[ovs-dev] [PATCH v2] ovn-sb.ovsschema: Avoid duplicated IPs in Encap table.

[Ben Pfaff]

On Tue, Nov 13, 2018 at 11:25:59AM -0800, Han Zhou wrote:
> From: Han Zhou <hzhou8 at ebay.com>
> 
> When adding a new chassis, if there is an old chassis with same IP
> existed in Encap table, it is allowed to be added today. However,
> allowing it to be added results in problems:
> 
> 1. The new chassis cannot work because none of the other chassises
>    are able to create tunnel to it, because of the IP confliction
>    with already existed tunnel to the old chassis.
> 
> 2. All the other chassises will continuously retry creating the tunnel
>    and complaining about the error.
> 
> So, instead of hiding the problem, it is better to expose it while
> trying to add the second chassis with duplicated IP. This patch
> ensures it from the ovsdb schema.
> 
> Signed-off-by: Han Zhou <hzhou8 at ebay.com>

I'm worried that this will make it hard for users to upgrade: if they
have any duplicate chassis, then they will have to manually delete them
before ovsdb-server will accept the new database.

I think you mentioned that ovn-controller can't delete the duplicates
because of RBAC permissions.  What if ovn-northd deletes them instead?
If it doesn't have a way to know which one is the "correct" one, it
could just delete all of the duplicates, since the ovn-controller that
is actually running will re-create its chassis if it disappears.