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From: Carsten Bormann <cabo@tzi.org>
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 <CABCOCHQxeV19j=5XHJz4UV3_nLbRHJ904d8GWyxQNdA9e2W_QA@mail.gmail.com>
Date: Sat, 22 Feb 2025 18:36:30 +0100
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 <CABCOCHQxeV19j=5XHJz4UV3_nLbRHJ904d8GWyxQNdA9e2W_QA@mail.gmail.com>
To: Andy Bierman <andy@yumaworks.com>
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CC: Michael Richardson <mcr+ietf@sandelman.ca>, core <core@ietf.org>,
 CBOR <cbor@ietf.org>, netconf@ietf.org
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Subject: =?utf-8?q?=5Bnetconf=5D_Re=3A_=5Bcore=5D_adding_PEN-based_SID_allocation_to_?=
	=?utf-8?q?RFC9595?=
Archived-At: 
 <https://mailarchive.ietf.org/arch/msg/netconf/ylvphqI9fcqe7_3MBkhuMfPn5Qw>

Hi Andy,

Apologies for Apple mail not picking up the difference between what you =
wrote and what MCR wrote.
So, one of you said :-):

> Carsten started a thread about PEN-based range assignments (not sure =
where)

I wrote a draft a while ago:

https://www.ietf.org/archive/id/draft-bormann-core-yang-sid-pen-01.html

These are numbers in the 64-bit space.
If you want to get 32-bit numbers for better deltas, we have to be a bit =
more frugal.
(We could still do both a chunk of 32-bit numbers and a wider swatch of =
64-bit numbers at the same time.)

(Let=E2=80=99s say we want to accommodate up to 19 bit PENs, and we want =
to allocate 31 of the 32 bits of 1+4 space, leaving the rest for =
mega-ranges, we=E2=80=99d have 4096 SIDs for each PEN.
Organizations that need more can just get a mega-range.)ef

> - A mini-range could be automatically assigned for PEN
>     20 bits: PEN   + 12 bit SID range  =3D=3D 4096 SIDs per PEN

Yes, but we still need space for mega ranges.

> - A real mega-range must be allocated if 4096 SIDs are not enough or =
2^^20 PENs gets filled up

If there are 2**20 PENs, we=E2=80=99ll have to rethink this.
2**19 is 8 times what we have allocated so far.

> Another alternative is to create a vendor-proprietary FCFS range under =
the
> IETF Mega-Range.   I think that 100K numbers would be plenty for now.
> Or we could create another Mega-Range for this.

We don=E2=80=99t need to do this, because:

> I am thinking about starting an OpenSID (public) mega-range and just =
creating SID files
> for every publicly available YANG module.  netconfcentral.org already =
tracks over 4000 modules.
> IMO the rule that there SHOULD only be one SID assignment for each =
YANG schema node
> is not required and impeding any progress to YANG/CBOR adoption.

That=E2=80=99s what 9254 says: It=E2=80=99s not required, but still =
rather useful.

> One issue that came up was that IANA does not want to manage all the =
mega-ranges.

What do you mean by that?
Manage the mega-ranges (per se) or manage the SIDs inside each =
mega-range?
The point is that the owner of the mega-range does the latter.

> This requires excellent tooling and procedures, neither of which are =
mature yet.
> An automatic PEN range would not need any IANA involvement.

Correct.

> IMO waiting for each "owner" of the YANG module to publish a SID file =
is a non-starter.
> There are no SID files yet and adding them 1 or 2 at a time will take =
a decade.

I like you idea of going ahead and publishing SID files for random =
vendor stuff where the vendor is not doing its homework.
But if they do, they should be in control.

> I've asked for time to present about
> draft-richardson-netmod-atrest-extensions, which is very much a =
drafty-draft.

The main useful idea I see here is submaps. =20
That allows the deltas to be more efficient if you augment a module with =
more than one item.

> In order to let private enterprises do their own extensions, having =
SIDs
> would help. =20

We could also cbor-packed=E2=80=94like table setups for data-item =
internal SID ranges.
Requires more thinking.
Lots of complexity without a clear benefit, though.

> Without SIDs for every module in use the YANG/CBOR encoding is not =
really worth using.
> Any effort to get some SID files out there would help.

Yes!  Let=E2=80=99s

* Fix PYANG to spit out conforming output (or use my tools for making =
the PYANG output conforming)
* Go ahead with the YANG-SID Modules Designated Experts (Michel =
Veillette, Alexander Pelov, Laurent Toutain) and register everything =
that belongs to the IETF
* Do the IEEE thing
* Set up something that enables third-party registrations of SIDs for =
other YANG modules

Now, doing the PEN thing (32, 64, or both) is kind of orthogonal to =
that; I can update my draft to provide a 32-bit range (say, 4000 SIDs =
per PEN) as well in addition to the 64-bit range already in the draft =
(100000 SIDs per PEN).

Gr=C3=BC=C3=9Fe, Carsten