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Thank you Slawek, Seán, Ryan, Miguel.
We’ll get to work on this new refactoring, legacy router implementation and the missing unit/functional tests. We’re setting lower priority to the scenario job but hopefully it can be done in stein-3 as well.

Best regards,
Igor D.C.

From: Miguel Lavalle <miguel at mlavalle.com>
Sent: Friday, February 1, 2019 5:07 PM
To: openstack-discuss at lists.openstack.org
Subject: Re: [neutron] OVS OpenFlow L3 DVR / dvr_bridge agent_mode

Hi Igor,

Please see my comments in-line below

On Tue, Jan 29, 2019 at 1:26 AM Duarte Cardoso, Igor <igor.duarte.cardoso at intel.com<mailto:igor.duarte.cardoso at intel.com>> wrote:
Hi Neutron,

I've been internally collaborating on the ``dvr_bridge`` L3 agent mode [1][2][3] work (David Shaughnessy, Xubo Zhang), which allows the L3 agent to make use of Open vSwitch / OpenFlow to implement ``distributed`` IPv4 Routers thus bypassing kernel namespaces and iptables and opening the door for higher performance by keeping packets in OVS for longer.

I want to share a few questions in order to gather feedback from you. I understand parts of these questions may have been answered in the past before my involvement, but I believe it's still important to revisit and clarify them. This can impact how long it's going to take to complete the work and whether it can make it to stein-3.

1. Should OVS support also be added to the legacy router?
And if so, would it make more sense to have a new variable (not ``agent_mode``) to specify what backend to use (OVS or kernel) instead of creating more combinations?

I would like to see the legacy router also implemented. And yes, we need to specify a new config option. As it has already been pointed out, we need to separate what the agent does in each host from the backend technology implementing the routers.


2. What is expected in terms of CI for this? Regarding testing, what should this first patch include apart from the unit tests? (since the l3_agent.ini needs to be configured differently).

I agree with Slawek. We would like to see a scenario job.


3. What problems can be anticipated by having the same agent managing both kernel and OVS powered routers (depending on whether they were created as ``distributed``)?
We are experimenting with different ways of decoupling RouterInfo (mainly as part of the L3 agent refactor patch) and haven't been able to find the right balance yet. On one end we have an agent that is still coupled with kernel-based RouterInfo, and on the other end we have an agent that either only accepts OVS-based RouterInfos or only kernel-based RouterInfos depending on the ``agent_mode``.

I also agree with Slawek here. It would a good idea if we can get the two efforts in synch so we can untangle RouterInfo from the agent code


We'd also appreciate reviews on the 2 patches [4][5]. The L3 refactor one should be able to pass Zuul after a recheck.

[1] Spec: https://blueprints.launchpad.net/neutron/+spec/openflow-based-dvr
[2] RFE: https://bugs.launchpad.net/neutron/+bug/1705536
[3] Gerrit topic: https://review.openstack.org/#/q/topic:dvr_bridge+(status:open+OR+status:merged)
[4] L3 agent refactor patch: https://review.openstack.org/#/c/528336/29
[5] dvr_bridge patch: https://review.openstack.org/#/c/472289/17

Thank you!

Best regards,
Igor D.C.

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