[openstack-dev] [Neutron] DVR + L3 HA + L2pop - Mapping out the work

Duarte, Adolfo adolfo.duarte at hpe.com
Wed Dec 9 01:45:21 UTC 2015

I agree with your comments below. 

I hope we are not going to hold off on this patch, since we need to address the other issues. It makes sense to have a separate tag in the Launchpad to couple all the l3-ha-dvr-l2pop issues into a single bucket and track it to completion.

The patch in question (143169) is only half of the solution. 143169 is the server side of the code. 

The agent side has already merged, and there are several parties waiting for the servers side so they can start evaluating and testing the solution.  I know that this can be done by pulling the patch itself but the problem with that is that until it is merged the patch status is not really "frozen". In other words, without the merge, there is no assurance that something will not come in at the last minute and change its functionality and break it, or that more defects are introduce due to the constant refactoring to keep it out of merge conflict. 

By merging the patch right now we give ourselves enough time to solve any issues that might arise. When fixes for the defects below are worked out they will automatically be tested and verified against dvr/ha. 

In worst case scenario this patch can be reverted; but if we wait too  long to merge it, we might paint ourselves into a corner.  

Let us merge this patch and that would allow the users to test the server side and agent side for further evaluation. We can address any issues that come along with enough time to either fix them, make any necessary redesigns, or revert it.

Adolfo Duarte
-----Original Message-----
From: Assaf Muller [mailto:amuller at redhat.com] 
Sent: Friday, December 04, 2015 2:46 PM
To: OpenStack Development Mailing List (not for usage questions)
Subject: [openstack-dev] [Neutron] DVR + L3 HA + L2pop - Mapping out the work

There's a patch up for review to integrate DVR and L3 HA:

Let me outline all of the work that has to happen before that patch would be useful:

In order for DVR + L3 HA to work in harmony, each feature would have to be stable on its own. DVR has its share of problems, and this is being tackled full on, with more folks joining the good fight soon. L3 HA also has its own problems:

* https://review.openstack.org/#/c/238122/
* https://review.openstack.org/#/c/230481/
* https://review.openstack.org/#/c/250040/

DVR requires l2pop, and l2pop on its own is also problematic (Regardless if DVR or L3 HA is turned on). One notable issue is that it screws up live migration:
I'd really like to see more focus on Vivek's patch that attempts to resolve this issue:

Finally the way L3 HA integrates with l2pop is not something I would recommend in production, as described here:
https://bugs.launchpad.net/neutron/+bug/1522980. If I cannot find an owner for this work I will reach out to some folks soon.

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