On Wed, Mar 29, 2017 at 11:25 AM, Ben Pfaff <[email protected]> wrote: > On Wed, Mar 29, 2017 at 10:25:31AM -0700, Andy Zhou wrote: >> On Fri, Mar 17, 2017 at 8:16 AM, Ben Pfaff <[email protected]> wrote: >> > Signed-off-by: Ben Pfaff <[email protected]> >> > --- >> > Documentation/faq/openflow.rst | 8 ++++++++ >> > 1 file changed, 8 insertions(+) >> > >> > diff --git a/Documentation/faq/openflow.rst >> > b/Documentation/faq/openflow.rst >> > index 376e64eb4482..214e38e6a9aa 100644 >> > --- a/Documentation/faq/openflow.rst >> > +++ b/Documentation/faq/openflow.rst >> > @@ -462,6 +462,14 @@ What's going on? >> > messages and will send an error response if any other value of this >> > field >> > is included in a "packet-out" or a "flow mod" sent by a controller. >> > >> > + Packet buffers have limited usefulness in any case. Table-miss >> > packet-in >> > + messages most commonly pass the first packet in a microflow to the >> > OpenFlow >> > + controller, which then sets up an OpenFlow flow that handles remaining >> > + traffic in the microflow without further controller intervention. In >> > such >> > + a case, the packet that initiates the microflow is usually small, >> > which >> > + means that the switch sends the entire packet to the controller and >> > the >> > + buffer only saves a small number of bytes in the reverse direction. >> > + >> I can see that In case of TCP, the packet buffer is usually small >> (except DOS). But >> it is not clear to me that why this is true in general. May be you >> mean this is what we >> have observed in practice? > > Yes. > > Here's a version that is slightly reworded: > > --8<--------------------------cut here-------------------------->8-- > > From: Ben Pfaff <[email protected]> > Date: Wed, 29 Mar 2017 11:25:38 -0700 > Subject: [PATCH] faq: Expand on answer about packet buffering removal. > > Signed-off-by: Ben Pfaff <[email protected]> > --- > Documentation/faq/openflow.rst | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/Documentation/faq/openflow.rst b/Documentation/faq/openflow.rst > index 376e64eb4482..d21bb4459395 100644 > --- a/Documentation/faq/openflow.rst > +++ b/Documentation/faq/openflow.rst > @@ -462,6 +462,15 @@ What's going on? > messages and will send an error response if any other value of this field > is included in a "packet-out" or a "flow mod" sent by a controller. > > + Packet buffers have limited usefulness in any case. Table-miss packet-in > + messages most commonly pass the first packet in a microflow to the > OpenFlow > + controller, which then sets up an OpenFlow flow that handles remaining > + traffic in the microflow without further controller intervention. In > such > + a case, the packet that initiates the microflow is in practice usually > + small (certainly for TCP), which means that the switch sends the entire > + packet to the controller and the buffer only saves a small number of > bytes > + in the reverse direction. > + > 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 > -- > 2.10.2 >
Thanks for the revision. Acked-by: Andy Zhou <[email protected]> _______________________________________________ dev mailing list [email protected] https://mail.openvswitch.org/mailman/listinfo/ovs-dev
