Documentation
https://docs.openstack.org/neutron/latest/admin/config-address-scopes.html

openstack address scope create --share --ip-version 4 test-scope-v4

openstack subnet pool create --share --pool-prefix 10.0.0.0/8 --default-prefix-length 24 --address-scope test-scope-v4 test-subnet-pool-v4

openstack network create test-network2

openstack subnet create --network test-network2 --subnet-pool test-subnet-pool-v4 test-subnet2

openstack network show test-network2

# disable address scope
openstack subnet pool set --no-address-scope provider-subnet-pool

# disable enable scope
openstack subnet pool set --address-scope provider-addr-scope-v4 provider-subnet-pool

Debug Iptables

ssh -t control1-dev sudo ip netns exec qrouter-cca1d315-c56e-41ed-9a4d-1af6ca092f1a bash

iptables -S
...
-A neutron-l3-agent-scope -o qr-80ae710a-ec -m mark ! --mark 0x4000000/0xffff0000 -j DROP

iptables -t mangle -n -v -L neutron-l3-agent-scope

iptables -t filter -vL neutron-l3-agent-scope

iptables -t mangle -vL neutron-l-agent -POSTROUTING
iptables -t nat -vL neutorn-l3-agent-snat

Network segments

openstack network segment list

Links
https://www.youtube.com/watch?v=VsCYSZUOB6U