Last week I was troubleshooting neutron issues, and one of my colleagues showed me a new cool tool to help debug some issues.
Here is the link to the tool and its current documentation:

Basic usage:

Get a neutron network UUID:

neutron net-list

Add a probe to on the network:

neutron-debug --config-file <config file for l3 agent> probe-create <network UUID>
neutron-debug --config-file /etc/neutron/l3_agent.ini probe-create 81abae05-657d-4dc9-ad30-c42f5b7d0c75

List network namespaces:

$ ip netns

List probes:

neutron-debug --config-file /etc/neutron/l3_agent.ini probe-list

Use the newly created probe to ping all the things on the network (if it is not working, you need to update neutron-debug):

neutron-debug --config-file /etc/neutron/l3_agent.ini ping-all 43d574f6-ee34-43d8-a3b4-4c7e686312cb

Delete the probe:

neutron-debug --config-file /etc/neutron/l3_agent.ini probe-delete 43d574f6-ee34-43d8-a3b4-4c7e686312cb

Cleanup net spaces:

$ neutron-netns-cleanup --force --config-file=/etc/neutron/dhcp_agent.ini --config-file=/etc/neutron/neutron.conf
$ neutron-netns-cleanup --force --config-file=/etc/neutron/l3_agent.ini --config-file=/etc/neutron/neutron.conf