Hello Amanda;
The current draft has this:
+-------------+------+-------------------------------------------+
| Bit Pattern | Page | Header Type |
+-------------+------+-------------------------------------------+
| 00 000000 | TBD1 | Uncompressed NDN Interest messages |
| 00 100000 | TBD1 | Uncompressed NDN Data messages |
| 01 000000 | TBD1 | Uncompressed CCNx Interest messages |
| 01 100000 | TBD1 | Uncompressed CCNx Content Object messages |
| 10 0xxxxx | TBD1 | Compressed NDN Interest messages |
| 10 1xxxxx | TBD1 | Compressed NDN Data messages |
| 11 0xxxxx | TBD1 | Compressed CCNx Interest messages |
| 11 1xxxxx | TBD1 | Compressed CCNx Content Object messages |
+-------------+------+-------------------------------------------+
The Uncompressed form has the 4 rightmost bits set to 0 while the compressed
has them xxxxx.
Which leaves lots of unassigned space un the Uncompressed range.
This simple proposal seems to break the symmetry of compressed forms.
| 10 0xxxxx | TBD1 | Compressed NDN Interest messages |
| 10 1xxxxx | TBD1 | Compressed NDN Data messages |
| 10 0xxxxx | TBD1 | Compressed CCNx Interest messages |
| 11 10xxxx | TBD1 | Compressed CCNx Content Object messages |
Maybe 4 bits is sufficient in all compressed forms? If so we can do better:
+-------------+------+-------------------------------------------+
| Bit Pattern | Page | Header Type |
+-------------+------+-------------------------------------------+
| 00 000000 | TBD1 | Uncompressed NDN Interest messages |
| 00 000001 | | |
| ... | | Unassigned |
| 00 001111 | | |
| 00 01xxxx | TBD1 | Compressed NDN Interest messages |
| 00 100000 | TBD1 | Uncompressed NDN Data messages |
| 00 100001 | | |
| ... | | Unassigned |
| 00 101111 | | |
| 00 11xxxx | TBD1 | Compressed NDN Data messages |
| 01 000000 | TBD1 | Uncompressed CCNx Interest messages |
| 01 000001 | | |
| ... | | Unassigned |
| 01 001111 | | |
| 01 01xxxx | TBD1 | Compressed CCNx Interest messages |
| 01 100000 | TBD1 | Uncompressed CCNx Content Object messages |
| 01 100001 | | |
| ... | | Unassigned |
| 01 101111 | | |
| 01 11xxxx | TBD1 | Compressed CCNx Content Object messages |
+-------------+------+-------------------------------------------+
Works?
Pascal
This leaves unassigned space
> -----Original Message-----
> From: Amanda Baber via RT <[email protected]>
> Sent: mercredi 22 septembre 2021 19:30
> Cc: Eric Vyncke (evyncke) <[email protected]>; [email protected];
> [email protected]; [email protected]; Pascal Thubert
> (pthubert) <[email protected]>; [email protected]; [email protected]
> Subject: [IANA #1200929] expert review for draft-irtf-icnrg-icnlowpan-10
>
> Hi,
>
> IANA has been asked to notify the 6lo group and the authors of RFC 8025 as
> well as the IESG-designated experts that the authors of draft-irtf-icnrg-
> icnlowpan-10 (and the RG) have accepted a proposed change to an assignment
> in that document.
>
> Carles and Shwetha, can you confirm that we can move forward with this
> registry update?
>
> The issue is that Table 2 in https://datatracker.ietf.org/doc/html/draft-
> irtf-icnrg-icnlowpan is currently instructing IANA to make this
> registration in the Dispatch Type Field registry (we understand that this
> "TBD1" should be page 14):
>
> 11 1xxxxx | TBD1 | Compressed CCNx Content Object messages
>
> However, 11 11xxxx has already been assigned to "Page switch" for pages 0-
> 15:
>
> https://www.iana.org/assignments/_6lowpan-parameters
>
> This is the solution suggested by the experts and accepted by the authors:
>
> =====
>
> One simple solution could be as follows:
>
> OLD:
> 11 1xxxxx | TBD1 | Compressed CCNx Content Object messages
>
> NEW:
> 11 10xxxx | TBD1 | Compressed CCNx Content Object messages
>
> A drawback of this solution is that it reduces the space of this type of
> messages (from 32 options to 16 options, for this specific type of
> messages), but perhaps it could be sufficient.
>
> =====
>
> The authors write, "The simple solution provided by the designated experts
> is sufficient. The drawback does not affect the option space, since that
> particular dispatch also contains a 'Reserved' bit. We can trade this for
> the longer prefix '11 10xxxx' (instead of '11 1xxxxx')."
>
> Best regards,
>
> Amanda Baber
> IANA Operations Manager
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