Delegating and routing an IPv6 prefix to an instance

Brian Haley at
Mon Jun 29 17:55:12 UTC 2020

On 6/29/20 11:10 AM, Christian Rohmann wrote:
> On 2020-06-26 20:16, Brian Haley wrote:
>> The Neutron implementation of IPv6 PD doesn't support the use case
>> you're describing, allocating an entire /64 to a device/neutron port.
>> The Neutron router can only do PD, then advertise the /64 it received
>> on a downstream IPv6 subnet.  While this does give the instance an
>> IPv6 address that is globally unique, it's just the single address.
> Thanks for your reply and the time to look into this!
> It might be a bit of a leap, but would this feature not be similar to a
> floating public IP which I can assign to an instance in the IPv4 world?
> Certainly with virtually unlimited globally unique IPv6 space there is
> no need for this in regards to the IPv6 prefixes an instance receives to
> be reachable - they could all have globally routed and reachable
> addresses if need be.
> But some sort of pool of "additional" <s>public</s> globally unique
> prefixes that can be requested, bound and routed to an instance would be
> nice - kinda like
> .

We made a conscious decision to not support floating IPv6 in the base 
reference implementation, although it is available in one of the 
third-party drivers (Midonet?).  Making the tenant IPv6 subnets 
reachable directly was instead the goal, which happens when PD is used.

> What would be the process of getting such a feature into a working
> specification in case one was interested in implementing this?

It's outlined in the neutron docs, but basically it starts with a bug 
describing the feature you'd like to add, it's then discussed at a 
weekly meeting each Friday.


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