[Openstack] Quantum question
gabriel_staicu at yahoo.com
Sat Jul 13 23:21:34 UTC 2013
With the second question I think you touched the right spot.
I will try to clarify using an example. Let's imagine the following situation:
You have to deploy openstack in an environment where you don't have any type of the control of the network side. I am referring here to the control on the routers, switches, firewall. You are just a consumer of an IP space which is administered by the network department. You can just plug physical cable in the switch they tell you and by means of the dhcp they will provide you with all the information for your physical servers and also for the virtual ones. In this case the openstack model you can use is: flat_network (the one you specified in your first message). The openstack framework will just create for you a virtual bridge (a L2 segment) which will be connected by the physical network card of the host to the physical network in your enterprise. The virtual machines will receive IP addresses from an DHCP server that you do not control. So your virtual machines will have IP addresses from the enterprise space, and will be accessible directly from
inside like any other machine without NAT. From the openstack perspective will be just a forwarding at L2 level. This is flat network.
In the above example let's suppose that you can negotiate with the network department to reserve you a subspace of the enterprise space: a continuous ip addresses range that they won't allocate from their DHCP server. In this case you can use in openstack flat_dhcp option. The openstack framework will use dnsmasq to simulate dhcp service. This means that openstack will simulate a virtual bridge but in plus of the above situation in this virtual switch it will plug virtually also a dhcp service that you will manage and which it will provide ip addresses to your virtual machines. From here it is exactly like the first case.
So to answer to your question you can not do a port mapping on the physical router because you do not have access to that equipment. All you administer in those to cases is the openstack environment and on it from the networking point of view you just have a virtual switch in the first case, a virtual switch and a dhcp in the second one and there is no place to do NAT so no floating in those 2 cases.
Spero che sia piu chiaro adesso .. :),
From: Remo Mattei <remo at mattei.org>
To: Staicu Gabriel <gabriel_staicu at yahoo.com>
Cc: "openstack at lists.launchpad.net" <openstack at lists.launchpad.net>
Sent: Sunday, July 14, 2013 1:48 AM
Subject: Re: [Openstack] Quantum question
One more thing to this slide there is a physical router that can be configured by the admin etc and I can do a port mapping from there so why the floating will not be an option? Not clear again.
Inviato da iPad ()
Il giorno Jul 13, 2013, alle ore 15:26, Remo Mattei <remo at mattei.org> ha scritto:
So if I add a virtual router I will have this working the models are not well describe why and that is a problem not only to me but others as well when to choose which one etc.
>Inviato da iPad ()
>Il giorno Jul 13, 2013, alle ore 13:44, Staicu Gabriel <gabriel_staicu at yahoo.com> ha scritto:
>>If your talking about this document: http://docs.openstack.org/grizzly/openstack-network/admin/content/use_cases_single_flat.html I think that in that case you don't have something from the logical point of view something like a router. You just have L2 segments so there is no place where NAT can happen and therefore you can not use floating ip notion.
>>In floating ip case practically the framework creates a static NAT between the floating ip and the private ip that the instance receive when boots up.
>> From: Remo Mattei <remo at mattei.org>
>>To: openstack at lists.launchpad.net
>>Sent: Saturday, July 13, 2013 11:23 PM
>>Subject: [Openstack] Quantum question
>>Hello everyone I was reading the doc and it was saying that model one on quantum does not support floating ip address and I wonder why this limitation
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