On Fri, Apr 11, 2025 at 02:11:20PM +0200, Adrián Moreno wrote:
> On Thu, Apr 10, 2025 at 12:10:13PM +0100, brendan.do...@oracle.com wrote:
> > Hi Dumitru/Adrian,
> >
> >
> >
> > I'm working my way through IPFIX test in system-ovn.at, just a couple of
> > questions.
> >
> > > collector1=$(ovn-nbctl create Sample_Collector id=1 name=c1
> > > probability=65535 set_id=100)
> > > collector2=$(ovn-nbctl create Sample_Collector id=2 name=c2
> > > probability=65535 set_id=200)
> > > check_row_count nb:Sample_Collector 2
> > >
> > > check_uuid ovn-nbctl create Sampling_App type="acl-new" id="42"
> > > check_uuid ovn-nbctl create Sampling_App type="acl-est" id="43"
> > > check_row_count nb:Sampling_App 2
> > >
> > > dnl Create ACLs that match the 3 types of traffic in all 3 possible
> > > stages:
> > > dnl from-lport, from-lport-after-lb, to-lport.
> > > check_uuid ovn-nbctl \
> > > -- --id=@sample_in_1c_new create Sample collector="$collector1"
> > > metadata=1001 \
> > I don't follow this syntax, it is not described in the ovn-nbctl man page,
> > there we just
> > have
> > ovn-nbctl --sample-new=<uuid of a row of the Sample table> acl-add
> >
> > So what is 'id' above?
> >
> > what is '@sample_in_1c_new' is it "42"?
>
> All OVS and OVN commands that interact with an OVSDB (such as ovn-nbctl
> or ovs-vsctl), apart from some specific "high level" commands,
> (such as "acl-add [---sample-new]..."), support interacting with the OVSDB
> directly,
>
> See "Database Commands" section in ovn-nbctl(8).
>
> This part of the command is creating an entry in the Sample action and
> _storing_ its id in a temporary reference called "sample_in_1c_new"
> which can be used in the same OVSDB transaction futher below.
>
> >
> > Is it required to also specify 'create Sample collector', it is not
> > described in the ovn-nbctl man page.
> >
>
> From manpage:
>
> ovn-nbctl [--id=(@name|uuid)] create table column[:key]=value...
>
>
> > Is '$collector1' the UUID of the Sample_Collector table row we created with
> > set_id=100 ?
> >
>
> Yes
>
> > What is 'metadata' - Is it arbitrary?
> >
>
> Since the command is editing the DB directly, you should look at the
> ovn-nb(5) for the documentation of each column in the table. Quoting
> such manpage:
>
> """
> metadata: integer, in range 1 to 4,294,967,295 (must be unique within table)
>
> Will be used as Observation Point ID in every sample. The Observation
> Domain ID will be generated by ovn-northd and includes the logical datapath
> key as the least significant 24 bits and the sampling application type (e.g.,
> drop debugging) as the 8 most significant bits.
> """
>
> > Also I see in the ovn-nbctl man page, we have --sample-new and --sample-est,
> > but no
> > --sample-drop, even though the ovn-nb man pages says the 'type' in the
> > Sampling_App
> > Table can be acl-est, acl-new, or drop
> >
>
> You are right. "--sample-{new,est}" are options to "acl-add". If you
> enable those options, _only_ ACL drops will be sampled.
>
> In order to sample _all_ drops (including implicit ones), we used to
> have two flags in NB_Global:options but those got superceeded by just
> configuring the Sampling_App table. Nevertheless, this was not added as
> a "high level" command to ovn-nbctl. Global options tend not to be, plus
> this is a debugging-oriented feature.
>
> Thanks.
> Adrián
>
It seems my email client tricked me and did not that Dumitru has already
answered! :-) Please ignore as his answer is more complete.
Adrián
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