Using vlan external netowrk fip，dragonflow dirtributed dnat does not work

My problem is :
 Dragonflow distributed dnat can work ok when external network type is vlan ? if ok ,dragonflow distributed dnat support two or more external vlan network ?

Details flollow:

1. Using flat external netowork fip ， dragonflow distributed dnat work fine

   +------------------------------------------------------+ +----------------------------------+
   | | | MARK: C |
   | br-ex enp0s3 |XXXXXXXX| 192.168.56.10 |
   | 08:00:27:12:3f:5b | | external network gateway |
   | 192.168.56.155 | | |
   +------------------------------------------------------+ +----------------------------------+
                       |
                       |
                       |
                       |
                       |
                       |
                       |
      +-----------------------------------------------------------+ flows: A -> br-int(dnat) -> br-ex(l3 forward) -> C
      | |
      | |
      | br-int |
      | |
      | |
      +-----------------------------------------------------------+
                                |
                                |
                                | fa:16:3e:d4:60:2d
                                | flat floating ip 192.168.56.55
                                | dragonflow distribute dnat
                                |
                       +--------------------+
                       | 1.1.1.6 |
                       | Mark: A |
                       | |
                       | |
                       +--------------------+

Instructions：
192.168.56.0/24 is my external flat network subnet.
using dragonflow dnat
A->C icmp flows: A -> br-int(dnat) -> br-ex(l3 forward) -> C

1.1.1.6 with fip ping gateway.( A->C connected). When icmp packet arrived at br-ex , layer3 forwarding is noraml.

 Catch packets in br-ex interface.

tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on br-ex, link-type EN10MB (Ethernet), capture size 262144 bytes
21:40:50.340646 fa:16:3e:d4:60:2d > 08:00:27:12:3f:5b, ethertype IPv4 (0x0800), length 98: 192.168.56.55 > 114.114.114.114: ICMP echo request, id 22785, seq 188, length 64
21:40:50.340672 08:00:27:12:3f:5b > be:e5:f2:da:42:46, ethertype IPv4 (0x0800), length 98: 192.168.56.55 > 114.114.114.114: ICMP echo request, id 22785, seq 188, length 64
21:40:51.341668 fa:16:3e:d4:60:2d > 08:00:27:12:3f:5b, ethertype IPv4 (0x0800), length 98: 192.168.56.55 > 114.114.114.114: ICMP echo request, id 22785, seq 189, length 64
21:40:51.341696 08:00:27:12:3f:5b > be:e5:f2:da:42:46, ethertype IPv4 (0x0800), length 98: 192.168.56.55 > 114.114.114.114: ICMP echo request, id 22785, seq 189, length 64

2. Using vlan external netowrk fip，dragonflow dirtributed dnat does not work

       +------------------------------------------------------+ +----------------------------------+
       | | | MARK: C |
       | br-ex enp0s3 |XXXXXXXX| 192.168.57.10 |
       | 08:00:27:12:3f:5b | | external vlan network gateway |
       | 192.168.56.155 | | |
       +------------------------------------------------------+ +----------------------------------+
                           |
                           | +
                           | |
                           | |
                           | |
                           | |
                           | v
          +-----------------------------------------------------------+ flows: A -> br-int(dnat) -> br-ex(l3 forward) -> C
          | |
          | |
          | br-int | work err here
          | |
          | |
          +-----------------------------------------------------------+
                                    |
                                    |
                                    | fa:16:3e:39:63:c2
                                    | vlan external network fip : 192.168.57.159
                                    |
                                    |
                           +--------------------+
                           | 1.1.1.6 |
                           | Mark: A |
                           | |
                           | |
                           +--------------------+

 Catch packets in br-ex interface. and I find that icmp packet can not be l3 forwarded in br-ex . A -> c disconnect.

stack@p-controller:~/devstack$ sudo tcpdump -i br-ex -ne
tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
listening on br-ex, link-type EN10MB (Ethernet), capture size 262144 bytes
21:58:36.278770 fa:16:3e:39:63:c2 > 08:00:27:12:3f:5b, ethertype 802.1Q (0x8100), length 102: vlan 207, p 0, ethertype IPv4, 192.168.57.159 > 114.114.114.114: ICMP echo request, id 23041, seq 15, length 64
21:58:37.279352 fa:16:3e:39:63:c2 > 08:00:27:12:3f:5b, ethertype 802.1Q (0x8100), length 102: vlan 207, p 0, ethertype IPv4, 192.168.57.159 > 114.114.114.114: ICMP echo request, id 23041, seq 16, length 64
21:58:38.279781 fa:16:3e:39:63:c2 > 08:00:27:12:3f:5b, ethertype 802.1Q (0x8100), length 102: vlan 207, p 0, ethertype IPv4, 192.168.57.159 > 114.114.114.114: ICMP echo request, id 23041, seq 17, length 64

So my problem is :
 Dragonflow distributed dnat can work ok when external network type is vlan ? if ok ,dragonflow distributed dnat support two or more external vlan network ?