Open Stack

Hi Marc-Antoine,

See inline...

On 3/8/22 11:18, Marc-Antoine Godde wrote:
> Hi,
> 
> Here’s what we’ve done.
> 
> We created a network:
> 
> Name
>     ipv6-testing-network
> ID
>     9d5ca309-1861-4422-bcff-8818f9762a6f
> Project ID
>     653f5a2e60d34768a8629e5d4fca0738
> Status
>     Active
> Admin State
>     UP
> Shared
>     Yes
> External Network
>     Yes
> MTU
>     1500
> Provider Network
>     Network Type: vlan
>     Physical Network: vlan
>     Segmentation ID: 51

So this is an external provider network connected to your datacenter 
network, correct? In the case Slawek was describing I believe he was 
talking about an internal private network, which when a neutron router 
is attached will trigger radvd to be spawned, etc.

In this case VMs booted on this network should be seeing RAs from your 
datacenter router, if it's sending them. If it's not that would explain 
why they only have a link-local IPv6 address since the neutron router 
will not spawn radvd to run on the external network.

BTW, I'm trying to compare this to my local setup, but since I'm not 
running Horizon just using 'openstack network show...', 'openstack 
subnet show...' output, which is slightly different, but looks to match 
what you're doing.

Is your plan to have private IPv6 subnets that are then routed to your 
external network or is this just a test?

-Brian


> We created a subnet:
> 
> Name
>     ipv6-testing-v6
> ID
>     763771d4-b9d7-419a-ba04-97ce3abaf152
> Project ID
>     653f5a2e60d34768a8629e5d4fca0738
> Network Name
>     ipv6-testing-network
> Network ID
>     9d5ca309-1861-4422-bcff-8818f9762a6f
>     <https://openstack.viarezo.fr/project/networks/9d5ca309-1861-4422-bcff-8818f9762a6f/detail>
> Subnet Pool
>     None
> IP Version
>     IPv6
> CIDR
>     xxxx:xxxx:2f1:aaaa::/64
> IP Allocation Pools
>     Start xxxx:xxxx:2f1:aaaa::2 - End xxxx:xxxx:2f1:aaaa:ffff:ffff:ffff:ffff
> Gateway IP
>     xxxx:xxxx:2f1:aaaa::1
> DHCP Enabled
>     Yes
> IPv6 Address Configuration Mode
>     SLAAC: Address discovered from OpenStack Router
> Additional Routes
>     None
> DNS Name Servers
>     None
> 
> 
> We created Ubuntu and Debian instances. According to Horizon, the 
> instance IPv6 is xxxx:xxxx:2f1:aaaa:f816:3eff:fe6d:c41a. Yet, we only 
> have a link local address which is fe80::f816:3eff:fe6d:c41a/64. TCPdump 
> indicates no Router Advertisement. We tried with and without adding a 
> router on the Network in Horizon. ICMPv6 is authorized in INGRESS from ::/0.
> 
> We checked on the controllers, the computes and in the Neutron 
> containers, systemctl indicated no instance of RADVD. Maybe we checked 
> incorrectly...
> 
> Do you have any suggestions ? I add that we are working with OpenStack 
> Ussuri deployed with OpenStack-ansible.
> 
> Thanks,
> Marc-Antoine
> 
> 
>> Le 8 mars 2022 à 08:59, Slawek Kaplonski <skaplons at redhat.com 
>> <mailto:skaplons at redhat.com>> a écrit :
>>
>> Hi,
>>
>> On poniedziałek, 7 marca 2022 10:36:30 CET Marc-Antoine Godde wrote:
>>> Hello,
>>>
>>> Thanks for your answer.
>>>
>>> If I’m correct, we can just use a virtual router with SLAAC since 
>>> RADVD can deal with RS and emit RA (with support for RFC6106), right ?
>>
>> Yes, virtual router created in the Neutron is enough there. It will 
>> spawn radvd in the qrouter namespace and will send RA to the Vms.
>> Please note that Neutron don't supports privacy extension [1] so You 
>> will need to make sure that it's disabled it on Your vms.
>>
>>> More generally, aren’t we suppose to have a virtual router every 
>>> time, even in DHCPv6 (stateless and statefull), to answer RS ? I have 
>>> to admit that I’m not very familiar at the moment with the 
>>> implementations of RFCs in OpenStack.
>>>
>>> Currently, we prefer the idea of adding IPv6 through SLAAC to have a 
>>> uniform network. If we do so, we’d like to avoid sending RA from our 
>>> physical router to limit its load. Yet, we do not any other arguments 
>>> to support this choice.
>>> Do you have any recommendations on what to do in latest versions of 
>>> OpenStack ? What is usually done ?
>>
>> TBH I don't have such experience. That's more question to operators of 
>> OpenStack.
>>
>>>
>>> Thanks,
>>> Marc-Antoine
>>>
>>>> Le 7 mars 2022 à 09:12, Slawek Kaplonski <skaplons at redhat.com 
>>>> <mailto:skaplons at redhat.com>> a écrit :
>>>>
>>>> Hi,
>>>>
>>>> On poniedziałek, 7 marca 2022 02:36:24 CET Marc-Antoine Godde wrote:
>>>>> Hello.
>>>>>
>>>>> We are progressively adding support for IPv6 in my company. We 
>>>>> decided to use SLAAC only for laptops, phones, … since DHCPv6 isn’t 
>>>>> supported on Android. RDNSS support will also increase. We are now 
>>>>> planning our deployment on OpenStack. We already know that we'll 
>>>>> rely only on neutron but we are not yet fixed between DHCPv6 and 
>>>>> SLAAC ? Do you have any arguments for one these for VMs ?
>>>>>
>>>>> Thanks,
>>>>> Marc-Antoine.
>>>>>
>>>>
>>>> With SLAAC You need to have Your network connected to the router in 
>>>> Neutron and You can only configure IP address on the VM. With DHCPv6 
>>>> You can configure other things, like some static-routes, etc.
>>>> Neutron supports DHCPv6 in the stateful and stateless variants. With 
>>>> stateless, You are using RA for address configuration and DHCP 
>>>> server for other configation. Please see [1] for more details.
>>>>
>>>> [1] 
>>>> https://docs.openstack.org/neutron/latest/admin/config-ipv6.html#address-modes-for-ports 
>>>> <https://docs.openstack.org/neutron/latest/admin/config-ipv6.html#address-modes-for-ports>
>>>>
>>>
>>>
>>
>> [1]https://datatracker.ietf.org/doc/html/rfc4941 
>> <https://datatracker.ietf.org/doc/html/rfc4941>
>>
>> --
>> Slawek Kaplonski
>> Principal Software Engineer
>> Red Hat
>