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<p>"I'm partial to an "agent_mode" flag which will toggle the
router..."</p>
<p>In my previous email I mention being in favor of not overloading
agent_mode, I realized I had a typo that might be confusing. I'm
partial to introducing something like "agent_backend" for toggling
OVS vs. namespace routers, not "agent_mode". Sorry for the typo.</p>
<p>-Ryan<br>
</p>
<div class="moz-cite-prefix">On 1/31/19 10:02 AM, Ryan Tidwell
wrote:<br>
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<div class="moz-cite-prefix">On 1/29/19 1:25 AM, Duarte Cardoso,
Igor wrote:<br>
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<p class="MsoNormal">Hi Neutron,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">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.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">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.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">1. Should OVS support also be added to
the legacy router?<o:p></o:p></p>
<p class="MsoNormal">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?</p>
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</blockquote>
Personally, I would like to see all routers implemented completely
in the OVS data path. We can't do everything at once, so the
DVR-first approach here seems reasonable to me. As to the question
of config flags, agent_mode has a specific meaning. It effectively
tells the agent what role it's playing (SNAT, SNAT_HA, etc.), not
how to do it. dvr_bridge isn't a new mode, it's really a change to
the backend implementation of the router (ie the "how"). Because
of that, I'm partial to an "agent_mode" flag which will toggle the
router implementation between OVS and namespace implementations.<br>
<blockquote type="cite"
cite="mid:E09EC9A2DDB2914E953966C44BEF9CF633F86A76@ORSMSX103.amr.corp.intel.com">
<div class="WordSection1">
<p class="MsoNormal"><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">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).<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">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``)?<o:p></o:p></p>
<p class="MsoNormal">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``.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">We'd also appreciate reviews on the 2
patches [4][5]. The L3 refactor one should be able to pass
Zuul after a recheck.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">[1] Spec: <a
class="moz-txt-link-freetext"
href="https://blueprints.launchpad.net/neutron/+spec/openflow-based-dvr"
moz-do-not-send="true">https://blueprints.launchpad.net/neutron/+spec/openflow-based-dvr</a><o:p></o:p></p>
<p class="MsoNormal">[2] RFE: <a
class="moz-txt-link-freetext"
href="https://bugs.launchpad.net/neutron/+bug/1705536"
moz-do-not-send="true">https://bugs.launchpad.net/neutron/+bug/1705536</a><o:p></o:p></p>
<p class="MsoNormal">[3] Gerrit topic:
<a class="moz-txt-link-freetext"
href="https://review.openstack.org/#/q/topic:dvr_bridge+(status:open+OR+status:merged)"
moz-do-not-send="true">https://review.openstack.org/#/q/topic:dvr_bridge+(status:open+OR+status:merged)</a><o:p></o:p></p>
<p class="MsoNormal">[4] L3 agent refactor patch: <a
class="moz-txt-link-freetext"
href="https://review.openstack.org/#/c/528336/29"
moz-do-not-send="true">https://review.openstack.org/#/c/528336/29</a><o:p></o:p></p>
<p class="MsoNormal">[5] dvr_bridge patch: <a
class="moz-txt-link-freetext"
href="https://review.openstack.org/#/c/472289/17"
moz-do-not-send="true">https://review.openstack.org/#/c/472289/17</a><o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thank you!<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span lang="EN-IE">Best regards,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-IE">Igor D.C.<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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</blockquote>
-Ryan<br>
</blockquote>
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