[ovs-dev] Query regarding OF1.5 Egress tables (EXT-306)

niti Rohilla niti1489 at gmail.com
Wed Aug 19 07:48:37 UTC 2015


Thanks Jean.

>Capabilities are not modified by the ofp_table_mod messages,
>either the implementation is capable, or it is not, and this does not
>dynamically change. Don't confuse with the 'config' field in
>ofp_table_desc that describe if the feature is enabled or not.
>Note that this is one of the most subtle change from 1.3 to
>1.4.

With reference to DESIGN.md - OFPTC_* Table Configuration

"OFPT_TABLE_MOD still controlled these settings.  The field for OFPTC_*
values in OFPMP_TABLE_FEATURES was renamed from 'config' to
'capabilities' and documented as reporting the flags that are
supported in a OFPT_TABLE_MOD message.  The OFPMP_TABLE_DESC message
newly added in OF1.4 reported the OFPTC_* setting."

So as per our understanding, 'config' is renamed to 'capabilities' in
'OFPMP_TABLE_FEATURES'. Also, OFPT_TABLE_MOD can be used to configure table
'config' properties, OFPMP_TABLE_DESC is used to report OFPTC_* settings
and OFPMP_TABLE_FEATURES is used to report the flags supported in
OFPT_TABLE_MOD messages.

Also when these OFPTC_* flags are modified using table_mod messages we need
to pass ofp_table_mod_prop_eviction and
ofp_table_mod_prop_vacancy properties along with the messages. So how can
we modify capabilities/config(OFPTC_*) using OFPTFC_MODIFY command?

Kindly suggest if we are missing something regarding OFPTFC_MODIFY command.

Thanks & Regards
Niti Rohilla

On Tue, Aug 18, 2015 at 9:41 PM, Jean Tourrilhes <jt at hpl.hp.com> wrote:

> On Tue, Aug 18, 2015 at 05:40:34PM +0530, niti Rohilla wrote:
> > Hi Jean,
> >
> > Thanks for your reply. Based on your reply please validate our
> > understanding.
> >
> > 1. From all the commands only OFPTFC_MODIFY needs to be implemented and
> > only for a single table in a request. This command is used to modify flow
> > table capabilities and will not modify pipeline processing or any other
> > ofp_table_features parameter.
>
>         That's what I would do.
>
> > So what is the significance of implementing OFPTFC_MODIFY command as the
> > capabilities (OFPTC_EVICTION, OFPTC_VACANCY_EVENTS) can be modified using
> > ofp_table_mod messages. When these OFPTC_* flags are modified using
> > table_mod messages we need to pass ofp_table_mod_prop_eviction and
> > ofp_table_mod_prop_vacancy properties along with the messages. So how can
> > we implement capabilities using OFPTFC_MODIFY command?
>
>         Capabilities are not modified by the ofp_table_mod messages,
> either the implementation is capable, or it is not, and this does not
> dynamically change. Don't confuse with the 'config' field in
> ofp_table_desc that describe if the feature is enabled or not.
>         Note that this is one of the most subtle change from 1.3 to
> 1.4.
>
> > 2. We need to configure only OFPTFF_FIRST_EGRESS flag and all the table
> > before this will be considered as ingress tables and all the table after
> > the first egress table will be considered as egress tables.
>
>         That's what I would do.
>
> > Thanks and Regards
> > Niti Rohilla
>
>         Good luck !
>
>         Jean
>



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