Re: [PATCH] src: proto: support DF, LE, VA for DSCP

[Pablo Neira Ayuso <pablo@netfilter.org>]

On Tue, Jun 28, 2022 at 08:29:42PM +0200, Oleksandr Natalenko wrote:
> Hello.
> 
> Thank you for your response. Please find my comments inline.
> 
> On pondělí 27. června 2022 19:31:27 CEST Pablo Neira Ayuso wrote:
> > On Mon, Jun 20, 2022 at 08:58:07PM +0200, Oleksandr Natalenko wrote:
> > > Add a couple of aliases for well-known DSCP values.
> > > 
> > > As per RFC 4594, add "df" as an alias of "cs0" with 0x00 value.
> > > 
> > > As per RFC 5865, add "va" for VOICE-ADMIT with 0x2c value.
> > 
> > Quickly browsing, I don't find "va" nor 0x2c in this RFC above? Could
> > you refer to page?
> 
> As per my understanding it's page 11 ("2.3.  Recommendations on implementation of an Admitted Telephony Service Class") here:
> 
>       Name         Space    Reference
>       ---------    -------  ---------
>       VOICE-ADMIT  101100   [RFC5865]
> 
> Am I wrong?

Ok, hence the 'va'.

> > > As per RFC 8622, add "le" for Lower-Effort with 0x01 value.
> > 
> > This RFC refers to replacing CS1 by LE
> > 
> >    o  This update to RFC 4594 removes the following entry from its
> >       Figure 4:
> > 
> >    |---------------+------+-------------------+---------+--------+----|
> >    | Low-Priority  | CS1  | Not applicable    | RFC3662 |  Rate  | Yes|
> >    |     Data      |      |                   |         |        |    |
> >     ------------------------------------------------------------------
> > 
> >       and replaces it with the following entry:
> > 
> >    |---------------+------+-------------------+----------+--------+----|
> >    | Low-Priority  | LE   | Not applicable    | RFC 8622 |  Rate  | Yes|
> >    |     Data      |      |                   |          |        |    |
> >     -------------------------------------------------------------------
> > 
> > 
> > static const struct symbol_table dscp_type_tbl = {
> >         .base           = BASE_HEXADECIMAL,
> >         .symbols        = {
> >                 [...]
> >                 SYMBOL("cs1",   0x08),
> >                 [...]
> >                 SYMBOL("le",    0x01),
> 
> I think we shouldn't remove existing symbol, should we? Please let
> me know if I missed any suggested action item for myself here.

Not removing. I mean, if I understood correctly, the RFC says LE == cs1 ?
But the values are different.

> > > tc-cake(8) in diffserv8 mode would benefit from having "le" alias since
> > > it corresponds to "Tin 0".
> > 
> > Aliasing is fine, let's just clarify this first.
> 
> I mean, "le" would be an alias to "0x01", not to "cs1".
> 
> BTW, the reason I included Loganaden Velvindron in Cc is that "le"
> was already added in the past, but got quickly reverted as it broke
> some tests. Shall "le" interfere with "less-equal", or what could be
> the issue with it? If the name is not acceptable, "lephb" or similar
> can be used instead.

Oh right, this is an issue for the parser, the 'le' keyword is an
alias of '<='.

What does 'lephb' stands for BTW?

Note that these aliases will be lost when listing back the ruleset
from the kernel, so it is only working as an input.