Just adding a couple of pointers below On Tue, Jun 20, 2023 at 12:53 PM Rodolfo Alonso Hernandez < ralonsoh@redhat.com> wrote:
Hello all:
Thank you for joining us during the Forum session and the PTG slots. It was very productive and we were able to check the pulse of OpenStack and Neutron in particular.
This time both the Forum session and the PTG were attended mainly by operators and users; the number of developers was reduced and this is something we need to improve. A healthy community is nourished by the active participation of their members, not only pushing new code but reviewing and helping fixing the new bugs.
=== Forum session === That was a good surprise for me to find so many people in the room. I wasn't expecting that after checking the etherpad link provided before the meeting. During this short session, focused on issues/pain points of Neutron, we could find out that: * The ML2/OVN backend is increasing its adoption rate. * Most users have deployments between Wallaby and Antelope. * Hardware offload is increasing its demand due to the network BW increasing requirements. * BGP/eVPN is deployed in most of the environments.
From this session I would highlight some lessons learned for next events: * If the Forum session time slot is reduced (30 mins), the attendant interventions should be limited to 2-3 minutes, enough to describe the issue. Any further discussion should be taken in the PTG sessions. * Request attendance "checkin" in the etherpad, to be prepared for the event. * Request people to add their questions in the etherpad in advance.
=== PTG === We didn't have technical sessions but many questions about issues and possible bugs. These are the most relevant ones:
*** OVN L3 scheduler issue *** This issue has been reproduced in an environment with more than 5 chassis with gateway ports. The router GW ports are assigned to the GW chassis using a manual scheduler implemented in Neutron (the default one is ``OVNGatewayLeastLoadedScheduler``). If one of the chassis is stopped, the GW ports should be re-assigned to the other GW chassis. This is happening but all ports fall under the same one; this re-scheduling should share the ports among the other active chassis. * Action item: I'll open a LP bug and investigate this issue.
*** Size of the OVN SB "HA_Chassis_Group" table *** The OVN SB "HA_Chassis_Group" increases its size indefinitely with each operation creating a router and assigning a new external gateway (external network). This table never decreases, * Action item: I'll open a LP bug, investigate this issue and if this is a core OVN issue, report it.
*** Live migration with ML2/OVN *** This is a common topic and not only for ML2/OVN. The migration time has many factors (memory size, applications running, network BW, etc) that could slow down the migration time and trigger a communication gap during this process. * Action item: to create better documentation, both in Nova and Neutron, about the migration process, what has been done to improve it (for example, the OVN multiple port binding) and what factors will affect the migration.
*** ML2/OVN IPv6 DVR *** This spec was approved during the last cycle [1]. The implementation [2] is under review. * Action item: to review the patch (for Neutron reviewers) * Action item: to implement the necessary tempest tests (for the feature developers)
*** BGP with ML2/OVS, exposing address blocks *** This user has successfully deployed Neutron with ML2/OVS and n-d-r. This user is currently making public a certain set of FIPs. However, for other VMs without FIPs, the goal is to make the router GW port IP address public, using the address blocks functionality; this is not working according to the user. * Action item: (for this user) to create a LP bug describing the architecture of the deployment, the configuration used and the API commands used to reproduce this issue.
*** Metadata service (any backend) *** Neutron is in charge of deploying the Metadata service on the compute nodes. Each time the metadata HTTP server is called, it requests from the Neutron API the instance and tenant ID [3]. This method implies a RPC call. In "busy" compute nodes, where the VMs are created and destroyed very fast, this RPC communication is a bottleneck. * Action item: open a LP bug to implement the same ``CacheBackedPluginApi`` used in the OVS agent. This RPC cached class creates a set of subscriptions to the needed resources ("ports" in this case). The Neutron API will send the port updated info and cached locally; that makes unnecessary the RPC request if the resources are stored locally.
*** ML2/OVN + Ironic nodes *** This user has deployed ML2/OVN with Ironic nodes, and is using ovn-bgp-agent with the eVPN driver to make public the private ports (IP and MACs) to the Ironic node ports. More information in [4].
There is an initial WIP implementation to add support for L2vni/evpn to the BGP driver, currently under review here [1]
*** BGP acceleration in ML2/OVN *** Many questions related to this topic, both with DPDK and HW offload. I would refer (once the link is available) to the talk "Enabling multi-cluster connectivity using dynamic routing via BGP in Openstack" given by Christophe Fontaine during this PTG. You'll find it very interesting how this new implementation moves all the packet processing to the OVS datapath (removing any Linux Bridge / iptables processing). The example provided in the talk refers to the use of DPDK.
The idea for the ovn-bgp-agent for this is described in [2], and initial (WIP) implementation is in [3] [1] https://review.opendev.org/c/openstack/ovn-bgp-agent/+/886090 [2] https://ltomasbo.wordpress.com/2023/01/09/how-to-make-the-ovn-bgp-agent-read... [3] https://review.opendev.org/c/openstack/ovn-bgp-agent/+/881779
I hope this PTG was interesting for you! Don't hesitate to use the usual channels that are the mailing list and IRC. Remember we have the weekly Neutron meeting every Tuesday at 1400UTC.
Regards.
[1] https://specs.openstack.org/openstack/neutron-specs/specs/2023.1/ovn-ipv6-dv... [2]https://review.opendev.org/c/openstack/neutron/+/867513 [3] https://github.com/openstack/neutron/blob/cbb89fdb1414a1b3a8e8b3a9a4154ef627... [4] https://ltomasbo.wordpress.com/2021/06/25/openstack-networking-with-evpn/
-- LUIS TOMÁS BOLÍVAR Principal Software Engineer Red Hat Madrid, Spain ltomasbo@redhat.com