network: ~$ ip netns | grep qrouter
qrouter-a6dd3417-df21-433b-8857-827e895ea3c6
qrouter-3e810636-1f43-4d08-acc2-2edb25a10e0e

network: ~$ sudo ip netns exec qrouter-3e810636-1f43-4d08-acc2-2edb25a10e0e route -n
...
0.0.0.0         172.20.6.1      0.0.0.0         UG    0      0        0 qg-900380a6-98
10.5.5.0        0.0.0.0         255.255.255.0   U     0      0        0 qr-52a0ab1a-31
172.20.6.0      0.0.0.0         255.255.255.0   U     0      0        0 qg-900380a6-98

network: ~$ sudo ip netns exec qrouter-3e810636-1f43-4d08-acc2-2edb25a10e0e iptables-save
...
-A neutron-l3-agent-snat -j neutron-l3-agent-float-snat
-A neutron-l3-agent-snat -s 10.5.5.0/24 -j SNAT --to-source 172.20.6.31
-A neutron-postrouting-bottom -j neutron-l3-agent-snat