Open Stack

On May 22, 2017 9:34 AM, "Chris Marino" <chris at romana.io> wrote:

I'm digging into how Routed Provider Networks work and have some questions
as well. I will presenting at the OpenStack Meetup
<https://www.meetup.com/openstack/events/239889735/>on Wed on this and want
to make sure I have my facts straight......

>From the doc page
<https://docs.openstack.org/ocata/networking-guide/config-routed-networks.html>
it
shows a multi-segment network with segment 1 on 203.0.113.0/24 and segment
2 on 198.51.100.0/24. It also suggests using the same VLAN ID for these
segments.

I find both of these things really confusing.


What do you find confusing about this? It's a pretty standard L3 to ToR and
L2 in rack setup. L2 is limited to the rack so you can use or not use
whatever VLANs in that scope. We can fix the docs to clear up whatever
confusion you have.

But ignoring that for a minute, I'm more interested in the expected use
case for this feature. I see from the original spec/blueprint
<http://specs.openstack.org/openstack/neutron-specs/specs/newton/routed-networks.html>
that the
goal was to allow for a single Provider Network to be made up from multiple
network segments, where external routing provided connectivity among the
segments. And Routed Provider Networks provide this.  Great.

But the use cases I'm curious about are where the operator wants to take
their current L2/VLAN Provider Networks, but deploy it as an L3 Provider
Network. Same CIDR as the L2 provider network, but in a fully routed
deployment (i.e. no L2 adjacency). It might be L3 to the ToR and (untagged)
L2 to the host. Or L3 to the host.

Both of these configurations are gaining popularity and wondering how they
would need to be configured. For the L3 to ToR, the network segments would
have to be split across the ToRs as described in the doc, but what about L3
to host? Guessing a segment per host, but wondering how practical that's
going to be without better coordination of IP/segments with Nova?


L3 to the host and one segment per host is possible, but it's going to have
a severe limitation of not being able to migrate VMs without an IP change.
To get migration at that point you will need some form of dynamic routing.

L3 to ToR and L2 in rack is definitely the target use case as of now.

On May 22, 2017 9:34 AM, "Chris Marino" <chris at romana.io> wrote:

> I'm digging into how Routed Provider Networks work and have some questions
> as well. I will presenting at the OpenStack Meetup
> <https://www.meetup.com/openstack/events/239889735/>on Wed on this and
> want to make sure I have my facts straight......
>
> From the doc page
> <https://docs.openstack.org/ocata/networking-guide/config-routed-networks.html> it
> shows a multi-segment network with segment 1 on 203.0.113.0/24 and
> segment 2 on 198.51.100.0/24. It also suggests using the same VLAN ID for
> these segments.
>
> I find both of these things really confusing. But ignoring that for a
> minute, I'm more interested in the expected use case for this feature. I
> see from the original spec/blueprint
> <http://specs.openstack.org/openstack/neutron-specs/specs/newton/routed-networks.html> that the
> goal was to allow for a single Provider Network to be made up from multiple
> network segments, where external routing provided connectivity among the
> segments. And Routed Provider Networks provide this.  Great.
>
> But the use cases I'm curious about are where the operator wants to take
> their current L2/VLAN Provider Networks, but deploy it as an L3 Provider
> Network. Same CIDR as the L2 provider network, but in a fully routed
> deployment (i.e. no L2 adjacency). It might be L3 to the ToR and (untagged)
> L2 to the host. Or L3 to the host.
>
> Both of these configurations are gaining popularity and wondering how they
> would need to be configured. For the L3 to ToR, the network segments would
> have to be split across the ToRs as described in the doc, but what about L3
> to host? Guessing a segment per host, but wondering how practical that's
> going to be without better coordination of IP/segments with Nova?
>
> CM
> ᐧ
>
> On Sun, May 21, 2017 at 6:12 AM, Alex Evonosky <alex.evonosky at gmail.com>
> wrote:
>
>> Thank you Yura.
>>
>> A
>>
>> On Thu, May 18, 2017 at 3:24 AM, Yura Poltoratskiy <yurapoltora at gmail.com
>> > wrote:
>>
>>> Hi
>>>
>>> On 17.05.2017 21:56, Alex Evonosky wrote:
>>>
>>>> Hello fellow Openstackers-
>>>>
>>>> I have a quick question regarding routed provider networks.  I am
>>>> looking at this
>>>> page: https://docs.openstack.org/ocata/networking-guide/config-rou
>>>> ted-networks.html
>>>>
>>>> I configured the controller as stated in the docs, however this line is
>>>> somewhat vaugue:
>>>>
>>>> "
>>>>
>>>>
>>>>       Network or compute nodes¶
>>>>       <https://docs.openstack.org/ocata/networking-guide/config-ro
>>>> uted-networks.html#network-or-compute-nodes>
>>>>
>>>>   * Configure the layer-2 agent on each node to map one or more segments
>>>>     to the appropriate physical network bridge or interface and restart
>>>>     the agent."
>>>>
>>>>
>>>> Which file am I editing on the compute nodes to answer the above
>>>> question?
>>>>
>>> If you are using OpenVSwitch agent, then on compute/network node you
>>> should modify:
>>> /etc/neutron/plugins/ml2/openvswitch_agent.ini
>>> /etc/neutron/plugins/ml2/ml2_conf.ini
>>>
>>>
>>>>
>>>> Thank you,
>>>> A
>>>>
>>>>
>>>> _______________________________________________
>>>> Mailing list: http://lists.openstack.org/cgi
>>>> -bin/mailman/listinfo/openstack
>>>> Post to     : openstack at lists.openstack.org
>>>> Unsubscribe : http://lists.openstack.org/cgi
>>>> -bin/mailman/listinfo/openstack
>>>>
>>>>
>>> _______________________________________________
>>> Mailing list: http://lists.openstack.org/cgi
>>> -bin/mailman/listinfo/openstack
>>> Post to     : openstack at lists.openstack.org
>>> Unsubscribe : http://lists.openstack.org/cgi
>>> -bin/mailman/listinfo/openstack
>>>
>>
>>
>> _______________________________________________
>> Mailing list: http://lists.openstack.org/cgi
>> -bin/mailman/listinfo/openstack
>> Post to     : openstack at lists.openstack.org
>> Unsubscribe : http://lists.openstack.org/cgi
>> -bin/mailman/listinfo/openstack
>>
>>
>
> _______________________________________________
> Mailing list: http://lists.openstack.org/cgi-bin/mailman/listinfo/
> openstack
> Post to     : openstack at lists.openstack.org
> Unsubscribe : http://lists.openstack.org/cgi-bin/mailman/listinfo/
> openstack
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.openstack.org/pipermail/openstack/attachments/20170523/aad6a549/attachment.html>