Open Stack

Hello, Rodolfo,

I have relevant information on one of the points discussed below, so
just wanted to chime in.

On Tue, Jun 20, 2023 at 12:44 PM Rodolfo Alonso Hernandez
<ralonsoh at redhat.com> wrote:

[ snip ]

> *** 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.

Background on why this is happening and a solution is being worked on in [5].

5: https://review.opendev.org/c/openstack/neutron/+/874760

--
Frode Nordahl

> *** 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].
>
> *** 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.
>
>
> 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-dvr.html
> [2]https://review.opendev.org/c/openstack/neutron/+/867513
> [3]https://github.com/openstack/neutron/blob/cbb89fdb1414a1b3a8e8b3a9a4154ef627bb9d1a/neutron/agent/metadata/agent.py#L89
> [4]https://ltomasbo.wordpress.com/2021/06/25/openstack-networking-with-evpn/
>


-- 
Frode Nordahl