On Tue, Nov 15, 2016 at 01:30:34AM -0800, Ben Pfaff wrote:
> On Tue, Nov 15, 2016 at 05:45:06AM +0000, Daniel Ye wrote:
> > As we know, NXAST_RAW_SAMPLE2 was introduced to OVS to make flow-based
> > IPFIX to support tunnel information exporting. A field called
> > “sampling_port” is added in NXAST_RAW_SAMPLE2 and it’s an
> > ofp-port. This field is not only used for exporting tunnel
> > information, but also used for judging the flow direction.
> >
> > However, recently I found NXAST_RAW_SAMPLE2 cannot be used for patch
> > port, because there is no odp-port for a patch port. The conversion
> > between NXAST_RAW_SAMPLE2 and datapath sample action will fail. The
> > simple solution about this problem is that we can use NXAST_RAW_SAMPLE
> > openflow action instead of NXAST_RAW_SAMPLE2. But the limitation is
> > that NXAST_RAW_SAMPLE action didn’t have a field to imply the flow
> > direction. According to our discuss, a better solution is that adding
> > NXAST_RAW_SAMPLE3, which have a direction field to show the flow
> > direction. This sample action will looks like sample(…, ingress|
> > egress).
>
> Yes, all of this matches what we talked about earlier today. It should
> be easy to add support for "ingress" and "egress" keywords on the sample
> action. It looks like NXAST_RAW_SAMPLE2 was planned well enough that we
> don't even need to introduce a NXAST_RAW_SAMPLE3. That part should be
> simple and straightforward.
>
> I started looking through the code to see what is needed. The part that
> I do not understand yet is what should happen differently when one of
> these keywords is specified. For the case where a tunnel port is
> specified, the code retrieves information related to tunneling and puts
> that into the IPFIX report. But I haven't noticed, yet, what the sample
> action should report differently over IPFIX if it knows that it is an
> ingress or egress but it does not have tunnel information.
>
> Actually, looking closer, I guess that there is this code in
> ipfix_cache_entry_init() which adds to the IPFIX report whether the
> packet is sampled on ingress or egress:
>
> data_common->flow_direction =
> (output_odp_port == ODPP_NONE) ? INGRESS_FLOW : EGRESS_FLOW;
>
> Is that all that should change in the IPFIX report based on this
> keyword? If so, then I think that this should be really simple to
> implement. In that case, I'm willing to propose a patch myself, if you
> would like that.
I posted a patch:
https://patchwork.ozlabs.org/patch/698546/
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