[ovs-dev] [RFC] Proposal for enhanced select groups

[Ben Pfaff]

On Wed, Aug 27, 2014 at 10:26:14AM +0900, Simon Horman wrote:
> On Fri, Aug 22, 2014 at 08:30:08AM -0700, Ben Pfaff wrote:
> > On Fri, Aug 22, 2014 at 09:19:41PM +0900, Simon Horman wrote:
> > > I have been working with Netronome on examining the possibilities of
> > > providing (richer) load balancing facilities in Open vSwitch.
> > > 
> > > It seems to us that the current select group provides for some load
> > > balancing functionality. And that in particular the way that it is
> > > implemented in Open vSwitch provides L2 destination load balancing (it
> > > hashes on the destination ethernet address). Our ideas so fare are as follows:
> > > 
> > > 1. Provide a richer and ideally extendible select group in the
> > >    form of an OpenFlow extension to groups.
> > > 
> > >    * Allow the fields used to be selected.
> > > 
> > >      In the case of a hash this would be the fields that are hashed.
> > > 
> > >      An implication of this is that the pre-requisites of these
> > >      fields would need to be present in the flow's match.
> > >      In masking of the fields would be allowed but not
> > >      required for fields whose TLVs allow masking.
> > > 
> > >    * Allow designation of the selection method used.
> > > 
> > >      For example hash.
> > > 
> > >    * Allow passing a parameter to the selection method.
> > > 
> > >      For example an initial value key for hashes.
> > 
> > There is an outstanding patch on this topic already:
> >         http://patchwork.openvswitch.org/patch/5424/
> 
> I have no particular objections to that change, though I have
> not thought about it deeply. However, I think its more valuable
> in the long run to make select groups configurable rather than
> tweaking what would be the default setting.
> 
> > It sounds reasonable to make select groups configurable.  The way to do
> > that would be to implement the OpenFlow 1.5 (draft) proposal to add
> > properties to groups and group buckets, which is filed in the ONF JIRA
> > as EXT-350.
> 
> I'm happy to look at implementing EXT-350 (which I now have access to :)
> however it seems to me that while it makes groups more configurable
> it does not address the ability to configure the selection method.

Why not?  Part of the configuration can be the selection method.

> What we would like to do is to provide something generally useful
> which may be used as appropriate to:

I'm going to skip past these ideas, which do sound interesting, because
I think that they're more for Pravin and Jesse than for me.  I hope that
they will provide some reactions to them.

> ----------------------------------------------------------------------
> Proposal: Proposal for enhanced select groups
> Version: 0.0.1

The proposal seems reasonable on its own but given that EXT-350 allows a
standardized way to add group configuration extension I am not sure it
makes sense to add a specialized way to do that.