[ovs-dev] OVN architecture

Dave Tucker dave at socketplane.io
Mon Jan 19 14:32:02 UTC 2015


On 19 Jan 2015, at 13:04, Thomas Graf wrote:

> Agreed. I would expect that OVN might lead to more frequent releases
> of OVS with a more "stable at all times attitude" as OVN will depend 
> on
> specific OVS features.

This is my concern. For OVN to be useful in the context of OpenStack, we 
should bear in mind which OVS versions are out in the wild.
http://packages.ubuntu.com/search?suite=default&section=all&arch=any&keywords=openvswitch-switch&searchon=names

Looking at Ubuntu LTS releases for example - as it's hyped as most 
popular for OpenStack - we have:
	- OVS 1.4 in Ubuntu 12.04 (supported until 2018)
	- OVS 2.01 in Ubuntu 14.04 (supported until 201

Let's say, for the sake of discussion, that OVN will require ARP 
Responder and Conntrack - therefore OVS requirement is OVS 2.4+
So to deploy on Ubuntu, you have to compile/install an untested (by both 
OpenStack CI and distro) version of OVS :(

> Or we provide feature negotiation aside of versioning.

I'd love to see feature negotiation as backwards compatibility with OVS 
is top of my wishlist for OVN.
A rudimentary implementation could read the OVS version (if present) 
and/or schema version from OVSDB - we actually did this in OpenDaylight.

I'm biased, but I think the easiest option would be to use the OVS 
Python bindings.
The requirement on a system is "OVS w/ Python bindings + Python 
installed" and OVN could be installed using pip.

	e.g pip install openvswitch-ovn

Then again, OpenStack is only one use case and I've been out of the loop 
there for a while. Kyle's input would be appreciated here.



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