I did some digging and cannot find anything satisfactory for this bit of tribal knowledge re: Mitaka and IPv6.

From email, IRC, phab, and conference notes I think:

* This comes from around Kilo time when IPv6 was first being introduced and it was described as planning to be ready for general deploy in Newton. This is just a note I have from that time.

* BGP for Neutron routers and an upstream is seemingly only a serious option starting in Mitaka and I believe we talked about not wanting to plan on implementing both at once so probably that doubled down on the Newton narrative.

* At the time we started kicking this around it was unclear what the relationship was going to be between VXLAN (or other overlays) and IPv6. AFAICT overlays still require the host to use IPv4 even if the tenants are on IPv6, which is OK. It seems like ironically IPv6 within the Cloud is tested much better than IPv6 for control plane components.

* I have a note that indicates Router HA is not viable for IPv6 in Mitka with prefix designation https://docs.openstack.org/mitaka/networking-guide/config-ipv6.html. Whether this seriously matters probably depends on what the ideal model is here but in some dusty corner of my brain the idea that each tenant has globally unique IPv6 space via some overlay mechanism with HA software routers wouldn't work out it seems.

TLDR pre-Neutron things were very unclear what would even be possible

On Wed, Dec 12, 2018 at 5:36 AM Arturo Borrero Gonzalez <aborrero@wikimedia.org> wrote:

Hi,

I'm opening this email thread to try to get an overview of IPv6 in CloudVPS.

Several times I've heard that Openstack Mitaka wasn't the most
appropriate version to start doing IPv6.
However, I've read the config docs [0] and I didn't detect any major
issues at first.

@Chase, do you remember the issues you found?

Sooner or later, we will have to handle IPv6 in CloudVPS (and in
Toolforge), so a plan could be:

* design the ideal IPv6 model [1], with agreement from the main SRE team
* start doing tests in the labtestn deployment in codfw
* evaluate how this could be added to eqiad1 incrementally

Even if we must forget about IPv6 in Mitaka, we could start thinking on
the ideal model now.

[0] https://docs.openstack.org/mitaka/networking-guide/config-ipv6.html
[1]
https://wikitech.wikimedia.org/wiki/Portal:Cloud_VPS/Admin/Neutron_ideal_model

Chase Pettet

chasemp on phabricator and IRC