Hi Uwe,
On Thu, 19 Sep 2019 at 11:36, Uwe Kleine-König
<u.kleine-koe...@pengutronix.de> wrote:
>
> On Thu, Sep 19, 2019 at 10:00:51AM +0200, Sascha Hauer wrote:
> > Hi Vladimir,
> >
> > On Wed, Sep 18, 2019 at 05:36:08PM +0300, Vladimir Oltean wrote:
> > > Hi Sascha,
> > >
> > > On Wed, 18 Sep 2019 at 17:03, Sascha Hauer <s.ha...@pengutronix.de> wrote:
> > > >
> > > > Hi All,
> > > >
> > > > We have a customer using a Marvell 88e6240 switch with Ethercat on one
> > > > port and
> > > > regular network traffic on another port. The customer wants to
> > > > configure two things
> > > > on the switch: First Ethercat traffic shall be priorized over other
> > > > network traffic
> > > > (effectively prioritizing traffic based on port). Second the ethernet
> > > > controller
> > > > in the CPU is not able to handle full bandwidth traffic, so the traffic
> > > > to the CPU
> > > > port shall be rate limited.
> > > >
> > >
> > > You probably already know this, but egress shaping will not drop
> > > frames, just let them accumulate in the egress queue until something
> > > else happens (e.g. queue occupancy threshold triggers pause frames, or
> > > tail dropping is enabled, etc). Is this what you want?
> >
> > If I understand correctly then the switch has multiple output queues per
> > port. The Ethercat traffic will go to a higher priority queue and on
> > congestion on other queues, frames designated for that queue will be
> > dropped. I just talked to our customer and he verified that their
> > Ethercat traffic still goes through even when the ports with the general
> > traffic are jammed with packets. So yes, I think this is what I want.
>
> Moreover egressing the cpu port has the advantage that network
> participants on other ports that might be able to process packet quicker
> are not limited.
>
Yes, that is true if you apply port-based policers (matchall), but not
necessarily so if your switch is able to do ingress classification (a
common key for switches being the {DMAC, VLAN} pair). Again, there is
a model for configuring even that, if the hardware is capable. Just
not for egress shaping on the CPU port.
> Best regards
> Uwe
>
> --
> Pengutronix e.K. | Uwe Kleine-König |
> Industrial Linux Solutions | http://www.pengutronix.de/ |
