[ovs-discuss] SELECT groups - hash

Ben Pfaff blp at ovn.org
Sun Mar 25 00:47:53 UTC 2018


Here's an example usage:

ovs-ofctl -O OpenFlow15 add-group br0 'group_id=1234,type=select,selection_method=hash,fields(eth_dst,ip_dst,tcp_dst),bucket=output:10,bucket=output:11

On Sat, Mar 24, 2018 at 11:30:12PM +0100, Slavica Tomovic wrote:
> Thank Ben.
> 
> Can you help me with the syntax? I tried this:
> 
> ovs-ofctl  mod-group s11 group_id=24, type=select, selection_method=hash
> 
> However, I am getting an error the mod-group command takes at most two
> arguments.
> I am using OVS 2.5.2.
> 
> Also, how should I specify the fields? In the documentation, I found this:
> 
> fields(field[=mask]...)
> 
> Does this mean that I should specify the fields like this:
> fields(nw_src nw_dst udp..)?
> 
> 
> Thanks in advance,
> Slavica
> 
> 2018-03-24 19:10 GMT+01:00 Ben Pfaff <blp at ovn.org>:
> 
> > On Sat, Mar 24, 2018 at 06:45:50PM +0100, Slavica Tomovic wrote:
> > >  Hi,
> > >
> > > I am using SELECT Group tables for load balancing purposes in OpenFlow
> > > network. However, I found that OVS by default performs hashing only on IP
> > > addresses, MAC addresses, VLAN IDs, TCP ports and EthType fields. Is it
> > > possible to change this and use a hash function that depends on UDP port?
> > >
> > > I have read these posts:
> > > https://mail.openvswitch.org/pipermail/ovs-discuss/2016-July/041934.html
> > > https://mail.openvswitch.org/pipermail/ovs-dev/2015-March/214529.html
> > >
> > > and according to them I need to do this by implementing a logic for
> > > creation of group properties structure on SDN controller. Can I avoid
> > this
> > > somehow and configure OVS switches with some command to perform hashing
> > on
> > > UDP ports?
> >
> > It sounds like you just need to use ovs-ofctl to configure the behavior
> > you want.  Did you read the "Group Syntax" section in the manpage?  You
> > want to specify the "fields" parameter.
> >


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