asdf subnet 10.0.1.0/24 range 0 start '10.0.1.200'
set service dhcp-server shared-network-name asdf subnet 10.0.1.0/24 range 0 stop '10.0.1.210'
set service dhcp-server shared-network-name asdf subnet 10.2.1.0/24 range 0 start '10.2.1.222'
set service dhcp-server shared-network-name asdf subnet 10.2.1.0/24 range 0 stop '10.2.1.233'
set service dhcp-server shared-network-name asdf subnet 172.16.0.0/30 range 0 start '172.16.0.1'
set service dhcp-server shared-network-name asdf subnet 172.16.0.0/30 range 0 stop '172.16.0.2'

In-Between Router

set interfaces ethernet eth0 address '192.168.0.2/24'
set interfaces ethernet eth1 address '10.0.2.2/24'
set protocols ospf area 0 network '192.168.0.0/24'
set protocols ospf area 0 network '10.0.2.0/24'
set protocols ospf parameters router-id '192.168.0.2'

DHCP Relay

set interfaces ethernet eth0 address '10.0.1.2/24'
set interfaces ethernet eth1 address '192.168.0.1/24'
set interfaces loopback lo address '10.100.100.1'
set interfaces tunnel tun100 address '172.16.0.1/30'
set interfaces tunnel tun100 encapsulation 'gretap'
set interfaces tunnel tun100 source-address '192.168.0.1'
set interfaces tunnel tun100 remote '10.0.2.1'
set protocols ospf area 0 network '10.0.1.0/24'
set protocols ospf area 0 network '192.168.0.0/24'
set protocols ospf area 0 network '10.100.100.0/24'
set protocols ospf parameters router-id '10.100.100.1'
set protocols static route 192.168.3.3/32 interface tun100
set service dhcp-relay interface 'eth0'
set service dhcp-relay interface 'tun100'
set service dhcp-relay server '192.168.3.3'