As Slawek Kaplonski told me, I enabled neutron debugging and I didn't find why specific mechanism drivers are refusing to bind ports
on that host.

I noticed that the VM can get an IP from DHCP, I see a link on the web interface (network topology) between my physical network "provider" and the VM. But this link disappeared when the VM crashed due to the error.

Here are the previous DEBUG logs, just before the ERROR one.

I don't succeed in getting more informed by these logs. (/neutron/server.log)

Thank you a lot for your time !
Maxime

`2021-04-07 10:10:30.294 25623 DEBUG neutron.pecan_wsgi.hooks.policy_enforcement [req-a995e8eb-fde4-49be-b822-29f7e98b56d4 9c53e456ca2d4d07a4aecbf91c487cae d26b6143299a47e3a77feff04ae8b7a1 - default default] Attributes excluded by policy engine: ['binding:profile', 'binding:host_id', 'binding:vif_type', 'binding:vif_details'] _exclude_attributes_by_policy /usr/lib/python3/dist-packages/neutron/pecan_wsgi/hooks/policy_enforcement.py:256

2021-04-07 10:10:30.995 25626 DEBUG neutron.pecan_wsgi.hooks.policy_enforcement [req-706ad36e-31a1-4e5a-b9f6-17951ccb089a 9c53e456ca2d4d07a4aecbf91c487cae d26b6143299a47e3a77feff04ae8b7a1 - default default] Attributes excluded by policy engine: ['binding:profile', 'binding:host_id', 'binding:vif_type', 'binding:vif_details'] _exclude_attributes_by_policy /usr/lib/python3/dist-packages/neutron/pecan_wsgi/hooks/policy_enforcement.py:256

2021-04-07 10:10:31.105 25626 DEBUG neutron.pecan_wsgi.hooks.policy_enforcement [req-446ed89e-0697-4822-b69b-49b02ad9732d 9c53e456ca2d4d07a4aecbf91c487cae d26b6143299a47e3a77feff04ae8b7a1 - default default] Attributes excluded by policy engine: ['binding:profile', 'binding:host_id', 'binding:vif_type', 'binding:vif_details'] _exclude_attributes_by_policy /usr/lib/python3/dist-packages/neutron/pecan_wsgi/hooks/policy_enforcement.py:256

2021-04-07 10:10:31.328 25623 DEBUG neutron.api.v2.base [req-05e6a5c3-f5b4-45f4-8339-fbfa2a7eed8a b21b8901642c470b8f668965997c7922 0f23d567d2ce4599a1571d8fd5982f9a - default default] Request body: {'port': {'device_id': '6406a1b1-7f0b-4f8e-88dd-81dcded8299d', 'device_owner': 'compute:nova', 'binding:host_id': 'compute1'}} prepare_request_body /usr/lib/python3/dist-packages/neutron/api/v2/base.py:716

2021-04-07 10:10:31.980 25623 DEBUG neutron.plugins.ml2.managers [req-05e6a5c3-f5b4-45f4-8339-fbfa2a7eed8a b21b8901642c470b8f668965997c7922 0f23d567d2ce4599a1571d8fd5982f9a - default default] Attempting to bind port 2e702d95-34df-4b85-9206-75c28bbcb9da on host compute1 for vnic_type normal with profile bind_port /usr/lib/python3/dist-packages/neutron/plugins/ml2/managers.py:747

2021-04-07 10:10:31.981 25623 DEBUG neutron.plugins.ml2.managers [req-05e6a5c3-f5b4-45f4-8339-fbfa2a7eed8a b21b8901642c470b8f668965997c7922 0f23d567d2ce4599a1571d8fd5982f9a - default default] Attempting to bind port 2e702d95-34df-4b85-9206-75c28bbcb9da on host compute1 at level 0 using segments [{'id': 'a35c88a5-2234-4b2f-bab6-a5a17af42d1e', 'network_type': 'flat', 'physical_network': 'provider', 'segmentation_id': None, 'network_id': '45320836-f1a3-4e96-a3d8-59b95d633d1e'}] _bind_port_level /usr/lib/python3/dist-packages/neutron/plugins/ml2/managers.py:768

2021-04-07 10:10:31.981 25623 ERROR neutron.plugins.ml2.managers [req-05e6a5c3-f5b4-45f4-8339-fbfa2a7eed8a b21b8901642c470b8f668965997c7922 0f23d567d2ce4599a1571d8fd5982f9a - default default] Failed to bind port 2e702d95-34df-4b85-9206-75c28bbcb9da on host compute1 for vnic_type normal using segments [{'id': 'a35c88a5-2234-4b2f-bab6-a5a17af42d1e', 'network_type': 'flat', 'physical_network': 'provider', 'segmentation_id': None, 'network_id': '45320836-f1a3-4e96-a3d8-59b95d633d1e'}] `



Le jeu. 1 avr. 2021 à 21:36, Slawek Kaplonski <skaplons@redhat.com> a écrit :
Hi,

Dnia czwartek, 1 kwietnia 2021 14:44:21 CEST Maxime d'Estienne pisze:
> Hello,
>
> I spent a lot of time troubleshooting my issue, which I described here :
> https://serverfault.com/questions/1058969/cannot-create-an-instance-due-to-failed-binding
>
> To summarize, when I want to create an instance, binding fails on compute
> node, the dhcp agent seems to give an ip to the VM but I have an error.

What do You mean exactly? Failed binding of the port in Neutron? In such case
nova will not boot vm so it can't get IP from DHCP.

>
> I don't know where to dig, besides what I have done.

Please enable debug logs in neutron-server and look in its logs for the reason
why it failed to bind port on specific host.
Usually reason is dead L2 agent on host or mismatch in the agent's bridge
mappings configuration in the agent.

>
> Thanks a lot for your help !


--
Slawek Kaplonski
Principal Software Engineer
Red Hat