[ovs-discuss] QoS

Ben Pfaff blp at ovn.org
Sun May 15 04:59:19 UTC 2016


Have the controller detect congestion and, at that point, change the
flows and the configuration.

This is your goal, so it's now your job to implement it.  I doubt
whether others have implemented it already since, as I said, it doesn't
make sense in normal circumstances.

On Sat, May 14, 2016 at 09:53:50PM -0700, Aravind Ganesan wrote:
> Ben,
> Thanks for your reply.
> But how can apply it when the network is congested, and have regular flows
> when it is free.
> For example, if I want to check if bandwidth is less than x, at that point
> how to invoke QoS classes.
> Can you please help ?
> Thanks
> 
> On Sat, May 14, 2016 at 9:37 PM, Ben Pfaff <blp at ovn.org> wrote:
> 
> > You started out by saying that you created the QoS classes.  Just do
> > that from your controller.
> >
> > On Sat, May 14, 2016 at 04:01:35PM -0700, Aravind Ganesan wrote:
> > > Ben
> > > Thanks for your reply.
> > > I am able to measure statistics from pox controller, but I dont know how
> > to
> > > invoke the QoS classes when there is a congestion.
> > > Can you please help
> > > Thanks
> > >
> > > On Sat, May 14, 2016 at 3:26 PM, Ben Pfaff <blp at ovn.org> wrote:
> > >
> > > > You could write a controller that monitors link utilization and enables
> > > > QoS.
> > > >
> > > > On Sat, May 14, 2016 at 02:02:39PM -0700, Aravind Ganesan wrote:
> > > > > Ben
> > > > > Thanks for your reply.
> > > > > I am just worried about the case when the link is congested. if
> > possible,
> > > > > can you please describe how to do it in the controller
> > > > >
> > > > > Thanks
> > > > >
> > > > >
> > > > > On Sat, May 14, 2016 at 1:58 PM, Ben Pfaff <blp at ovn.org> wrote:
> > > > >
> > > > > > You could use a controller.
> > > > > >
> > > > > > You are probably wasting your effort, though, because the QoS in
> > use
> > > > > > probably does not do anything if the link is not congested.
> > > > > >
> > > > > > On Sat, May 14, 2016 at 12:22:21PM -0700, Aravind Ganesan wrote:
> > > > > > > Ben,
> > > > > > > Thanks for your reply.
> > > > > > > So is there a possible indirect method to achieve it?
> > > > > > > In my case too the QoS need not do anything when there is no
> > > > congestion,
> > > > > > > but I want to invoke them when there is congestion. I am able to
> > get
> > > > the
> > > > > > > network statistics, but am unable to proceed after that.
> > > > > > > It would be helpful if you could suggest something.
> > > > > > >
> > > > > > > Thanks
> > > > > > >
> > > > > > > On Sat, May 14, 2016 at 11:51 AM, Ben Pfaff <blp at ovn.org> wrote:
> > > > > > >
> > > > > > > > On Fri, May 13, 2016 at 11:19:19PM -0700, Aravind Ganesan
> > wrote:
> > > > > > > > > I have created QoS classes, and am able to separate the
> > traffic
> > > > > > based on
> > > > > > > > > source address.
> > > > > > > > > What I want to do now is enable QoS classes only when link is
> > > > > > congested.
> > > > > > > > > For example, if there are 3 hosts, h1, h2, h3, connected by
> > > > single
> > > > > > switch
> > > > > > > > > s1.  Suppose h1 is sending file to h3. Simultaneously h2
> > wants to
> > > > > > send
> > > > > > > > file
> > > > > > > > > to h3. I measure the bandwidth of s1->h3. If it is less than
> > say
> > > > 100
> > > > > > > > Mbps,
> > > > > > > > > I invoke QoS class and give priority to packets from h2.
> > > > > > > > > Is it possible to do this?
> > > > > > > >
> > > > > > > > OVS can't do that directly, but there's not much value in it
> > anyway
> > > > > > > > because most QoS strategies don't do anything if the link is
> > not
> > > > > > > > congested.
> > > > > > > >
> > > > > >
> > > >
> >



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