[openstack-dev] Quantum L3 router, mixin or plugin?

Alan Kavanagh alan.kavanagh at ericsson.com
Fri Nov 9 22:43:47 UTC 2012


So I believe that's a very good point and one I firmly support, we should not enforce that issuing a Create_network implies you do an L-3 network and does not imply you tie this network to a router, fully agree we should avoid that as depending on the Virtual Networking Services you want to add that will then determine the need for other Networking Services such as a "Router".

Alan

From: Salvatore Orlando [mailto:sorlando at nicira.com]
Sent: November-09-12 9:27 AM
To: OpenStack Development Mailing List
Subject: Re: [openstack-dev] Quantum L3 router, mixin or plugin?

Replies inline.
On 9 November 2012 15:03, Ian Wells <ijw.ubuntu at cack.org.uk<mailto:ijw.ubuntu at cack.org.uk>> wrote:
On 9 November 2012 12:42, Bob Melander (bmelande) <bmelande at cisco.com<mailto:bmelande at cisco.com>> wrote:
Ok, I'm willing to work on this and I've created a blueprint to kick it off (https://blueprints.launchpad.net/quantum/+spec/quantum-l3-routing-plugin)

I too think VRRP (and some other features) would be nice to add. However, the first steps would be to take the inherited mixin and transform that into a plugin. That ought to be possible with fairly limited effort. Though there are some dependencies that need to be sorted out. In particular, core plugin methods like  create_network(...)make calls to mixin functions such as _process_l3_create(...), _extend_network_dict_l3(...), _process_l3_update(...):



self._process_l3_create(context, network['network'], net['id'])

...

self._extend_network_dict_l3(context, net)

One point here is that I would like to be able to create an unrouted network.  Creating a network *with* a router is a composite call (and in any case, shouldn't I be able to create a network and add a router later on?) and I don't think that functionality should be baked into create_network if we can avoid it.

That how we do it, actually.

1) POST /networks
Create a l2 network
2) POST /subnets with reference in body to previously created network
Defines a IP address range on the L2 network
3) POST /routers
Defined a l3 forwarding element
4) PUT /routers/<router-id>/add-router-interface
Connects a subnet to a router


I'm aware this breaks backward compatibility in the way I've described it, but just my 2c.  (Perhaps create_network becomes a thin wrapper over a more fundamental call, create_bare_network?)

The methods pointed out by Bob are not really for creating a router with a network; they are for managing the additions that the l3 API extensions makes to the "network" resource in order to handle "external" networks properly. I have more on then in my previous post.


There's reasons why you might want that: in a layered application, HA -> cache -> web appservers  -> DB for instance, most of the inner networks you might create for such a topology have no need of external routeability.  At the moment the rule seems to be 'if you don't need it, don't use it' but it would be nice to simply not have the router there in the first place.

Totally agree. Quantum v1 actually did not have any router and built multi-tier topologies as you describe them. The router is not necessary, and if you don't need it it does not get created.



--
Ian.

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