[ovs-discuss] Implementing 'group type select' algo in the switch

Ben Pfaff blp at nicira.com
Fri Jun 12 15:50:28 UTC 2015


Make sure you're using OVS from master.

On Fri, Jun 12, 2015 at 08:24:27PM +0500, Haleema Sadia wrote:
> Yes I tried it with -O OpenFlow15 but it said the same.
> 
> Sorry I missed the switch name in the previous command.
> ovs-ofctl -O OpenFlow15 add-group
> s1 group_id=1,type=select,selection_method=hash,bucket=output:2,bucket=output:3
> 
> On Friday, June 12, 2015, Ben Pfaff <blp at nicira.com> wrote:
> 
> > Try this (note that configuring the selection method only works with the
> > experimental OpenFlow 1.5 protocol):
> >
> > utilities/ovs-ofctl -O OpenFlow15 add-group br0
> > group_id=1,type=select,selection_method=hash,bucket=output:2,bucket=output:3
> >
> > On Fri, Jun 12, 2015 at 08:20:48PM +0500, Haleema Sadia wrote:
> > > Ovs-ofctl add-group group_id=1,
> > > type=select,selection_method=hash,bucket=output:2,bucket=output:3 -O
> > > OpenFlow13
> > >
> > > On Friday, June 12, 2015, Ben Pfaff <blp at nicira.com <javascript:;>>
> > wrote:
> > >
> > > > Can you provide the entire ovs-ofctl command?
> > > >
> > > > On Fri, Jun 12, 2015 at 08:15:52PM +0500, Haleema Sadia wrote:
> > > > > Yes, tested it with more flows a while ago and it was working fine! I
> > > > tried
> > > > > giving selection_method=hash with the group type select. Ovs-ofctl
> > > > telling
> > > > > me unknown keyword. Why is that?
> > > > >
> > > > > On Friday, June 12, 2015, Ben Pfaff <blp at nicira.com <javascript:;>
> > <javascript:;>>
> > > > wrote:
> > > > >
> > > > > > It's a hash, so it's probabilistic.  You'll only get a
> > statistically
> > > > > > even distribution if you have a large number of flows.  For two
> > flows,
> > > > > > there is a 50% chance they end up in the same bucket.
> > > > > >
> > > > > > On Fri, Jun 12, 2015 at 03:30:37PM +0500, Haleema Sadia wrote:
> > > > > > > My topology is two hosts connected to a switch and I am sending
> > two
> > > > flows
> > > > > > > from host 1 to host 2. What I want to do is use the select group
> > type
> > > > > > with
> > > > > > > two different buckets. But both of my flows are being mapped to
> > one
> > > > > > bucket,
> > > > > > > essentially. Shouldn't the select function, which is taking a
> > hash of
> > > > > > > src/dst ports and ips, map each blow to different bucket?
> > > > > > >
> > > > > > >
> > > > > > >
> > > > > > > On Fri, Jun 12, 2015 at 3:20 AM, Ben Pfaff <blp at nicira.com
> > <javascript:;>
> > > > <javascript:;>
> > > > > > <javascript:;>> wrote:
> > > > > > >
> > > > > > > > The default is a hash (not just an xor) over fields up to L4,
> > but
> > > > you
> > > > > > > > can configure another method using the extensions implemented
> > by
> > > > > > > > Netronome.
> > > > > > > >
> > > > > > > > On Thu, Jun 11, 2015 at 11:07:56PM +0500, Haleema Sadia wrote:
> > > > > > > > > What is the current ovs version using for select type? As
> > far as
> > > > I
> > > > > > could
> > > > > > > > > understand it is taking a xor of src and destination
> > addresses
> > > > and
> > > > > > tcp
> > > > > > > > > ports? Is it correct?
> > > > > > > > >
> > > > > > > > > On Thursday, June 11, 2015, Ben Pfaff <blp at nicira.com
> > <javascript:;>
> > > > <javascript:;> <javascript:;>>
> > > > > > wrote:
> > > > > > > > >
> > > > > > > > > > On Thu, Jun 11, 2015 at 01:13:22PM +0500, Haleema Sadia
> > wrote:
> > > > > > > > > > > I was wondering if you could help me figuring out where
> > the
> > > > > > > > algorithm for
> > > > > > > > > > > the group type "select" is implemented in ovs switch
> > files? I
> > > > > > want to
> > > > > > > > > > > implement a function which takes the hash of the src/dst
> > ip,
> > > > and
> > > > > > > > src/dst
> > > > > > > > > > > port and selects the corresponding bucket for the packet.
> > > > > > > > > >
> > > > > > > > > > xlate_select_group() in ofproto-dpif-xlate.c
> > > > > > > > > >
> > > > > > > >
> > > > > >
> > > >
> >



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