[ovs-dev] [PATCH v1 1/4] ovn: l3ha, handling of multiple gateways

[Miguel Angel Ajo Pelayo]

Hi Liran,

For now we're focusing on Active/Backup implementation,

A very brief introduction to the active/active problem can be found
here [1].

I'm not an expert on this area and I haven't investigated yet.
I'd guess we could have several options, like:

* handling it at L3 level (ECMP),

Or

* handling it at L2 level (I guess that's what you propose), a naive
understanding takes me to some complexities:
   - balancing traffic across the gateways, we can do that in openflow
     (bundle/multipath actions?)
   - announcing (ARP) in a way that any Active gateway could
     handle incoming traffic (similar to link aggregation), but that's
     also complex because we may need to keep connection tracking in
     sync across gateways.

Again, I'm not an expert on this area, but if we gave good ideas
it'd be great to document them around [1]

Best regards,
Miguel Ángel Ajo


[1]
https://github.com/openvswitch/ovs/blob/master/Documentation/topics/high-availability.rst#fully-active-active-ha

On Mon, Jun 5, 2017 at 1:20 PM, Liran Schour <LIRANS at il.ibm.com> wrote:

> ovs-dev-bounces at openvswitch.org wrote on 02/06/2017 03:31:41 PM:
>
> > From: Miguel Angel Ajo <majopela at redhat.com>
> >
> > This patch handles multiple gateways with priorities in chassisredirect
> > ports, any gateway with a chassis redirect port will implement the
> > rules to de-encapsulate incomming packets for such port.
> >
> > And hosts targetting a remote chassisredirect port will setup a
> > bundle(active_backup, ..) action to each tunnel port, in the given
> > priority order.
> >
>
> Hi Miguel,
>
> I was looking on your recent pathces on OVN L3HA (not a deep review ;-)
>  and a question came to my mind, maybe you will be able to answer :-)
>
> In case of a full active-active solution. Why not to use the load
> balancing built in feature of OVS to distribute traffic between gateways?
> Maybe I miss something here...
>
> Thanks,
> - Liran
>