[ovs-discuss] OpenFlow “select” group

Ben Pfaff blp at ovn.org
Mon Nov 20 17:37:40 UTC 2017


On Thu, Nov 16, 2017 at 04:41:07PM -0500, Ronaldo Resende wrote:
> I know that Open vSwitch 2.4 and later + OpenFlow 1.4, by default, hashes
> some headers fields to choose a bucket in a select group.
> 
> What if I want to change the way this is being done? What would be the
> right approach to accomplish this? (i.e distribute packets among buckets
> using some king of counter, to create an evenly load balance).
> 
> Which codes should I considering poking around?

You would need to start by figuring out how to implement this at the
datapath level, that is, in the Linux kernel module.  The datapath
doesn't currently have any concept that can be used to serialize
packets.  (Serializing packets will slow things down because it
inherently prevents parallelism, but maybe you don't care about
performance?)  Maybe you could add some kind of datapath action to
increment a counter and store it in dp_hash and then recirculate,
analogous to the way that there's an action to hash fields and
recirculate.


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