[ovs-discuss] I want to know how group table select works

[허지민]

Thank you for answering.

I'm not sure if I understood right.

The answer is saying that, if I don't change source or destination, bucket
selection won't be redone?

Well, I am using group table for my project, and each bucket in the group
has
different weight. When I tested group table, I found out that after long
term without networking, the selection has changed and send packets to
different bucket.

How does weight of the bucket influence the selection???

2016-08-02 2:10 GMT+09:00 Ben Pfaff <blp at ovn.org>:

> On Mon, Aug 01, 2016 at 05:39:10PM +0900, 허지민 wrote:
> > I am working on a project using group table select.
> >
> > I am figuring out how group table select one of the buckets that is added
> > in the group.
>
> This is in the FAQ.
>
> ### Q: How does OVS divide flows among buckets in an OpenFlow "select"
> group?
>
> A: In Open vSwitch 2.3 and earlier, Open vSwitch used the destination
>    Ethernet address to choose a bucket in a select group.
>
>    Open vSwitch 2.4 and later by default hashes the source and
>    destination Ethernet address, VLAN ID, Ethernet type, IPv4/v6
>    source and destination address and protocol, and for TCP and SCTP
>    only, the source and destination ports.  The hash is "symmetric",
>    meaning that exchanging source and destination addresses does not
>    change the bucket selection.
>
>    Select groups in Open vSwitch 2.4 and later can be configured to
>    use a different hash function, using a Netronome extension to the
>    OpenFlow 1.5+ group_mod message.  For more information, see
>    Documentation/group-selection-method-property.txt in the Open
>    vSwitch source tree.  (OpenFlow 1.5 support in Open vSwitch is still
>    experimental.)
>
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