[Roll] draft-ietf-roll-routing-metrics-03.txt

[Adrian Farrel <Adrian.Farrel at huawei.com>]

Hi,

Thanks for presenting today.

Something jumped out.

In the common header you have...

   0                   1                   2                   3
   0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |Routing-Ob-Type|Res|R|G| A |O|C|   Object Length (bytes)       |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
  |                                                               |
  //                        (Object body)                        //
  |                                                               |
  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Figure 2: Routing Metric/Constraint common header format

Are you worried that you have only two more unused bits? Is there a risk 
that you will run out very soon?

On the other hand, do you really need 16 bits for the length in bytes of the 
object? Are you tied to this format by the RPL spec, or could you create 
yourself 8 more flag bits by reducing the Object Length to 8 bits?

Cheers,
Adrian