DNAT traffic is not working if SNAT is Disabled.

DNAT traffic is getting dropped at Table 21 (L3_FIB_TABLE) since if SNAT is disabled there is no default flow table 21->table 26 is getting installed on the switch for carry DNAT traffic.

Please find the below steps for re-produce the issue.

1) Create Network 1 and network 2
2) Create Subnet1 from Network1 and Subnet2 from Network2
3) Create Neutron port for each network
4) Boot VMs on each network with different compute nodes
5) Create Router1
6) Attach subnet1 and subnet2 to the neutron-router1
7) Create External network (GRE Provider type)
8) Create external subnet
9) Create L3BGP-VPN and associate to external network
10) Router gateway set with disabled SNAT (neutron router-gateway-set router1 myextnet100 --enable-snat)

11) Create 2 FloatingIP
12) Associate FloatingIP to VM Instance Neutron port
13) Ping from FIP-1 to FIP-2 (Traffic is not working because of missing flows in Table 21)